ASTARTE · Abstract (for dissemination) This deliverable provides a summary of selected submarine networks in connection with Tsunami Early Warning Systems while providing a de facto

ASTARTE [603839] – Deliverable 6.6

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ASTARTE

Assessment, STrategy And Risk Reduction for Tsunamis in Europe

Grant Agreement no: 603839

Organisation name of lead contractor: IPMA

Coordinator: Maria Ana Baptista

Deliverable 6.6

Report on the integration of the submarine sensor data

Due date of deliverable: M12

Actual submission date to PC: M12

Start date of the project: 01/11/2013

Duration: 36 months

Work Package: WP6 “Operational detection and communication infrastructure”

Lead beneficiary of this deliverable: KOERI

Author(s): Ocal Necmioglu, Mustafa Comoglu, Mehmet Yılmazer, Dogan Kalafat

Version: v1.5

Project co-funded by the European Commission within the Seventh Framework Programme (2007-2013)

Dissemination Level1

PU Public

PP Restricted to other programme participants (including the Commission Services)

RE Restricted to a group specified by the consortium (including the Commission Services)

CO Confidential, only for members of the consortium (including the Commission Services)

1 Please mark with X the dissemination level of the deliverable (check DoW if any questions arise)


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TABLE OF CONTENTS

Table of Contents

EXECUTIVE SUMMARY ................................................................................................................... 3

DOCUMENT INFORMATION ......................................................................................................... 4

LIST OF TABLES ................................................................................................................................ 7

ABBREVIATIONS AND ACRONYMS ............................................................................................ 8

CHAPTER 1: THE NEED FOR A SUBMARINE SENSOR NETWORK FOR THE TSUNAMI

WARNING SYSTEMS ........................................................................................................................ 9

CHAPTER 2: EXAMPLES OF SUBMARINE SENSOR NETWORKS ...................................... 11

2.1 DONET ............................................................................................................................................. 11

2.1.1 System Concepts ...................................................................................................................... 11

2.1.2 Backbone Cable System ........................................................................................................... 12

2.1.3 Science Node ........................................................................................................................... 13

2.1.4 DONET in Operation ................................................................................................................. 14

2.1.5 DONET2 .................................................................................................................................... 15

2.2 DART® (Deep-ocean Assessment and Reporting of Tsunamis)....................................................... 16

2.2.1 DART II System Components and Characteristics .................................................................... 18

2.2.2 Pressure Sensor ........................................................................................................................ 20

2.2.3 Reciprocal Counter ................................................................................................................... 20

2.2.4 Computer ................................................................................................................................. 20

2.2.5 Acoustic Modem and Transducer............................................................................................. 20

2.2.6 Tilt Sensor ................................................................................................................................. 21

2.2.7 Batteries ................................................................................................................................... 21

2.2.8 Tsunami Detection Algorithm .................................................................................................. 21

2.2.9 Reporting Modes .................................................................................................................. 21

2.2.10 Surface Buoy .......................................................................................................................... 22

2.3 MARMARA SEA OBO ....................................................................................................................... 22

2.3.1 Detecting Small Earthquakes with OBS.................................................................................... 31

2.4 Neutrino Mediterranean Observatory Submarine Network 1 ....................................................... 34

2.4 POSEIDON PYLOS ............................................................................................................................ 35

2.5 TSUNAMI EARLY WARNING SYSTEM IN ROMANIA-BULGARIA ....................................................... 37

CHAPTER 3: CASE STUDY – POSSIBLE LOCATIONS FOR THE IMPLEMENTATION OF

A DONET-LIKE SYSTEM IN TURKEY ........................................................................................ 40

CHAPTER 4: CONCLUSIONS ........................................................................................................ 42

REFERENCES .................................................................................................................................... 43


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EXECUTIVE SUMMARY

This deliverable provides a summary of selected submarine networks in connection with Tsunami

Early Warning Systems while providing a de facto comparison between what is currently available in

the Euro-Mediterranean Region and around the globe. Several systems, such as DONET (JMA), DART

(NOAA), Marmara OBO (KOERI), Poseidon Pylos (HCMR-NOA), and Neutrino (Italy) have been

discussed. Special emphasis is given to Marmara OBO due to the fact that the system is operated by

KOERI. A DONET type system is found to be most beneficial to the TWS in the Euro-Mediterranean

(NEAM) region as the ability to record both earthquake and tsunami signals at the same observation

points should be considered. This is a necessity of the fact that the tsunami sources are located in a

very near distance to the coast, especially in the Mediterranean basin. To address this, this

deliverable proposes several locations around Turkey for the possible deployment of submarine

sensor networks. Internally, this deliverable is expected to provide input to “D6.31 Definition of

optimum sensor locations”. Externally, this deliverable is expected to provide input to WP7,

specifically to “D7.28 Tsunami forecast capabilities in the NEAM region (M27)”.


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DOCUMENT INFORMATION

Project

Number

FP7 - 603839 Acronym ASTARTE

Full Title Assessment, STrategy And Risk Reduction forTsunamis in Europe

Project URL http://www.astarte-project.eu/

Document URL

EU Project Officer Denis Peter

Deliverable Number D6.6 Title Report on the integration of the submarine sensor data

Work Package Number WP6 Title Operational

detection and

communication

infrastructure

Date of Delivery Contractual M12 Actual M12

Status version 1.3 final □

Nature prototype □ report ☑ dissemination □

Dissemination level public □ consortium □

Authors (Partner) Ocal Necmioglu (KOERI), Mustafa Comoglu (KOERI), Mehmet Yılmazer (KOERI),

Dogan Kalafat (KOERI)

Responsible Author Name Ocal Necmioglu E-mail [email protected]

Partner KOERI Phone +905326385419

Abstract

(for dissemination)

This deliverable provides a summary of selected submarine networks in

connection with Tsunami Early Warning Systems while providing a de

facto comparison between what is currently available in the Euro-

Mediterranean Region and around the globe. Several systems, such as

DONET (JMA), DART (NOAA), Marmara OBO (KOERI), Poseidon Pylos

(HCMR-NOA), and Neutrino (Italy) have been discussed. Special emphasis

is given to Marmara OBO due to the fact that the system is operated by

KOERI. A DONET type system is found to be most beneficial to the TWS in

the Euro-Mediterranean region as the ability to record both earthquake

and tsunami signals at the same observation points should be considered.

This is a necessity of the fact that the tsunami sources are located in a

very near distance to the coast, especially in the Mediterranean basin. To

address this, this deliverable proposes several locations around Turkey for

the possible deployment of submarine sensor networks

Keywords Tsunami Early Warning, Submarine Sensor

Version Log

http://www.astarte-project.eu/


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Issue Date Rev. No. Author Change

18.10.2014 1.2 Ocal Necmioglu Updated Figure 37

19.10.2014 1.3 Ocal Necmioglu Removed Table 4

27.10.2014 1.4 Ocal Necmioglu Updated the deliverable

according to the list of comments

provided by the Coordinator

29.10.2014 1.5 Ocal Necmioglu Added NIEP contribution


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LIST OF FIGURES Figure 1: ICG/NEAMTWS Decision Matrix for the Mediterranean and its Connected Seas (source:

NEAMTWS-IOUG) ............................................................................................................................ 9 Figure 2: ICG/NEAMTWS definition of ranges (source: NEAMTWS-IOUG) ........................................... 10 Figure 3: ICG/NEAMTWS Decision Support Matrix (source: NEAMTWS-IOUG) ................................... 10 Figure 4: The concept of submarine cabled real-time seafloor observatory network (source: DONET -

Copyright 2008 Japan Agency for Marine-Earth Science and Technology) .................................. 11 Figure 5: System Concept of DONET (source: DONET - Copyright 2008 Japan Agency for Marine-Earth

Science and Technology) ............................................................................................................... 12 Figure 6: The power distribution control system (source: DONET - Copyright 2008 Japan Agency for

Marine-Earth Science and Technology) ........................................................................................ 13 Figure 7: Operational DONET (source: DONET - Copyright 2008 Japan Agency for Marine-Earth

Science and Technology) ............................................................................................................... 14 Figure 8: 2011 Tohoku earthquake tsunami signals recorded by DONET (source: DONET - Copyright

2008 Japan Agency for Marine-Earth Science and Technology) ................................................... 15 Figure 9: Hypocenters of earthquakes around the Nankai through determined by the DONET (source:

DONET - Copyright 2008 Japan Agency for Marine-Earth Science and Technology) ................... 15 Figure 10: DONET and DONET2 (source: DONET - Copyright 2008 Japan Agency for Marine-Earth

Science and Technology) ............................................................................................................... 16 Figure 11: Locations of DART systems (source: NOAA) ........................................................................ 17 Figure 12: Context diagram showing a DART II system and the related telecommunication nodes

(source: NOAA) ............................................................................................................................. 18 Figure 13: Tsunameter block diagram showing how the components interact (source: NOAA) ......... 19 Figure 14: Block diagram of DART II surface buoy (source: NOAA) ...................................................... 22 Figure 15: Elements and the architectural configuration of the SBO system in Marmara (source:

KOERI) ........................................................................................................................................... 23 Figure 16: Scenes from the deployment of the SBO system in Marmara Sea (source: KOERI) ............ 23 Figure 17: Sea-bottom observation system in Marmara Sea (source: KOERI) ..................................... 24 Figure 18: An example of a local event recorded by the SBO but not by any land-based stations

(source: KOERI) ............................................................................................................................. 25 Figure 19: A typical large local event both recorded by strong motion and the broadband sensors

(source: KOERI) ............................................................................................................................. 26 Figure 20: The combined amplitude dynamic range of both the broadband and the strong motions

stations is more than 200 dB (source: KOERI) .............................................................................. 26 Figure 21: GSL OBO sensor system being installed with an ROV (source: GURALP) ............................ 28 Figure 22: Inside of the sensor system (source: GURALP) .................................................................... 28 Figure 23: The Neptune OBO sensor being installed with ROV, buried for good coupling and long-

term stability (source: GURALP) ................................................................................................... 29 Figure 24: Neptune OBO sensors being tested prior to delivery at GSL vault (source: GURALP) ........ 29 Figure 25: sensor system that can be used with ROV installation or as part of concrete domed OBO

station (source: GURALP) ............................................................................................................. 30 Figure 26: Covering an OBO sensor with a dome without burying is an effective way to install a

broad-band sensors system (source: GURALP) ............................................................................. 30 Figure 27: Releasing the station package with the cabling and the concrete dome (source: GURALP)

...................................................................................................................................................... 30 Figure 28: Thirty seconds of data shown (source: GURALP) ................................................................. 31 Figure 29: Ten seconds of data shown (source: GURALP) .................................................................... 32 Figure 30: Twenty seconds of data shown (source: GURALP) .............................................................. 32 Figure 31: Twenty seconds of data shown (source: GURALP) .............................................................. 33 Figure 32: Three seconds of data shown (source: GURALP) ................................................................. 33 Figure 33: Five seconds of data shown (source: GURALP) .................................................................... 34


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Figure 34: Location of Neutrino Mediterranean Observatory Submarine Network 1 ......................... 35 Figure 35: Location of the POSEIDON-Pylos site (left) and deployment of the seabed platform at the

POSEIDON-Pylos site in November 2008 (source: HCMR) ............................................................ 36 Figure 36: Further figures from POSEIDON-Pylos site deployment (source: HCMR) ........................... 37 Figure 37: Buoys and Tsunami Modules installation sites .................................................................... 38 Figure 38: Surface Relay Buoy (SRB) scheme ........................................................................................ 39 Figure 39: Selected locations for the possible establishment of a DONET-like system in Turkey are

shown on the map: İğneada NPP and Sinop NPP in Black Sea, Marmara (M) Region, Akkuyu NPP in ................................................................................................................................................... 40

Figure 40: Outline of the proposed DONET-like MARMARA Observation Network ............................. 41

LIST OF TABLES Table 1: DART II performance characteristics (source: NOAA) ............................................................. 19 Table 2: Details of the Marmara SBO Sites (source: KOERI) ................................................................. 25 Table 3: Phase parameters related to the recordings at OBO-4 and OBO-3 sites for the 6 Feb 11 at

13:05:19 UTC microearthquake occurred in the Southwestern part of the Sea of Marmara (source: GURALP) .......................................................................................................................... 31

Table 4: Buoys and Tsunami Modules installation positions ................................................................ 38 Table 5: Subsurface Instrumented Package Specifications ................................................................... 39 Table 6: Cable lengths of the proposed DONET-like MARMARA Observation Network ...................... 41


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ABBREVIATIONS AND ACRONYMS

DART® Deep-ocean Assessment and Reporting of Tsunamis DM Decision Matrix

DONET Dense Oceanfloor Network System for Earthquakes and Tsunamis

EEW Earthquake Early Warning

GeoEcoMar National Institute for Marine Geology and Geoecology (Romania)

GURALP Guralp Systems Ltd.

ITU-T The Study Groups of International Telecommunication Union (ITU)

Telecommunication Standardization Sector

KOERI Kandilli Observatory and Earthquake Research Institute (Turkey)

NIEP The National Institute for Earth Physics (Romania)

NOAA National Oceanic and Atmospheric Administration (USA)

NEAMTWS Tsunami Early Warning and Mitigation System in the North-eastern Atlantic, the

Mediterranean and connected seas

NEMO-SN1 Neutrino Mediterranean Observatory - Submarine Network 1 seafloor observatory

NPP Nuclear Power Plant

OBO Ocean Bottom Observatory

TFP Tsunami Forecast Point


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CHAPTER 1: THE NEED FOR A SUBMARINE SENSOR NETWORK FOR THE

TSUNAMI WARNING SYSTEMS

Most earthquakes are located at plate boundaries and approximately 85 % of the total

seismic moment is released during large subduction earthquakes at active margins. Ocean bottom

seismometers exist since the 1930’s (Charvis et al., 2009). Existing Earthquake Early Warning

Systems (EEW) continually process real-time seismic data to determine when a potentially damaging

earthquake is underway by utilising the first arriving, low-amplitude P-waves to predict the

impending arrival of the higher energy later arriving (e.g. Allen and Kanamori, 2003). The most

advanced algorithms can differentiate between a relatively minor Mw 6 and a catastrophic Mw 7-9

earthquake using only the first few seconds’ worth of data. In addition, seafloor real-time seismic

data would greatly improve our ability to differentiate between earthquakes that generate

damaging tsunamis and earthquakes that do not generate tsunami.

Given the short distance of the tsunamigenic sources to the coast in the NEAM Region,

especially in the Mediterranean and its Connected Seas, the seismic waveforms start to be collected

by the NTWC only a few seconds after the onset of the earthquake. The duty personnel will respond

immediately and begin their analysis of the event. It is desirable that a first evaluation of the

earthquake parameters is computed in less than 5 minutes after its origin time. The earthquake

analysis includes automatic and interactive processes for determining the earthquake's epicentre,

depth, and origin time, as well as its moment magnitude. These fundamental limitations dictate

three options of operations in NEAMTWS:

A. Use of ICG/NEAMTWS Decision Matrix (DM)

In this case, the parameters defined in the ICG/NEAMTWS DM are the key elements to

produce the alert message. The system measures the distance between the epicenter and the

Tsunami Forecast Points (TFP-These are the forecast points submitted to the NEAMTWS and nothing

else and they should be independent of the Scenario Database) and produces the alert message.

Alert levels are defined by the ICG/NEAMTWS Decision Support Matrix (DSM).

Figure 1: ICG/NEAMTWS Decision Matrix for the Mediterranean and its Connected Seas (source:

NEAMTWS-IOUG)


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Figure 2: ICG/NEAMTWS definition of ranges (source: NEAMTWS-IOUG)

Figure 3: ICG/NEAMTWS Decision Support Matrix (source: NEAMTWS-IOUG)

Messages are produced basin specific. If the event is in the Aegean, no TFPs in Black Sea are

considered and vice versa. In short, Black Sea and Eastern Mediterranean/Aegean Sea are two

distinct basins from the operational point of view. Assuming that the tsunami signal at the sea-level

stations has been observed, the messages would be updated only when wave heights corresponding

to different alert levels has been observed.

B. Use Scenario Database (SDB)

The use of a tsunami Scenario Database is considered as the best methodology, subject to

the availability of high-resolution bathymetry and topography data used in the tsunami modelling.

Moreover, due to specific local conditions, the varaiation of tsunami wave heights at nearby TFPs

may vary drastically and correspond to different alert levels. This could constitute a problem

concerning the effective use of the warning messages by the end-user, namely Disaster and

Emergency Management Offices and/or Civil Protection Authorities.

C. Joint Utilization of the Decision Matrix and Scenario Database

Such a joint methodology could use the Decision Matrix to trigger the first tsunami analysis.

Once the warning message has been disseminated, the evaluation of the event could be monitored

and observed signals could be analyzed and evaluated with respect to the Tsunami Scenario

Database.

Normally, the first estimates of Mw have to be derived from a small length of the seismic

waveforms and the issuance of the tsunami warning message will be based on a Decision Matrix as

agreed by the ICG/NEAMTWS. The earthquake evaluation will continue after the first message is

issued, integrating more data and allowing more extensive analysis. If there were significant changes

to the initial parameters, then the NTWC would decide to issue a supplement message.


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As it could be seen above, the system is heavily dependent on the first estimates of Mw and

the verification of the tsunami could be only made after the tsunami arrives the TFP in the absence

of offshore sea-level observational network. Therefore, it’s especially important to be as close as

possible to the possible tsunami generating earthquake source. Such a requirements could only be

fulfilled by the use of a real-time cabled observational network, such as DONET, to be integrated in

to the 24/7 operational National Earthquake Monitoring Centers within the NEAMTWS.

CHAPTER 2: EXAMPLES OF SUBMARINE SENSOR NETWORKS

2.1 DONET

2.1.1 System Concepts

The DONET is a submarine cabled real-time seafloor observatory network for the precise

earthquake and tsunami monitoring in Japan. For the purpose of understanding and forecasting the

earthquake and related activities underneath the seafloor, the twenty sets of state-of-arts

submarine cabled sub-sea measurement instrument are being deployed in seafloor at the interval of

15-20km. The twenty sets of preliminary interface are prepared in consideration of the improvement

of observation capability in the future. Operating large-scale subsea infrastructure over a long period

of time (20-30 years) is one of a challenge of underwater technology. The increase of measurement

instruments has a big influence on the total system reliability; because of the state-of-arts

instrument is a bottleneck to maintain long-term reliability. A novel system design concept is

necessary for the observatory network development to make two demands such as 'high reliability

system design' and 'state-of-arts measurement' united. The observatory network should be able to

replace, maintenance and extend while operating, and should be have a redundancy for the internal

or external observatory network component failure. To achieve these requirements, the DONET

proposes a composition that consists of three major components with different system reliability.

There are high reliability backbone cable system, replaceable science node, and extendable

measurement instruments.

Figure 4: The concept of submarine cabled real-time seafloor observatory network (source: DONET - Copyright 2008 Japan Agency for Marine-Earth Science and Technology)


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Figure 5: System Concept of DONET (source: DONET - Copyright 2008 Japan Agency for Marine-Earth Science and Technology)

2.1.2 Backbone Cable System

The backbone cable system provides the power feed line and the communications channel to the

apparatus in the seafloor. The system brings a recently developed sub-sea telecommunication cable

technologies to fit for the high reliability requirement for 20 years seamless observation. A constant

current DC power supply technology provides high robustness against with unexpected power line

failures. The DONET backbone cable system allows loading up to 3kW (3kVDC / 1A) electric power in

operation. The five science node interfaces are scheduled to be equipped in the system. A

duplicated pier-to-pier optical fiber physical communications channel is allocated between science

node interfaces and terminal equipments on land to ensure the reliability. The optical amplifiers

(repeaters) are prepared every 40-60km optical fiber length interval to transmit the signal longer

distance without degradation. These repeaters correspond to the coherent optical time-domain

reflectometry (C-OTDR) optical fiber fault detection system. The branching unit (BU) is an interface

for science node interface. This unit controls the high voltage power feed path in backbone cable

system, and has a function to separate a science node when the node interface one by one

becoming unexpected status. For the connection between a BU and a science node interface, a

dual conductor light weight submarine cable that met ITU-T recommendations is being

developed in this project.


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2.1.3 Science Node

The science node is a device with the role of hub that connects the backbone cable system

to sub-sea instruments. Many of novel technologies are consolidated in the science node

development. A hybrid (fiber optic and electric) interface make possible to put on and take off the

science node from backbone cable system. Eight hybrid connectors per a science node have been

reserved for measurement instruments. The power distribution control, data transmission control,

and precise timing control function in the science node are most critical components of DONET

development. The power distribution control system receives 500watts of constant current DC

power supplied from the terminal equipment, and distributes 45 watts of secondary power output

to a measurement instrument as the occasion demands. The secondary power output features a

constant current DC power output system to ensure the reliability of sub-sea system and efficiency

of power transmission to measurement equipment. The power distribution control system has a

mechanism to balance the power consumption of science node constant to prevent the system from

unstable power distribution status. This function is essential for monitoring the condition of entire

observatory network.

The data transmission control system handle data link and precise timing / clock control

between measurement instrument and terminal equipment. The STM (Synchronous Transfer Mode)

on SONET / SDH (Synchronous Digital Hierarchy) is selected to realize the precise time

synchronization requirement. The data link between terminal equipment and science node is

running at approximately 600Mbit/s. The bidirectional data transmission between measurement

instrument and science node, is running at 50Mbit/s. precise time synchronization is a key function

of science use of submarine cable system. The synchronous transmission system makes possible the

high accurate time synchronization between GPS clock on terminal equipment and measurement

instrument in seafloor. The timing circuit develops aiming at the accuracy of time synchronization of

less than 1microsecond in this project.

Figure 6: The power distribution control system (source: DONET - Copyright 2008 Japan Agency for Marine-Earth Science and Technology)


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2.1.4 DONET in Operation

DONET is a submarine cabled real-time seafloor observation infrastructure designed to

realize precise earthquakes and tsunamis monitoring on seafloor in the long period of time. The

density of observatories is comparable to the earthquake observatory network on land and the

tsunami monitoring is an unprecedented capability. The main purpose of DONET is to monitor the

hypocentral region of Tonankai earthquake that is predicted to occur with a probability of more than

70% within the next 30 years according to the report published by the Earthquake Research

Committee. DONET consists of an approximately 300km length of backbone cable system, 5 science

nodes, and 20 observatories. Its installation on 20 stations at Kumanonada started in 2006 and has

been completed in July 2011. In August 2011, the seismic data has started to be provided to the

Japan Meteorological Agency and the National Research Institute for Earth Science and Disaster

Prevention, where the data will be used for the earthquake early warning.

Figure 7: Operational DONET (source: DONET - Copyright 2008 Japan Agency for Marine-Earth Science and Technology)

DONET recorded distinct tsunami signals of the 2011 Tohoku earthquake with pressure

gauges. The maximum amplitude at the stations is about 0.2-0.3 m in the period band between 100

to 10000 sec. These signals were found 15 min before the arrivals at the nearest site, Owase city,

Mie prefecture. This shows that the offshore DONET data are very useful to quickly estimate water

heights in near shore areas for disaster mitigation. The pressure gauge data are also useful for

analyzing micro-tsunami, geodetic deformation, tide, water temperature, and related ocean

phenomena.


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Figure 8: 2011 Tohoku earthquake tsunami signals recorded by DONET (source: DONET - Copyright

2008 Japan Agency for Marine-Earth Science and Technology)

In addition, the hypocenters of earthquakes that occurred around the Nankai trough have

been determined by using the data obtained from DONET. Intensive seismic activity off the Kii

Peninsula was found. The earthquakes are mainly distributed in three clusters, of which locations

well overlap with the aftershock distribution of the 2004 off the Kii Peninsula earthquakes

(M_JMA=6.9 and 7.4). Thus, it is considered that most earthquakes in the present activity are

aftershocks of the 2004 earthquakes.

Figure 9: Hypocenters of earthquakes around the Nankai through determined by the DONET (source:

DONET - Copyright 2008 Japan Agency for Marine-Earth Science and Technology)

2.1.5 DONET2


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In parallel with DONET construction, DONET2 (the second phase of DONET) has started since

2010 to monitor a wider region; the monitoring area expands to the west side of DONET. It will be a

larger scale compared to DONET and observatory equipment is scheduled to be installed on 29

stations at offshore Kii peninsula. DONET2 will consist of a 450km length backbone cable system

with 2 landing stations, 7 science nodes, and 29 observatories (the landing locations remain to be

determined). The subsea construction has started at the beginning of 2013 for starting operation in

2015. Additionally, two more observatories will be added to DONET.

Figure 10: DONET and DONET2 (source: DONET - Copyright 2008 Japan Agency for Marine-Earth Science and Technology)

2.2 DART® (Deep-ocean Assessment and Reporting of Tsunamis)

DART® systems are developed by NOAA’’s Pacific Marine Environmental Laboratory

(PMEL). The information collected by a network of DART® systems positioned at strategic locations

throughout the ocean plays a critical role in tsunami forecasting.

The history of the development of real-time measurements of tsunamis in the deep ocean

for the purpose of forecasting coastal tsunami impacts will be presented, with early history to

include the various instruments tested to determine if tsunamis could be measured in the deep

ocean. The measurement of pressure changes induced by the tsunami required a high resolution

pressure sensor installed on the seafloor, to provide a motionless environment that allowed the

ocean to filter out higher frequency ocean waves. Instruments included bourdon tubes and vibrating

crystals that rested on the seafloor and used the depth of the ocean as a pressure reference. Once

deep ocean measurements were deemed possible, testing and evaluation was used to identify which

technology was accurate, affordable, and reliable enough to be used for tsunami forecasting under


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tsunami warning conditions. National Oceanic and Atmospheric Administration (NOAA) had

completed the research and development, including an operational prototype, by October of 2003,

when the technology was transferred to NOAA operations. The first generation Deep-ocean

Assessment and Reporting of Tsunamis (DART I) array consisted of six stations strategically located

off Alaska, Oregon, and near the equator to detect tsunamis originating in the Chile/Peru area. The

original DART array demonstrated its value within four months by measuring a small tsunami

originating in Alaska and relaying these data to NOAA's Pacific Tsunami Warning Center in real time.

The tsunami data indicated a nondestructive tsunami had been generated and evacuation of

Hawaii's coastline was unnecessary, saving the cost of a nonessential evacuation. The December

2004 Indian Ocean tsunami, which killed over 235,000 people, led to the development of the second

generation system, named DART II because of the two-way communication link from seafloor to

desktop. Another impact of this horrific tsunami was the appearance of many technologies that

were tought as being able to detect tsunamis in the deep ocean. Satellite-based technologies, radar-

based technologies, and acoustic-based technologies were identified as tsunami detection

technologies. However, these technologies could not measure tsunamis as accurately, reliably, and

within time constraints required to forecast tsunamis in real time. The pressure-measurement-

based DART technology prevailed as the most affordable and accurate technology to measure

tsunamis for realtime forecasting. By 2008, NOAA had expanded the original DART array from 6 to

39 stations in the Pacific and Atlantic oceans. Because the U.S. wanted to make this technology

available to all nations, NOAA licensed the patents for the technology and a commercial DART was

manufactured by a U.S. private company that currently provides DART technology to foreign

countries. Meanwhile, NOAA continued to make improvements to the original design, reducing

operating costs and improving reliability. By 2010, over 40 tsunamis had been measured using DART

technology and the third generation DART system had become a part of the operational global array.

The DART ETD (Easy to Deploy) is more affordable and does not require large ships or highly

specialized crew to deploy and maintain the operational arrays. These new developments in DART

technology hold promise for a global network of DART stations supporting a standardized global

tsunami warning system (Bernard, E., and C. Meinig, 2011).

Figure 11: Locations of DART systems (source: NOAA)


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When a tsunami event occurs, the first information available about the source of the

tsunami is based only on the available seismic information for the earthquake event. As the tsunami

wave propagates across the ocean and successively reaches the DART® systems, these systems

report sea level information measurements back to the Tsunami Warning Centers, where the

information is processed to produce a new and more refined estimate of the tsunami source. The

result is an increasingly accurate forecast of the tsunami that can be used to issue watches, warnings

or evacuations.

2.2.1 DART II System Components and Characteristics

A DART II system consists of two physical components: a tsunameter on the ocean floor and

a surface buoy with satellite telecommunications capability. The DART II systems have bi-directional

communication links and are thus able to send and receive data from the Tsunami Warning Center

and others via the Internet.

Figure 12: Context diagram showing a DART II system and the related telecommunication nodes (source: NOAA)

DART II performance characteristics are summarized below. These performance

characteristics helped to drive the research and development of the DART II system. Specific

engineering details about the tsunameter and the buoy follow.


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Table 1: DART II performance characteristics (source: NOAA)

The block diagram below shows how the components of a tsunameter function together.

The computer reads pressure readings, runs a tsunami detection algorithm, and sends and receives

commands and data to and from the buoy via an acoustic modem.

Figure 13: Tsunameter block diagram showing how the components interact (source: NOAA)


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2.2.2 Pressure Sensor

The DART II pressure sensor is a 0-10,000 psi model 410K Digiquartz® unit manufactured by

Paroscientific, Inc. The transducers use a very thin quartz crystal beam, electrically induced to

vibrate at its lowest resonant mode. The oscillator is attached to a Bourdon tube that is open on one

end to the ocean environment. The pressure sensor outputs two frequency-modulated square

waves, proportional to the ambient pressure and temperature. The temperature data is used to

compensate for the thermal effects on the pressure-sensing element.

2.2.3 Reciprocal Counter

The high resolution precision reciprocal counting circuit continuously measures the pressure

and temperature signals simultaneously, integrating them over the entire sampling window,

nominally set to 15 seconds. There is no dead period between the sampling windows. The circuit has

a sub-millimeter pressure and sub-millidegree temperature least-count resolution. The reference

frequency for the reciprocal counter is derived from a low power, very stable, 2.097152 MHz,

temperature-compensated crystal oscillator. A real time calendar-clock in the computer also uses

this reference for a time base. At the end of each sampling window, the computer reads the

pressure and temperature data and stores the data in a flash memory card. A 15-second sampling

period generates about 18 megabytes of data per year.

2.2.4 Computer

The embedded computer system in both the buoy and the tsunameter was designed around

the 32-bit, 3.3 volt Motorola 68332 microcontroller, and was programmed in C. It was built to be

energy efficient for long-term battery powered deployment. The computer has 4 Mb of flash

memory, a 12-bit A/D converter with 8 input channels, two RS232 channels, a hardware watchdog

timer, a real-time clock, and 512 bytes of RAM. The embedded computer implements and regulates

the primary functions of the surface and seafloor units: transmitting data communications, running

the tsunami detection algorithm, storing and retrieving water column heights, generating

checksums, and conducting automatic mode switching.

2.2.5 Acoustic Modem and Transducer

A Benthos ATM-880 Telesonar acoustic modem with an AT-421LF directional transducer has

a 40° conical beam which is used to transmit data between the tsunameter and the surface buoy.

Modems transmit digital data via MFSK modulated sound signals with options for redundancy and

convolutional coding. Transducers are baffled to minimize ambient noise from entering the receiver.


21

2.2.6 Tilt Sensor

Each tsunameter has a Geometrics 900-45 tilt sensor mounted in the base of one of the

housings. This is used to determine the orientation of the acoustic transducer when the system has

settled on the seafloor. If the tilt is greater than 10 degrees the tsunameter can be recovered and

redeployed. The watch circle of the surface buoy could carry it out of the acoustic projection cone

from the tsunameter if the angle from the vertical is too great.

2.2.7 Batteries

The tsunameter computer and pressure measurement system uses an Alkaline D-Cell battery

pack with a capacity of 1560 watt-hours. The acoustic modem in the tsunameter is powered by

similar battery packs that can deliver over 2,000 watt-hours of energy. These batteries are designed

to last for four years on the seafloor; however, this is based on assumptions about the number of

events that may occur and the volume of data request from the shore. Battery monitoring is

required to maximize the life of the system.

2.2.8 Tsunami Detection Algorithm

Each DART II tsunameter is designed to detect and report tsunamis autonomously. The

Tsunami Detection Algorithm works by first estimating the amplitudes of the pressure fluctuations

within the tsunami frequency band, and then testing these amplitudes against a threshold value. The

amplitudes are computed by subtracting predicted pressures from the observations, in which the

predictions closely match the tides and lower frequency fluctuations. If the amplitudes exceed the

threshold, the tsunameter goes into Event Mode to provide detailed information about the tsunami.

2.2.9 Reporting Modes

Tsunameters operate in one of two data reporting modes: A low power, scheduled

transmission mode called ““Standard Mode”” and a triggered event mode simply called ““Event

Mode””.

“Standard Mode” reports once every six hours. Information reported includes the average

water column height, battery voltages, status indicator, and a time stamp. These continuous

measurements provide assurance that the system is working correctly.

“Event Mode” reports events such as earthquakes and /or tsunamis when a detection

threshold is exceeded. The Tsunami Detection Algorithm triggers when measured and predicted

values differ by more than the threshold value. Waveform data are transmitted immediately (less

than a three-minute delay).

Tsunami waveform data continue to be transmitted every hour until the Tsunami Detection

Algorithm is in a non-triggered status. At this point the system returns to the Standard Mode.


22

2.2.10 Surface Buoy

The DART II surface buoy relays information and commands from the tsunameter and the

satellite network. The buoy contains two identical electronic systems to provide redundancy in case

one of the units fails. The Standard Mode transmissions are handled by both electronic systems on a

preset schedule. The Event Mode transmissions, due to their importance and urgency, are

immediately transmitted by both systems simultaneously.

The surface mooring uses a 2.5 m diameter fiberglass over foam disk buoy with a

displacement of 4000 kg. The mooring line is 19 millimeter eight-strand plaited nylon line with a

rated breaking strength of 7100 kg, and is deployed to maintain a tight watch circle, keeping the

buoy positioned within the cone of the acoustic transmission. In temperate areas where fish tend to

aggregate and bite lines, wire rope is use on the upper few hundred meters of the mooring.

Two downward-looking transducers are mounted on the buoy bridle at a depth of 1.5

meters below the sea surface. A multi layered baffle system of steel, lead, and syntactic foam shields

the transducers from noise, and cushions them with rubber pads for a soft mount.

Figure 14: Block diagram of DART II surface buoy (source: NOAA)

Further detailed information is given in Bernard and Meinig (2011).

2.3 MARMARA SEA OBO


23

KOERI started a new era in its observational capabilities by installing 5 sea floor observation

systems in the Sea of Marmara within the Sea Bottom Observatory Project supported by Turkish

Telecom, including broadband seismometers and differential pressuremeters, pressure transducer,

strong-motion sensor, hydrophone, temperature measurement device and flow meter. The first sea

bottom observation element was installed in December 2009 with real-time data transmission to

KOERI. The seismic component of the sea floor observation system improves the azimuthal and

spatial distribution of the existing NEMC network and reduces the early warning time and the

minimum magnitude threshold down to 1.0 in the Marmara Sea, especially close to the northern

branch of North Anatolian Fault (NAF), which is the most active fault zone in the Marmara Sea. As of

today, all observatories have been removed for instrument maintenance and improvements and are

expected to be deployed again in near future upon which real-time data communication to KOERI

will be re-established.

Figure 15: Elements and the architectural configuration of the SBO system in Marmara (source: KOERI)

Figure 16: Scenes from the deployment of the SBO system in Marmara Sea (source: KOERI)


24

Figure 17: Sea-bottom observation system in Marmara Sea (source: KOERI)

As mentioned above, all 5 SBO systems have been removed currently and are undergoing

maintenance to be re-deployed soon. Moreover, a denser network closer to the main faults in the

Marmara Sea would be extremely beneficial to increase the reliability and the operability of the

existing Earthquake Early Warning System in Istanbul.

As an industry first Guralp Systems Ltd. was recently awarded the contract for the design,

integration, and installation of a complete, multidisciplinary scientific ocean bottom observatory

(OBO). The turnkey system will be installed in the Marmara Sea, Turkey, to augment the existing

landbased networks for monitoring the seismicity along the North Anatolian Fault. The contract

comprises not only of the delivery of the sensors, digitizers and data transmission modules but also

of the laying of the optical cables and nodes for subsea data telemetry and building a land station to

receive and distribute the data.

The North Anatolian Fault (NAF) is one of the most active and dangerous earthquakes faults

in the world. Its seismicity is currently being monitored by a great number of land based stations,

many of them equipped with our CMG-3T, CMG-40T and CMG-5T sensors. As a substantial part of

the western section of the NAF runs through the Marmara Sea west of Istanbul a gap exists in the

network coverage. To close this gap Turkish Telecom in a joint project with Kandilli Observatory of

Bogazici University in Instanbul and Sentez Electronics Engineering Ltd. will install several integrated

ocean bottom observatories (OBO) in the Marmara Sea with cabled links to a central land station.

The deployment depth will vary between 400 and 1200 m water depth.

The location of the OBO is shown in the following Marmara sea map and the OBO network

consists of 5 separate stations.


25

Table 2: Details of the Marmara SBO Sites (source: KOERI)

Each OBO station is equipped with:

· CMG-3T broadband seismometer

· CMG-5T feedback accelerometer

· Hydrophone, 1 Hz broad band low noise hydrophone.

· differential pressure transducer (DPG) with Guralp Chopper stabilised amplifier · high

resolution temperature probe

· flow meter with 3D acoustic current meter,

· flux-gate compass and

· Two sets of tilt-meters, one on the sensor package the other on the sensor bunker. ·

Sensor bunker for protection and sensor installation purposes.

The analogue output of these sensors is interfaced to CMG-DM24 mkIII 24-bit digitisers. The

back end of the digitiser is connected to a CMG-DCM data communications module which transmits

the data via optical cable to a land station, which in turn is connected to the data acquisition system

at Kandilli Observatory via satellite communication.

Figure 18: An example of a local event recorded by the SBO but not by any land-based stations

(source: KOERI)


26

A typical large local event both recorded by strong motion and the broad-band sensors are shown in

the following seismogram.

Figure 19: A typical large local event both recorded by strong motion and the broadband sensors (source: KOERI)

The important feature of the 5 installed OBO stations is that the combined amplitude

dynamic range of both the broadband and the strong motions stations is more than 200 dB as shown

in the following plot.

Figure 20: The combined amplitude dynamic range of both the broadband and the strong motions

stations is more than 200 dB (source: KOERI)


27

In addition to the 5 existing broad band multidisciplinary OBO systems additional OBO

sensor systems will improve the event location and will enhance the capabilities of “ the early

warning” seismic network.

The proximity of extra OBO stations to each other will eliminate the requirement of

additional OBO stations to have very broadband long period response. It will be reasonable to have

mixed broad stations, long period broadband and mid period broad band stations with good high

frequency detection capability.

The OBO stations should all be multidisciplinary, as the likely optical communication method

will have more than adequate bandwidth to transmit the volume of data from the stations

The OBO stations can be composed of the following sensor instrumentation:

· Broad band 60 seconds to 200 Hz frequency response.

· (Few of the Broad band stations can be 120 to 100 Hz response).

· Additional High frequency sensors with response up to 500 Hz.

· Strong motion sensor with 4g capability.

· High resolution Tilt meter or equivalent at each station to detect the deformation

· High resolution temperature sensors capable of detecting 5 milli degree centigrade

resolution.

· High resolution three axis Magnetometer at selected stations OR all the stations.

· Broad band Hydrophone, I Hz response.

· Differential pressure gauge DPG with chopper stabilised operational amplifiers.

In addition to the multiple sensor technology the main requirement from the acquisition

system is to have low transmission latency for both the strong motion and the broad band sensors.

This is an essential requirement, as the data from the stations will be used as part of early warning

network.

The method of installation of the OBO sensor system ultimately determines the quality of

the recorded signals. Burial techniques are considered to be most effective method of coupling the

seismic sensors to the seabed. However, the expense of using ROV for burying seismic OBO system is

likely to be out of reach of many institutions. The next possible method that can be successful in

setting up a OBO station is to use a concrete dome to cover the sensor system at the bottom of the

sea. This method is established by GSL in 2010 as a viable and effective method of installing broad

band sensor.

The following photo shows GSL OBO sensor system being installed with an ROV. The sensor

is CMG-1T with levelling bowl and CMG-5T strong motion sensor.


28

Figure 21: GSL OBO sensor system being installed with an ROV (source: GURALP)

The following photo shows the inside of the sensor system. The same levelling system with CMG-1T

sensor and CMG-5T.

Figure 22: Inside of the sensor system (source: GURALP)


29

Figure 23: The Neptune OBO sensor being installed with ROV, buried for good coupling and long-term stability (source: GURALP)

Figure 24: Neptune OBO sensors being tested prior to delivery at GSL vault (source: GURALP)

The installation method also determines the type of casing that will be used for the

complete station. There are various sensor packages that GSL have designed both for ROV

installation and for free fall.

The following photo shows a sensor system that can be used with ROV installation or as part

of concrete domed OBO station. The very board band Antares (360 second to 100 Hz), 200 dB


30

dynamic range sensor system with internal acquisition and data transmission system is being

installed with ROV at 2300 meters depth.

Figure 25: sensor system that can be used with ROV installation or as part of concrete domed OBO

station (source: GURALP)

Figure 26: Covering an OBO sensor with a dome without burying is an effective way to install a

broad-band sensors system (source: GURALP)

The data form these installations can be made available and can be found in the literature.

The method used in the Sea of Marmara is a simple method of releasing the station package with

the cabling and the concrete dome as shown following photo.

Figure 27: Releasing the station package with the cabling and the concrete dome (source: GURALP)


31

2.3.1 Detecting Small Earthquakes with OBS

This section is based on a technical report provided by GURALP to KOERI. Many local

Marmara events have been recorded even events that have not been recorded by the land based

stations have been recorded by the OBO stations. In this section, several examples of

microearthquake recordings under various noise conditions will be presented. In all figures, the

green trace is the vertical, red is N/S and blue is E/W.

On 6 Feb 11 at 13:05:19 UTC a microearthquake occurred in the Southwestern part of the

Sea of Marmara. It was detected by the land network and assigned a magnitude of 1.8. This event

was recorded well by two of the OBS, station 3 and 4. Their recordings, filtered with a high pass with

a corner at 3 Hz are shown in Figure 28.

Figure 28: Thirty seconds of data shown (source: GURALP)

In Table 3 a summary of some of the readings taken from the recording shown in Figure 28.

Table 3: Phase parameters related to the recordings at OBO-4 and OBO-3 sites for the 6 Feb 11 at

13:05:19 UTC microearthquake occurred in the Southwestern part of the Sea of Marmara (source:

GURALP)

Station Distance

(km)

Azimuth P-Travel-

time (s)

S-Travel-

time (s)

P-Velocity

(km/s)

S-Velocity

(km/s)

OBO-4 35 179 8.7 14.8 4.02 2.36

OBO-3 55 222 12.8 21.2 4.29 2.59


32

While the seismic noise conditions were rather quiet on 6 Feb 11, 22 Jan 11 was a much

noisier day. At 14:44:48 UTC another event with Ml=1.8 occurred, which was recorded by the land

network. Due to the noisier sea conditions, it was only registered by OBS-Station 4. Even though its

epicenter was only 11 km to the SE of the station, the recording is much less clear when compared

to the event shown in figure 3(g1). Figure 4(g3) shows the event of 22 Jan 11 at OBO-4, again filtered

with a high pass with a corner at 3 Hz. Note that the S-P time is 3.7 sec, which is rather long for an

event at an epicentral distance of 11 km.

Figure 29: Ten seconds of data shown (source: GURALP)

The noise conditions were much quieter two days prior to the event shown in figure 4(g3).

On that day OBO-4 recorded a Ml=1.5 event 34.5 km to the SSW of the station.

Figure 30: Twenty seconds of data shown (source: GURALP)


33

In Figure 30 the unfiltered broadband data of the Ml=1.5 event is shown. While the S-onset

shows very clearly on both horizontal components, the P-onset is hidden in the noise. However, it

becomes much clearer, when we pass the data through a high pass filter with a 3 Hz corner, as

shown in figure 6. Please note that in figure 6 we shifted the data segment shown to the right as

compared to figure 5 in order to show how the P-onset clearly sticks out from the pre-event noise.

Figure 31: Twenty seconds of data shown (source: GURALP)

The magnitude threshold of the land based network for events in the Sea of Marmara is

approximately Ml=1.5. The OBS network has recorded many smaller events, however mostly only on

one station. That makes the determination of the hypocenter and thereby the calculation of a

magnitude impossible. One such tiny event, which was not detected by the routine analysis of the

Turkish land based network, was registered at OBS-Station 2 on 22 Nov 10. Figure 7 (g6) shows the

unfiltered data with an S-P time of only 0.7 sec. Using the velocity values of table 2 (g7), this

corresponded to a distance of the hypocenter from the station of approximately 4km. Although we

don't know the magnitude, we calculated the maximum amplitude of the true ground motion at 125

mmeter/sec on the vertical component.

Figure 32: Three seconds of data shown (source: GURALP)


34

An example of an even smaller event is shown in Figure 33. It occurred on 27 Feb 11 and,

again, was not recorded by the land based network. Its S-P time is only 0.17 sec, leading to a

distance of approximately 1 km. Note the ringing coda after the main event. The maximum

amplitude is again on the vertical component with a true ground velocity of 33 mmeter/sec. The

data shown in Figure 33 are filtered with a high pass with a 3 Hz corner. There is a multitude of such

recordings of very small events in the data streaming continuously from the Marmara OBS network.

Figure 33: Five seconds of data shown (source: GURALP)

2.4 Neutrino Mediterranean Observatory Submarine Network 1

The NEMO-SN1 (Neutrino Mediterranean Observatory <http://nemoweb.lns.infn.it/> -

Submarine Network 1) seafloor observatory is located in the central Mediterranean Sea, Western

Ionian Sea, off Eastern Sicily Island (Southern Italy) 37.55°N 15.4°E at 2036 m water depth, 25 km

from the harbour of the city of Catania. It is a prototype of a cabled deep-sea multiparameter

observatory and the first operating with real-time data transmission in Europe since 2005. NEMO-

SN1 is also the first-established node of EMSO <http://emso-eu.org/> (European Multidisciplinary

Seafloor Observatory), one of the incoming European large-scale research infrastructure included

since 2006 in the Roadmap of the ESFRI <http://cordis.europa.eu/esfri/roadmap.htm> (European

Strategy Forum on Research Infrastructures). EMSO will specifically address long-term monitoring of

environmental processes related to Marine Ecosystems, Climate Change and Geo- hazards.

The observatory was deployed the first time in stand-alone mode in 2002-2003 (project

GNDT1). It was upgraded and cabled and operated in 2005-2008 (project GNDT2). After

refurbishment it was redeployed in 2012-2013 (SMO1 NEMO-SN1). Currently redeployment is

expected in summer of 2015.

http://emso-eu.org/

http://cordis.europa.eu/esfri/roadmap.htm


35

Early tsunami detection is performed in real-time at the NEMO-SN1 site. To speed up

detection a tsunami detector prototype has been developed with a new Tsunami Detection

Algorithm (TDA). This multiparameter detection method is based on data from pressure sensors and

seismometers (Chierici et al., 2012). The seafloor segment of the tsunameter is composed of bottom

pressure sensor, seismometer, accelerometer, and a CPUwhich analyses data acquired from the

sensors. The high efficiency real-time TDA (Chierici et al., 2012), which runs on the CPU, is able to

detect tsunami parent signals down to a few millimetres of amplitude.

Figure 34: Location of Neutrino Mediterranean Observatory Submarine Network 1

Seismological instruments on board used for early tsunami detection:

- seismometer Guralp CMG-1T, 0.0027 Hz to 50 Hz bandwidth and 100 Hz sampling rate.

- OAS E2PD hydrophone 100 Hz sampling rate

- digitizer Guralp DM-24 (24 bits) for both seismometer and OAS hydrophone

- Paroscientific absolute pressure gauge depth sensor (model 8CB-4000), sampling interval of 15 s,

resolution 1 Pa (10–4 dbar)

- SMID hydrophone SMID DT405D, sampling rate 2 kHz, resolution of 10–2 Pa, passband from 50

mHz to 1 kHz.

2.4 POSEIDON PYLOS

The Pylos site (Southern Ionian Sea) is designed as open-ocean monitoring systems that can

provide continuous information for physical parameters in the upper thermocline, bio-chemical


36

parameters in the euphotic zone and air-sea interaction parameters at the sea-surface level. The

Pylos site is deployed at 36.8° N 21.6° E at a depth of 1660m in an area with complex hydrology

where intermediate and dense water formation takes place (CIW, CDW) while water masses formed

in the Levantine and the northern Aegean Sea meet and interact with those locally produced. The

platform which has been upgraded recently through POSEIDON II project hosts a variety of different

sensors measuring meteorological, physical and biochemical parameters. The buoy used at these

sites is a Seawatch-Wavescan type which is a multi-parametric instrumentation platform and

suitable for deployment in deep offshore locations (Furgo OCEANOR www.oceanor.no). The two

stations are programmed to collect the data every three (3) hours and upon collection to transmit

them to the receiving station.

The sea-bed observatory lies on the sea bottom and it has built-in sensors capable of recording at a

high resolution the water column pressure, temperature and salinity. The communication between

the platform and the surface buoy is achieved through hydro-acoustic modems. The coupling of a

sea bottom observing platform with a multi-parametric mooring, creates new opportunities of

monitoring the ocean not only through air-sea interaction related parameters or the first few

hundred meters of the water column data, but also through geo-physical and bio-chemical data of

the deep sea basin that are now becoming available.

The POSEIDON-Pylos observatory is located in the cross road of Adriatic and Eastern Mediterranean

basins in a very geologically active area with high number of earthquakes and landslides as well as a

potential source of tsunamis that might affect the Eastern Mediterranean Sea.The POSEIDON PYLOS

is carrying out

– meteorological observations (Wind speed and direction, temperature, pressure),

– surface ocean (Wave height-period-direction, salinity, temperature, current speed and direction),

– ocean interior (Salinity, temperature at 20, 50, 75, 100, 250 400, 600, 1000m)

– seafloor (Salinity, temperature, depth, dissolved oxygen).

– Tsunami monitoring

It has been upgraded in 2008 with the addition of an autonomous seabed platform within the

framework EuroSITES Project.

Figure 35: Location of the POSEIDON-Pylos site (left) and deployment of the seabed platform at the

POSEIDON-Pylos site in November 2008 (source: HCMR)


37

Figure 36: Further figures from POSEIDON-Pylos site deployment (source: HCMR)

The platform was enriched with close-to-seabed measurements the observing capabilities of

the POSEIDON-Pylos site that continues its standard water column (0-1000m) and air-sea interaction

observations. The communication between the seabed platform and the surface buoy is carried out

through acoustic modems and allows near real time transmission of the data. The platform is

equipped with a high accuracy pressure sensor and the necessary software for real time signal

analysis for possible Tsunami detection, as well as an SBE-16 for temperature and salinity

measurements. During the pilot operation that followed the deployment of the platform, two

problems have been identified: erroneous pressure data leading to false Tsunami alarms and events

of unsuccessful communication between the platform and the surface buoy. The platform was

recovered in March 2009 in order to continue laboratory tests and resolve these problems as well as

to carry other minor software upgrades (new bios etc).

Following communication with the pressure sensor manufacturer, the erroneous data have

been attributed to gas bubbles trapped into the instrument (in the tubing between the pressure port

in the lid to the pressure transducer). The system has been sent to the platform manufacturer for

further lab and in-situ tests. The communication problems between the platform and the buoy are

attributed to shadowing effects of seabed anomalies. A more appropriate area with smaller

topographic anomalies was due to be selected during the next deployment of the seabed platform in

early December 2009.

2.5 TSUNAMI EARLY WARNING SYSTEM IN ROMANIA

The tsunami early warning system for Romania was accomplished by the National Institute

for Earth Physics (NIEP) in the framework of the international project “Set-up and implementation of

key core components of a regional early-warning system for marine geohazards of risk to the

Romanian-Bulgarian Black Sea coastal area - MARINEGEOHAZARDS” in collaboration with the

National Institute for Marine Geology and Geoecology (GeoEcoMar), the Institute of Oceanology of

the Bulgarian Academy of Science and the Geological Institute of the Bulgarian Academy of Science.

The warning system contains both onshore and offshore different types of equipments, some of the


38

existing before this project, some of them installed and developed during MARINEGEOHAZARDS.

Mostly, the onshore equipment belongs to NIEP and is maintained by the personnel from the

Dobrogea Seismological Observatory in Eforie, and the offshore equipment belongs to GeoEcoMar

and to the Bulgarian Institutes. Mostly, the onshore equipment belongs to NIEP and is maintained by

the personnel from the Dobrogea Seismological Observatory in Eforie, and the offshore equipment

belongs to GeoEcoMar and to the Bulgarian Institutes.

The offshore equipment consists a system of 5 Marine Buoys and Underwater Tsunami

Modules installed at different sites.

Figure 37: Buoys and Tsunami Modules installation sites

Table 4: Buoys and Tsunami Modules installation positions

Each one of the buoys is a Surface Relay Buoy (SRB) is also called semi-spar buoy. Its scheme is

shown below.


39

Figure 38: Surface Relay Buoy (SRB) scheme

The sensors of the SRB are the following: Meteorological station, Subsurface Instrument Package,

Heading sensor and Diagnostic Status Sensors. The Meteorological Station is measuring the following

parameters: pressure, temperature, relative humidity, wind speed and wind direction. The

Subsurface Instrument Package is composed of datalogger model Seaguard RCM (SW) for 300 m of

depth, and has the specifications of the sensors structured in the table below.

Table 5: Subsurface Instrumented Package Specifications


40

The Heading and Tilt Sensor is useful to monitor the buoys tilts and rotations. The heading

measurement is compensated for tilt angles up to 40 degrees. The Status Sensors are

integrated is a custom electric board with serial interface. These sensors allow to monitor the

“technical status” of the system. Its components are: two voltage and current sensors, one

temperature sensor, one pressure sensor and one weter detector sensor.

CHAPTER 3: CASE STUDY – POSSIBLE LOCATIONS FOR THE IMPLEMENTATION

OF A DONET-LIKE SYSTEM IN TURKEY

Five locations have been identified for the possible establishment of a DONET-like system in

Turkey. These are Marmara Sea, İğnede and Sinop as the possible Nuclear Power Plant (NPP)

locations in Black Sea, Akkuyu NPP in the Eastern Mediterranean and Fethiye Region at the junction

of Aegaen – East Mediterranean Sea facing the Hellenic Arch, the most active seismic region in the

whole Mediterranean. The deepest bathymetry levels within the regions selected are approximately

1200 m (Marmara), 2100m (İğneada NPP), 2200 m (Sinop NPP), 1000 m (Akkuyu NPP) and 1000 m

(Fethiye Region) excluding foreign sea-territories.

Figure 39: Selected locations for the possible establishment of a DONET-like system in Turkey are

shown on the map: İğneada NPP and Sinop NPP in Black Sea, Marmara (M) Region, Akkuyu NPP in


41

the Eastern Mediterranean and Rhodes-Fethiye (R-F) Region at the junction of Aegaen and the

Eastern Mediterranean. Seismicity of Turkey and its surroundings (M > 4) is given in the background.

Figure 40: Outline of the proposed DONET-like MARMARA Observation Network

Table 6: Cable lengths of the proposed DONET-like MARMARA Observation Network


42

CHAPTER 4: CONCLUSIONS

The NEAM region is perhaps in its early days in terms of submarine sensor networks used for

the purposes of the Tsunami Early Warning. Despite the fact that several systems are in place, none

of these systems can be considered as constituting the backbone of the operational systems they

belong to. On the other hand, sea bottom seismological observations are of crucial importance to

both monitor earthquake and tsunami activity. This deliverable provides a summary of selected

submarine networks in connection with Tsunami Early Warning Systems while providing a de facto

comparison between what is currently available in the Euro-Mediterranean Region and around the

globe. Several systems, such as DONET (JMA), DART (NOAA), Marmara OBO (KOERI), Poseidon Pylos

(HCMR-NOA), and Neutrino (Italy) have been discussed. Special emphasis is given to Marmara OBO

due to the fact that the system is operated by KOERI. A DONET type system is found to be most

beneficial to the TWS in the Euro-Mediterranean region as the ability to record both earthquake and

tsunami signals at the same observation points should be considered. This is a necessity of the fact

that the tsunami sources are located in a very near distance to the coast, especially in the

Mediterranean basin. To address this, this deliverable proposes several locations around Turkey for

the possible deployment of submarine sensor networks. However, this deliverable does address

neither critical issues such as financial and operational implications nor the feasibility of these

systems concerning their deployment and maintenance. Internally, this deliverable is expected to

provide input to “D6.31 Definition of optimum sensor locations”. Externally, this deliverable is

expected to provide input to WP7, specifically to “D7.28 Tsunami forecast capabilities in the NEAM

region (M27)”.


43

REFERENCES

Allen,R.M., Kanamori.H. (2003). The potential for earthquake early warning in southern California,

Science, 300 :786–89.

Bernard, E., and C. Meinig (2011): History and future of deep-ocean tsunami measurements.

In Proceedings of Oceans' 11 MTS/IEEE, Kona, IEEE, Piscataway, NJ, 19–22 September 2011, No.

6106894, 7 pp.

Charvis, P., Nolet, G., Deschamps, A. and Hello, Y., (2009) Why do we need submarine seismometers? http://www.esonet-noe.org/content/download/20810/301130/file/VISO_Conf_Charvis09_low.pdf Chierici, Francesco. (2012). Pressure gauge dataset (Paroscientific 8CB-4000-I @ 1 sample / 15 sec)

from INAF/NEMO-SN1 seafloor platform during SMO project in Western Ionian Sea site (East Sicily),

part of EMSO network.

DART® (Deep-ocean Assessment and Reporting of Tsunamis) http://nctr.pmel.noaa.gov/Dart/ DONET (Dense Oceanfloor Network System for Earthquakes and Tsunamis) https://www.jamstec.go.jp/donet/e/ http://www.eurosites.info/nestor.php http://outreach.eurosites.info/outreach/DeepOceans/station.php?id=12&page_inc=gallery GURALP, C. (2014), Detecting small earthquakes with OBS, GURALP Technical Report

Meinig, C., Stalin, S.E., Nakamura, A.I., B., Hugh, (2005), Real-Time Deep-Ocean Tsunami Measuring, Monitoring, and Reporting System:The NOAA DART II Description and Disclosure NEAMTWS-IOUG Interim Operational Users Guide for the Tsunami Early Warning and Mitigation System in the North-eastern Atlantic, the Mediterranean and Connected Seas (NEAMTWS) Version 2.00 Approved by ICG/NEAMTWS-VIII (Santander, 22-24 November 2011)

http://www.esonet-noe.org/content/download/20810/301130/file/VISO_Conf_Charvis09_low.pdf

http://nctr.pmel.noaa.gov/Dart/

https://www.jamstec.go.jp/donet/e/

http://www.eurosites.info/nestor.php

Documents

ASTARTE · Abstract (for dissemination) This deliverable provides a summary of selected submarine networks in connection with Tsunami Early Warning Systems while providing a de facto