Observatories and Research Facilities for EUropean SeismologyVolume 1, no 2 April 1999 Orfeus Newsletter

ORFEUS Electronic NewsletterThe Orfeus Electronic Newsletter aims at disseminating rapidly relevant information to theOrfeus community within the European-Mediterranean area. You are encouraged to submitcontributions in the form of an article, news or announcements according to the authorsinstructions to Orfeus.

Articles and NewsEDUSEIS, An EDUcational SEISmological EuropeanNetwork: 13 (122 kB)Jean VirieuxA European Educational seismograph network initiative.

Modernizing the Danish Network: 14 (81 kB)Tine B. Larsen and Peter VossNew BB stations in Denmark and Greenland.

The GEOSCOPE Program: 15 (109 kB)Geneviève Roult and Jean-Paul MontagnerThe global BB and VBB network; data access and newdevelopments.

The Regional Data Center at the SeismologicalCentral Observatory Gräfenberg SZGRF: 16 (147 kB)Klaus StammlerGermany: GRF and GRSN BB data on-line available.

CTBTO: The International Monitoring System: 17 (122kB)Roderick StewartSpecifics on its seismological operation and theProvisional Technical Secretariat (PTS). Includes the IMSStation Specifications.

Short notesFDSN working group B meeting: 18(27kB)Waveform data exchange issues in aglobal context.

AnnouncementsORFEUS announcements: 19 (5 kB)

Orfeus at IUGG99 (July):WG1 - Station siting: July 24WG2 - Technical support: July 28WG4 - Software: July 25ORFEUS work meeting: July 27

ORFEUS Wilber and JavaSeismogram Viewer.

Seismo-edu - Educational links

page 12Copyright © 2000. Orfeus. All rights reserved.

Note: Hyperlinks and email addresses are live and active at the time of publication but cannot beguaranteed by ORFEUS for indefinite future use.

Please contact Torild van Eck to (un)subscribe to the Orfeus Newsletter or request printed copies (onlyparticipants).

Observatories and Research Facilities for EUropean SeismologyVolume 1, no 2 April 1999 Orfeus Newsletter

EDUSEIS, An EDUcational SEISmological European Network

Jean Virieux

FranceCentre International de Valbonne, Sophia-Antipolis: contact Jean-Luc BerenguerResearch Laboratory Géosciences Azur, Sophia-Antipolis: contact Jean Virieux or Jean VirieuxResearch Laboratory Tectonophysics, Montpellier: contact Marc Daignières or Erik DoerflingerItaliaFondazione IDIS-Città della Scienza, Napoli: contact Anne-Marie Bruyas or Angela PalmaDipartimento di Scienze Fisiche, Napoli: contact Antonella Bobbio or Aldo ZolloNetherlandsOrfeus Data Center, De Bilt: contact Bernard Dost or Torild van EckPossible future developments: Luis Matias, Portugal ; Jesus Ibanez, Spain ; Costas Papazachos, Greece.

Introduction - Objectives - Network - Event examples - Perspectives

Introduction

In the footsteps of the United States Princeton Education Physics Project, PEPP, thefundamental aim of our Educational Seismological Project, EDUSEIS, is a confrontation ofschool students with the current practice of scientific data acquisition and management. Recentnetworking evolutions make available in the classroom data and tools which were only used inresearch laboratories.

The rapid growth of digital electronics is just as quickly revolutionisin= g scientific practice,though, even among scientists, there are few who really appreciate how fundamental thisrevolution is. Technology is being driven more by an economic impetus than by the need to solveimportant problems - be they scientific or social - and scientists often have had to becomereactive rather than proactive to technology.

This, of course, is even more true for the educational environment. While industry debates thelaunching of communication systems comprising hundreds of satellites, and the Internet is soonlikely to become to the average household what the telephone is now, teachers have obviousdifficulty to adapt. This is, in particular, true for secondary education. Many schools now offerbasic courses in the use of computers, word processing packages, or even simple programminglanguages. But does this give the students a sense of how chemistry, physics, biology areaffected by the digital revolution? Does it give the students an idea of the power of informationtechnology? Since the latter can be used and misused, the health of our democratic societiesmay ultimately depend on how well we teach our children to cope with information technology.

A second fundamental change is the rapid growth of multidisciplinary studies of the environment.Increased population density has made natural hazards such as earthquakes, volcanic eruptionsand hurricanes more costly both in terms of human life and in terms of economic damage.

How the education system should react to such changes is not very clear. Some aspects havehardly even been debated. Meanwhile, the gap between what is taught in schools and what isdone in the real world is growing rather than diminishing. This is a dangerous situation. Anunder-educated population is at the mercy of those who control the information technology.

Our experimental project will make students active participants rather than passive consumersand the selected vehicle for such training is seismological observation, which offers a number ofclear advantages: earthquakes are spectacular and 'in the news', hence likely to attract theattention of the students; the digital observation of seismic waves involves large quantities ofdata but not so large that it cannot be handled by personal computers of the type now acquiredby many schools; the development of cheaper instrumentation now allows schools to participateactively in data acquisition, using the Internet to share data; the analysis of seismogramsinvolves many sciences, and may be illustrative in classes of physics, mathematics, geography,geology, and social science.

PEPP in United States of America and EduSeis in Europe are based on recent development ofnew technologies which allow the use of high quality and low-cost seismic instrumentation inschools. The construction of the project EduSeis is different from the American PEPP experienceon many aspects related to the social differences one can find between Europe and USA.

General objectives of the project

a) Open schools towards their environment: make young people aware to natural hazards.Involving the high schools in management of seismic network according to the different schoolorientation will lead to the creation of a dense network of seismic "observatories" which willincrease the data available for research in the field of Earth Science. This work will result to beextremely interesting and useful to the social and scientific community.Thus, the project has a remarkable impact on the prevention of the seismic risk, through a strongeffect of awakening and involvement of the schools, of the general public in museums; ofstudents, teachers and their families. Although in Europe and, in particular in the Mediterraneanarea, the risk of strong earthquakes exists, the politics of information and awakening to theseismic prevention are still insufficient in comparison with analogous initiatives undertaken inother seismic regions in the world (such as for example Japan, Western United States).

b) Promotion of news technologies in schools.The co-ordination and follow-up of the seismic station require also the experimental use of newstechnologies (gathering the information, extraction of data and diffusion as well ascommunication of these data). The data and scientific information exchange between schools,museums and research centres inside the European network mean for students to be friendlywith the modern, computer based systems of archives, access, consultation and promulgation ofthe information represented by the Internet network.

c) Promotion of experimental sciences in schools.The co-ordination and follow-up of the seismic station in schools request to young students todevelop specific know-how and skills in experimental sciences (measurements, observations,formulation of working hypothesis and verification of these hypothesis, gathering andorganisation of data, presentation of ideas and their discussion with other people).The skills required for the implementation and the management of the monitoring station concernseveral matters such as, for example, Physics/Mathematics (waves, filters, transducers, ...),Earth Sciences (seismic waves propagation, interpretation of seismic events, ...), ComputerSciences (data processing with "ad hoc" developped software for the acquisition on real time ofseismic data or more general programs for selecting, exchanging information), Foreignlanguages training (information on the data bank, exchanges between students from differentcountries).

d) Managing the complexity of natural phenomenon through an interdisciplinaryapproach.Seismic events are not easy to understand. Their discriminations with other natural events aswell as artificial noises are only possible with long-term training with specific learning strategies.Students will appreciate the necessary global and complete overview for such understanding.

e) Teaching young people the sense of responsibility and working in groupThe follow-up of the seismic station, and the co-ordination of many activities around it, will help totest educational activities based on a co-operative way of learning and teaching, as well as theenthusiasm of students, their sense of responsibility and their tenacity.

f) Construction of a partnership between regional and international institutions in the fieldof scientific research, education and awarenessFirst of all, the project aims to establish a direct relationship between the scientists on one side,teachers and school students on the other one. This relationship, thanks to scientificcommunicators and educators, will involve schools and as research institutes, but also localorganisations, institutions, associations in scientific research activities and in countydevelopment choices.

Description of the EDUSEIS Network

This educational network has all the important components of a modern network for theacquisition of environmental information. Our main technological effort is in that direction. Theseismic station, PC-ACQUI, records the vibration of the ground. The seismic regional center,PC-CONTROL, collects these data through telephone lines every night (Figure 1). Finally, anEuropean database center will organise and archive the data.

Figure 1: Regional link between stations in schools and the regional center for the EduSeis network

We have selected broadband sensors as the Guralp or the PMD. They are sensors selected byPEPP but our management is entirely different. These instruments have a flat response between30 s and 0.2 s (Figure 2)

These sensors provide an electric signal which is digitized by a computer card (PC-NUM)plugged into a personal computer which is the cheapest controlling system one can think about.The card has been developped by Agecodagis and it is based on HARRIS HI7190 24 bitsconverters. This card includes a GPS Rockwell minicard for the absolute time recording, anessential critical data for seismic analysis. Careful handling of time is performed for an accuracylower than 1 msec. Data are recorded locally in a cyclic buffer with an autonomy of around 15days.

Figure 2: Different elements of the seismic station for the CIV school in France. The sensor on the left, therecording station in the middle and the GPS antenna on the right.

This seismic station is linked by a modem with standard telephone line to the PC-CONTROL.This PC-CONTROL is on the Internet and collects information of world-wide seismic events fromobservatories. From the distance between the seismic event and the seismic school station, apost-triggering is performed automatically with a time window extracted at the station dependingon the magnitude of the event. These signals are retrieved from each station during the night andconverted to a standard SAC format. This format is used for plotting the signal through anybrowser which can handle Java language. Conversion into the PEPP format is also performedand these files are provided through ftp for local applications in any school connected to theInternet.

Seismic event examples

Since 1998, events have been recorded in France and in Italy. This prototype running in 1997through an experimental test at the CIV school has been replaced by standard stations installedin Alpes Maritimes, Languedoc-Roussillon as well as Napoli area. Two examples are shown for aregional event and a teleseismic event. Other examples are freely availble at ther WEB sites.

Figure 3: Seismic event located in the Genova Golf.

Figure 4: Seismic event from Antartica. It has taken around 12 minutes for reaching the station CIV.

Perspectives

During the year 1999, the actual seismic network system will be tested before any furtherextension. The automatic retrieval of the data will be tested when a noticeable number of stationsare available. Groups from Greece, Spain and Portugal are interested to join this experimentalnetwork, while extensions in France and in Italy will take place. Technological improvements willoccur at the different levels of the seismic school network. New sensors will be tested, while theseismic station could be connected directly to the Internet instead of the actual telephone link.The key of success in the future will reside in our capacity of extending the network throughmany countries in Europe.

page 13Copyright © 1999. Orfeus. All rights reserved.

Observatories and Research Facilities for EUropean SeismologyVolume 1, no 2 April 1999 Orfeus Newsletter

Modernizing the Danish Network

Tine B. Larsen and Peter Voss

National Survey and Cadastre (KMS), DK-2400 Copenhagen NV, Denmark

Introduction - Requirements - InstrumentationData communication - Data availability - Transition process - Future

Introduction

The Danish seismological network is currently highly heterogeneous with seismometers rangingfrom WWSSN over S-13 to STS-1 that are connected to a mixture of digital and analog recordingsystems. In early 1998 extra funds were made available for upgrading the stations in Denmarkand Greenland in order to obtain a more homogeneous, fully digital network. The objective of thisletter is to outline the process of modernizing an entire, although small, network with the hope toinspire and encourage other network operators planning similar undertakings.

Figure 1. Stations in Denmark

Requirements for the new system

The very first step of the process was to envision the look and feel of the upgraded network. Thislead to the formulation of the following list of requirements:

Broadband seismographs. The added possibilities offered by broadband seismographsover short-period instruments, combined with a long Danish tradition for surface wavestudies made this an easy choice.

●

Large local ringbuffers. Data must be saved locally at each station, even if the data istransferred continuously to the main office. Too many times data has been lost due toproblems with the phone lines, and the price of large hard disks has become quitemanageable.

●

Local time stamping. In the current system data from several stations are transferredover dedicated phone lines to the KMS office, where the time stamps are added. Thisprocedure is incompatible with local storage of the data.

●

Dial-up access to all stations. It is not feasible to transfer data from all stations in thenetwork over phone lines on a daily basis, but it should be possible to call up any stationand transfer chunks of data whenever desired.

●

Continuous data. Local Danish earthquakes usually do not stand out significantly from thebackground noise and could too easily be overlooked by an automatic event picker. It istherefore necessary to save continuous data.

●

Historical link. A connection should be established between the old data and the datafrom the new instruments. It is important to know how the new registrations relate to theold ones, otherwise the data will be less useful.

●

Instrument response. Only companies willing and able to provide complete informationabout data formats and instrument response ahead of the purchase would be considered.

●

Based on these requirements, a call for proposals was sent out to a handful of companies. Thecompanies were asked to delineate how their equipment would fit into our upgrade strategy,which made a final purchase decision easier.

Instrumentation and software

The Streckeisen STS-2 seismometer was chosen due to its wide frequency band, goodreputation and widespread use among colleagues. To digitize the data the Nanometrics HRD24was chosen owing to considerations of price, quality and customer support. The HRD24 also hasa built-in GPS for timing and it is compatible with the University of Bergen SEISLOG acquisitionsoftware, which we decided to use. The SEISLOG system has the advantage that it is free, and itis used by some of our close neighbors, both in Norway and at the British Geological Survey.The SEISLOG and SEISAN packages will be supplemented by some KMS developed PCsoftware.

Data communication

Data transfer between the seismological stations and the KMS is complicated by the fact that theKMS computer systems are protected by a firewall. It is therefore impossible to make directdial-up connections between the stations and the office computers. Instead we are setting up asystem where we can call the stations in Denmark over ISDN lines and transfer the data througha central KMS dial-up point to the main computer system for processing. Two stations, COP andMUD, will keep on sending data continuously to the KMS office over dedicated phone lines, whilethe remaining stations will be used on a dial-up basis. Continuous data from the dial-up stationswill be saved on CD-ROM or DAT and mailed to the KMS on a regular basis.

The situation in Greenland is more complicated. While ISDN is available in Greenland, the fasttransfer rates can be obtained only within Greenland and not across the Atlantic to Denmark.Given the high cost of phone calls to Greenland, it is not feasible to transfer data on a regularbasis over phone lines. Instead we are working on an Internet solution, where the stations inGreenland would connect locally to the Internet, so that we may ftp the data from Greenland atthe cost of a local phone call. The technical details of this solution have not been worked out yet.

Data availability

Data from the Danish network (old system only) is available by autodrm (autodrm@kms.dk), andthe weekly bulletins can be found on the KMS seismology web page under Seismic service.

Figure 2. stations in Greenland.

The transition process

Before the Danish seismological network is fully upgraded and the old instruments are phasedout, a final calibration will be performed on all the current seismographs. In this way the olderdata is well-documented and can be used later. The method chosen is developed by Prof.Erhard Wielandt and was presented at the ORFEUS workshop in Prague, November 1998. Forour calibration we used his software, CALEX. The method is a relative calibration of eachseismic sensor where the calibration signal is compared with a known reference signal. Thecalibration has been performed on the STS-1 seismometers at the COP station, but not withoutdifficulties, as it turned out that the old Nanometrics RD3 digitizer had been modified with ahigh-pass filter. This experience emphasizes the importance of calibrating old equipment, whenno-one can remember how it was modified.

Looking to the future

Four STS-2 seismometers and four HRD24 digitizers were delivered in December 1998, and theinstruments are planned to be in operation at MUD, BSD and SCO by fall 1999. The new stationin Narsarsuaq will be slightly delayed due to a field project, but the station is expected to be fullyoperational sometime in 2000. The old systems will be shut down by the end of 1999.

Acknowledgement

We would like to thank our colleagues at KMS who participate very actively in this process, JensHavskov and Terje Utheim, University of Bergen, Winfried Hanka, GFZ, Erhard Wielandt,University of Stuttgart, Jure Ravnik, Geophysical Survey of Slovenia, and ORFEUS forinvaluable help and numerous discussions.

page 14Copyright © 1999. Orfeus. All rights reserved.

Observatories and Research Facilities for EUropean SeismologyVolume 1, no 2 April 1999 Orfeus Newsletter

The GEOSCOPE Program

Geneviève Roult and Jean-Paul Montagner

Département de Sismologie, Institut de Physique du Globe, 4 Place Jussieu, 75252 Paris-Cedex 05, France

Abstract - Present status - Data Center -Activities and facilities - Conclusion

Abstract

The purpose of the GEOSCOPE program was the installation of about 20 stations well distributedworldwide (in particular in the southern hemisphere), in the standard configuration defined by the FDSN(VBB 24 bit, continuous recording at 20 samples/s). The installation is almost complete. The effort hasbeen focused on the accessibility of data from our Data Center. Data can be obtained either on linethrough the WWW server, or through our anonymous ftp, or through CDROM production or through theSPYDER system for large earthquakes. In the near future easier ways will be available, such asautoDRM ( automatic Data Request Management) and NetDC requests (protocol proposed by the IRISDMC).

Present status of the network

The Data Center of Paris is archiving data from 29 stations :twenty-six permanent « Geoscope » stations

20 Stations maintained by the Technical Division of IPGP (Saint-Maur, near Paris). All ofthem are operating in VBB configuration (BH channel at 20 sps, LH channel at 1 sps, VHchannel at 0.1 sps).

❍

4 stations maintained by EOST (Strasbourg), in VBB configuration.❍

2 stations maintained by ORSTOM in Africa in VH/LH/MH configuration (VH in m/s/s withcontinuous recording at 0.1sps, LH in m/s/s with continuous recording at 1s ps, MH in m/sand triggered at 5sps).

❍

●

three « contributing » Geoscope stations (in VBB configuration):1 station maintained by ORSTOM and EOST in Vanuatu Islands, PVC.❍

1 station maintained by IPGP (Seismotectonic group) in Chile, ICC.❍

1 station maintained by Centro de Geofisica de Universidad de Lisboa (Portugal), EVO.❍

●

Sixteen stations are remotely accessible (teletransmitted by phone). In case of large events, data fromthese stations are recovered in St Maur (Figure 1, green dots) and made available at the Data Center inParis within one or two days. In parallel to the classical recording in station (VBB configuration), seismicdata are continuously recorded on a magneto-optical disk at 20sps. This method designed by theTechnical Division has been implemented since 1992 in twelve stations (Figure 1, red dots). In allstations the time reference is given by a GPS clock. In the future, a satellite transmission system will beinstalled in ten stations, in cooperation with the french military agency CEA/DASE (see the white dots inFigure 1). In terms of siting locations, the aim of the GEOSCOPE program is almost fulfilled; we plan toinstall only one new station: Vorkouta with our colleagues of IIEPTMG. (Moscow). After the installationof this last station, our goal is to install in each station, a new acquisition chain defined by Agecodagismanufacture (in Toulouse) and DT/IPGP in order to improve their quality.

The GEOSCOPE data center

The GEOSCOPE Data Center has been organized since 1992 around the master piece of the Center, ajuke-box of 300Gbytes. All incoming data are stored on the juke-box after time corrections using

comparisons between reference GPS clock and internal clock time, data quality control anddetermination of the corresponding instrumental responses. All recent earthquakes with magnitudegreater than 6.3, or with smaller magnitude but with particular scientific interest (location, focal depth, ...)are teletransmitted to the Data Center at St Maur, from 17 stations. The corresponding data are madeavailable at the Data Center in Paris for two channels, the VH channel, the MH channel and for twostations (HDC and KIP) the BH channel . All GEOSCOPE existing data from the beginning of thenetwork in 1982 up to now are available from our juke-box. Database is open to external users and dataare easily available through :

Anonymous ftp geoscope.ipgp.jussieu.fr

Mail geoscope@ipgp.jussieu.fr

WWW http://geoscope.ipgp.jussieu.fr

CDROM for data spanning time from 1982 to 1991, are skipping by normal mail way.

GEOSCOPE activities and facilities

The GEOSCOPE station bookOn the WWW server the totality of the GEOSCOPE station-book is provided; it is updated as soonas there is a modification. Each station is described since its beginning with information about theparent organization, the network affiliation, the vault conditions, the site description, theinstrumentation, the sensors, the channels, the dates of upgrade, the sensitivities in the flat part ofthe band-pass of the instrumental responses. You can find the curves of instrumental responsesof the stations, for each component, for each channel, each period of time since the beginning ofthe network.

1.

Continuous VBB (BH) channelsIn parallel to the classical recording in a station (triggered BH channel), seimic data are alsocontinuously recorded on a magneto-optical disk at 20sps. This method, designed by theTechnical Division at Saint Maur in cooperation with the CEA/DASE is now implemented in twelvestations allowing to be sure not to loose some data with the triggering system. The PVC stationlocated in the Pacific Ocean and maintained by our colleagues of EOST in Strasbourg andORSTOM in Nouméa (New Caledonia) also corresponds to a continuous recording of BH channelat 20sps.

2.

The GEOSCOPE noise level plotsThe estimate Power Spectral Density plots have been computed for year 1995. The annualseismic noise level is presented for the 3 channels VH, LH and BH, for the 3 components, Vertical, North-South and East-West. The diurnal and seasonal seismic noise plots are presented for the3 components, and respectively for both channels BH and LH (for the diurnal variation) and for thethree channels BH, LH and VH (for the seasonal variation).

3.

The French SSB station recorded in Quasi real-time dataData are received from the GEOSCOPE SSB station located in France at the Data Center in Parisin quasi real-time. Every hour we get data for three 20 minutes length files, for the MH channel (infact the BH channel decimated at 5sps). The data are immediately and automatically stored on adisk, and the corresponding plots available on the WWW server. The interest is to get immediatelyand continuously data from the french station.

4.

GEOSCOPE CMT determinationA simple inversion method for the fundamental mode Rayleigh wave spectra has made possiblethe rapid determination of the mechanism and the seismic moments. The demonstration is donethat a correct CMT can be retrieved by using few stations, and that in a laterally heterogeneous

5.

Earth.The NetDC procedureThe necessity for dissemination of large datasets to the seismic community leads to the need of anew form of distribution with cooperative environment between the different participating datacenters. The NETDC (Networked Data Centers) idea (designed by IRIS in cooperation with otherData Centers, GEOFON, ORFEUS, UC Berkeley) is to make the access to data transparent tousers, who should not bother about where to ask for data ; the routing of the data request shouldbe solved by the coordinating data centers. The INVENTORY protocol is already working in ourData Center (netdc@ipgp.jussieu.fr) and we will install the Instrumental responses as soon aspossible

6.

The future with GEOSCOPE 2000In the future all GEOSCOPE stations will be equipped with seismometers but also with POSsensors, microthermometers, microbarometers, inclinometers, short period seismometers, GPS.The new acquisition chain designed by DT/IPGP and the manufacturer AGECODAGIS inToulouse (France) will provide recordings from 22 channels, 6 main channels (24bit) for groundvelocity and POS measurements (recorded continuously at 20sps and triggered at 80sps for theSTS2 seismometer), and 16 auxiliary channels in 16bit (1,6s). In the framework of the Test BanTreaty, some GEOSCOPE stations have been chosen to be teletransmitted by satellite inreal-time, and ten stations will be equipped in that purpose with help of CEA/DASE. WUS stationequipment has been installed through a direct cooperation between GEOSCOPE and the SSB(State Seismological Bureau) of Beijing in China. AIS station in the Indian Ocean has beenequipped during 1998 in the framework of the cooperation between IRIS and GEOSCOPE.

7.

Conclusion

The GEOSCOPE data are now worldwide well known, and the number of users and of requests isincreasing with time. Of course the procedure by anonymous ftp is more often used, with a volume of 53Gigabytes instead of 2 Gigabytes through the WWW server for the same period, certainly because ofthe higher rapidity and of easier way in case of multiple requests by the first procedure. GEOSCOPEdata are also available in other Data Centers such as IRIS DMC in Seattle (continuous and event datafrom 1982 to 1996), and the ODC Center (Orfeus) in the Netherlands (event data for European stations).The challenge of the GEOSCOPE Data Center is to offer to the seismic community a performing centraldata archiving system, to get a clear and easy distributed data request processing and to provide newservices management.

page 15Copyright © 1999. Orfeus. All rights reserved.

Observatories and Research Facilities for EUropean SeismologyVolume 1, no 2 April 1999 Orfeus Newsletter

Newsletter joint publication

The Regional Data Center at the Seismological Central ObservatoryGräfenberg SZGRF

Klaus Stammler

Seismological Central Observatory Gräfenberg, Mozartstr. 57, D-91052 Erlangen, Germany. tel: +49 9131 81040-27, fax: +49 9191 81040-99 

Introduction - Stations and instrumentation - Data archive -Access to waveform data - Detections - Locations and bulletins

Introduction

The SZGRF is the data center for data of the Gräfenberg-Array (GRF) and the German RegionalSeismic Network (GRSN). GRF and GRSN are the two major broadband station systems withinGermany. The 13 stations of the GRF array are located within an area of about 50 x 100 km eastof the city of Nuremberg (Fig 1). It became operational in April 1980, although continuousrecordings of the first subarray are available since 1976. The array is operated by theSeismological Central Observatory (SZGRF) which is part of the Federal Institute forGeosciences and Natural Resources (BGR). It is supported by the DeutscheForschungsgemeinschaft (DFG). The GRSN project started in 1991 as a joint research project ofBGR and geophysical institutes of German universities and was funded by the DFG. It wasplanned as an extension of the GRF array. In addition, the GRSN can be regarded as theGerman contribution to international initiatives aimed at the establishment of modern digitalseismic broadband networks on a regional and global scale. The 13 GRSN stations plus 3associated stations are distributed quite evenly over Germany (Fig 1). Digital data of GRF andGRSN are recorded and archived continuously since installation up to now.

Figure 1. Map with station of the GRSN (black traingles) and GRF (green dots)

Stations and Instrumentation

The instrumentation of GRF and GRSN is:GRF:

13 stations GRA1, GRA2, GRA3, GRA4, GRB1, GRB2, GRB3, GRB4, GRB5, GRC1,GRC2, GRC3, GRC4

❍

STS-1 BB-seismometers❍

3 3-component and 10 vertical instruments❍

flat velocity response between 5 Hz and 20 s❍

16-bit gain ranging digitizers (dynamic range 132 dB, resolution 66 dB)❍

●

GRSN:●

16 stations BFO, BRG, BRNL, BSEG, BUG, CLL, CLZ, FUR, GRFO (IRIS/GRSN),GSH, IBBN (assoc.), MOX, RGN (assoc.), STU (assoc.), TNS, WET

❍

15 STS-2 BB seismometers and 1 KS36000 borehole BB instrument (station GRFO)❍

3-component instruments❍

flat velocity response from 40 Hz to 120 s (STS-2) and 5 Hz to 360 s (KS36000)❍

24-bit Quanterra Q860 data loggers❍

Figure 2. Seismometer station of the Gräfenberg array

Figure 3. Seismometer vault of a Gräfenberg station

Data Archive

All data are recorded and archived continuously since installation. The first digital stations of theGRF array were installed in 1976, the array was completed in 1980. The GRSN was started inAugust 1991 with 8 stations and was extended 1993, 1994 and 1996 to the current number ofstations. The data are archived on CD-Recordables, some are on tape (DAT, Exabyte). Most ofthe CD-Recordables are in two 500-CD-Jukeboxes and permit automated access from insideand outside of the SZGRF (Table 1).

Table 1: Available data at the SZGRF

Stream time span continuous Jukebox

GRF 20 HzJul.1976 -Dec.1979

yes not yet

GRF 20 Hz Jan.1980 - now yes yes

GRSN 1 Hz Jan.1992 - now yes yes

GRSN 20 Hz Aug.1991 - now yes yes

GRSN 80 Hz Jan.1997 - now no yes

GRSN 80 Hz Aug.1991 - now yes no

All 20Hz and 1Hz data are continuously on CD and available for automated access (except GRFfrom 1976-1979, currently). The continuous 80 Hz data of the GRSN are mostly on tape, somemore recent on CD, but only a few selected events of local events in Germany are in a jukebox.So data requests on these 80Hz data can be processed only in a few cases.

The data are transmitted to the SZGRF via digital dial-up lines (ISDN) and the GRSN data alsoby tapes. The GRF data are copied several times a day, so the most recent are between 1 and 6hours old. The 20Hz and 1Hz GRSN data are transmitted once at night (European time),transmission gaps on GRSN data are not recovered, so the data may be incomplete. Thecomplete GRSN data set including the 80Hz streams comes after 2-4 weeks on tapes.

Access Methods to Waveform data

The SZGRF runs two automated interfaces for waveform data requests. One is the AutoDRMdeveloped at the Swiss Seismological Service (SSS), the other is a request form on WWW. TheAutoDRM is an e-mail based request manager. It accepts specially formatted e-mails, processesthe requests and sends the data back by e-mail or, preferably for large files, by anonymous ftp.Start with a mail 'please help' or read the manuals at the SSS: The output format of theAutoDRM is always GSE2.0 (cm6-compressed). A mail example for requesting 5 minutes ofGRF z-components is:

BEGINEMAIL [your-email-address]STA_LIST GRFCHAN_LIST BHZ

TIME 1995/08/17 01:08:00.0 TO 1995/08/17 01:13:00.0WAVEFORM GSE2.0STOP

The homepage of the SZGRF allows requests via WWW. It will show a request form for selectionof stations, channel, component, start time, copy length and out put format. Available outputformats are currently SEED, Mini-SEED (data records only), GSE1.0, GSE2.0 and SAC. CSS3.0is in preparation. After submitting the request it is immediately processed and after some time(seconds or minutes depending on the size of the request) a message will tell that a result filehas been prepared and is ready for ftp. With one more mouseclick the transmission byanonymous ftp from the WWW page to the local computer is started. Note that we currently haveonly a digital 64kBit connection to the Internet, please be patient when transmitting larger files.

Of course, we also accept request lists by e-mail. Please send it to Uta Mundl or KlausStammler. Please specify a station list (GRF and/or GRSN or single station names), components(z or zne), channel (BH=20Hz or LH=1Hz), output format (SEED, Mini-SEED, GSE1.0, GSE2.0or SAC) and a time window list. The window list should have one time window per line, the timewindow given by copy start time (format: 23-may-1996_22:45:05 or equivalently23,5,1996,22,45,5 or 1996/5/23,22,45,5) and the number of seconds to copy, separated by oneor more blanks. Do not use blanks within the start time. We also need to know which exchangemedia to use (CD-Recordable, DAT tape, Exabyte tape or ftp).

Automatic Detections

The data of GRF and GRSN are scanned by automatic detection algorithms. The resultinglongperiod and shortperiod detections lists are made available on the Web-Site of the SZGRF.

Preliminary Locations and Bulletins

All detected and recorded local and teleseismic events are manually analyzed on a daily basis.Phase readings, preliminary locations, periods, amplitudes and different magnitudes are storedin a database (INGRES). The homepage of the SZGRF allows requests to this database creatinglistings of various types over a specified time window. Additionally, manually revised local andteleseismic bulletins are available. The are organized as monthly files and are created with atime delay of less than 4 weeks.

page 16Copyright © 1999. Orfeus. All rights reserved.

Observatories and Research Facilities for EUropean SeismologyVolume 1, no 2 April 1999 Orfeus Newsletter

CTBTO: The International Monitoring System

R. C. Stewart

Provisional Technical Secretariat, CTBTO PrepCom, Vienna, Austria

Introduction - The IMS, communications and data integrityIMS seismic stations - IMS and network operators - The PTS at work

The future ( Table 1 (html) - Table 2 (pdf) )

Introduction

The Comprehensive Nuclear-Test Ban Treaty (CTBT) was adopted by the General Assembly ofthe United Nations in September 1996. It prohibits nuclear explosions in the atmosphere,underwater and underground; explosions in outer space are covered by an existing treaty. TheCTBT will enter into force 180 days after ratification by 44 named states. By 1 April 1999, thetreaty had been signed by 152 states and ratified by 33, with 41 signatures and 17 ratificationsfrom the required 44. The states will hold a review meeting in late 1999 to discuss progresstowards entry-into-force.

The signatory states established the Preparatory Commission for the ComprehensiveNuclear-Test-Ban-Treaty Organisation (CTBTO PrepCom) to establish the global verificationsystem required for the CTBT. CTBTO PrepCom is made up of a plenary body of all the statesignatories and a Provisional Technical Secretariat (PTS). The plenary body and its workinggroups meet regularly in Vienna; Working Group B discussing technical issues. The PTS isbased in Vienna and works under the direction of the plenary body. The PTS has a staff ofalmost 200 and an annual budget approaching US$80 million.

The PTS has three main technical tasks. It has to establish the International Monitoring System(IMS), the worldwide network of monitoring stations. It has to set up the International DataCentre (IDC) in Vienna to process the data from these stations and to distribute it, and deriveddata products, to state signatories. Finally, the PTS has to implement a system for on-siteinspections in the event of any suspected violation of the treaty.

The IMS, communications and data integrity

There are a total of 321 stations in the IMS, using four different methods to monitor nuclearexplosions; radionuclide (80 stations), hydroacoustic (11), infrasound (60) and seismic (170).The three "waveform technologies" continuously record data in their respective environments;water pressure in the oceans, atmospheric air pressure and ground motion. In radionuclidemonitoring, the atmosphere is regularly sampled for the presence of nuclear decay products.

Data from all the IMS stations will be transmitted to the IDC in Vienna. The PTS is establishing aGlobal Communications Infrastructure (GCI) based on the Very Small Aperture Terminal (VSAT)satellite communications system. Data flow, and station control, will be over either a direct link toVienna or a link through the host state's National Data Centre (NDC). If the latter, the state canopt to use either the GCI or their own communications links to connect the station and the NDC.The specifications of the GCI are very high, with an up-time of greater than 99.8%.

The CTBTO will provide raw IMS data and IDC data products that will enable states to maketheir own assessment of events. It is vital that the states can be sure of the integrity of this data;that it has not been altered. CTBTO PrepCom intend to ensure this using a combination of dataauthentication, with hardware devices at the stations digitally signing the data, andtamper-detection devices on infrastructure at the stations.

CTBTO data will be available to interested parties through their NDC.

IMS seismic stations

Of the four IMS technologies, seismology is the most mature, with a large number of existingstations in the network. This has the advantage that not all stations will have to be built fromscratch and existing equipment can be upgraded. The disadvantage is that it will result in a veryinhomogenous network.

There are two distinct seismic networks in the IMS, the primary and auxiliary networks, designedby a group of experts convened during the treaty negotiations in Geneva. Both include seismicarrays and 3-component stations. The distribution of stations is shown below and the stationsare listed in Table 1. (There are five stations not included in the figure because their locationshave not yet been decided.)

In order to accommodate the wide range of existing, upgraded and new stations in the networks,the experts specified minimum technical requirements for IMS seismic stations. These are givenin Table 2 (pdf).

The primary seismic network provides even coverage of the Earth's land surface. There is noneed to monitor the oceans or even small islands as explosions in these environments will bedetected by the hydroacoustic network. The primary network includes 30 seismic arrays; mainlyregional arrays with apertures of a few kilometres. These stations will transmit continuous data tothe IDC.

The auxiliary seismic network consists of 120 stations, all 3-component except for 7 seismicarrays. Continuous data will be stored in a local buffer - either at the station or the NDC - for aminimum of 7 days. The IDC will then access this data as it is required.

The auxiliary network has two purposes:

- To provide data to augment that from the primary network to improve location accuracy,particularly depth, and to help identify the source.

- To act as backup to stations in the primary network stations in the event of a problem with aprimary station.

Consequently, the distribution of auxiliary stations is not even, concentrating on areas of highseismicity, including mining seismicity. The design of this network used as many existing seismicstations as possible; there are only 11 new auxiliary stations and one new array, in Israel.However, current estimates are that at least 10 of the stations will need complete replacement ofequipment to fulfill IMS requirements.

IMS and network operators

The majority of the stations in the IMS seismic network already exist, and many of these are partof international networks such as IRIS/IDA, IRIS/USGS, GEOFONE, GEOSCOPE, OHP andMEDNET.

A good relationship between the PTS and the network operators is vital, especially for theauxiliary stations. The network operators were not involved in the negotiations and thereforeview some proposals with scepticism. Some of the issues of concern are:

- Upgrading selected stations in a network will result in an inhomogeneous network which has avariety of implications, including increased costs, for operating the network.

- The addition of GCI and authentication equipment could have a major impact on thehomogeneity of the network. They will also require more power, which could be a problem atremote sites.

- The operational requirements of the IMS network, which are still to be established, will probablybe more strict than existing arrangements, with more frequent calibration and reporting andrequired responses to breakdowns. This will also have cost, and maybe other, implications.

The PTS is committed to cooperating with the network operators to resolve these issues.

The PTS at work

The CTBTO has a mandate, and a budget, to install and operate the IMS networks. The PTS willtherefore pay for any upgrading or new equipment required at primary seismic stations and forthe installation of that equipment. The IMS will also pay for the operation of these stations,although in the case of dual-use stations, where the data is also used for national purposes,these costs are to be shared.

The situation is slightly different for auxiliary seismic stations. The PTS will fund equipment andits installation, upgrading stations to the desired specifications and installing new stations. ThePTS will also bear all the costs associated with the installation of the GCI and authenticationdevices. It was however the intent of the negotiators in Geneva that CTBTO will not payoperational costs for auxiliary stations. This may not be possible and it seems likely that the IMSwill have to bear at least some of the costs of operating the new auxiliary stations.

The PTS is required to be cost effective in all its work, including establishing the IMS. Whereverpossible, work that is contracted out is awarded to the lowest tender. The minimum stationspecifications are very important in establishing Terms of Reference against which bids for workare placed.

For seismic stations, there are a number of distinct stages in the work carried out by the PTS.These are not always done separately and can be combined if convenient.

1. Site Survey

The site survey establishes the requirements for a particular station. For existing,well-established stations this is just a matter of documenting equipment and procedures, a taskwhich can often be carried out by the parent network. Some existing sites have equipment thatfalls well short of the IMS requirements and also need independent noise measurements. Fornew sites the site survey involves a rigorous site selection procedure as well as comprehensivenoise measurements; this can be done by either by the PTS or a contractor, or both together.

2. Station Design

Station design varies greatly in its scope. Upgrades may only need an identification of needs aspart of the site survey. Much more formal design work, including buildings and communicationssystems, may be needed for a new station or an array. It is important that all stations aredesigned to satisfy the minimum specifications, not just exact equipment requirements but alsoto ensure the required data availability; 98% for primary and 90% for auxiliary stations. Thestation therefore has to have adequate provisions for power, security and manning.

3. Equipment Procurement

Equipment procurement is carried out under a strict set of financial rules. Competitive tenderingis the norm, although this is often not appropriate when carrying out an upgrade on existingequipment.

4. Site Preparation and Installation

The preparation and installation of the station can involve a lot of construction work, and the PTS

encourages the use of local contractors. Contracts for installing equipment will also includeproviding training for operators.

5. Testing and Evaluation

Not all stations will require extensive testing and evaluation, particularly the existing ones. Allnew equipment will be tested in situ before certification.

6. Certification

Certification marks the acceptance of a station into the IMS, that the station is providing reliabledata that can be used safely by states. Certification requires full documentation of the stationequipment and procedures. The amount of work required to achieve certification will vary;stations built by the PTS will require much less documentation effort than existing stations.

There is a lot of work to be done in establishing the IMS seismic network. It is expected thatalmost all of the site surveys will be completed by the end of 1999. Design, procurement andinstallation are underway for a growing number of stations, most notably the upgrade of theWarramunga array in Australia and the installation of two new borehole stations in Iran. Theprocess of certification has been started at two stations with more to follow this year.

The future

Current efforts concentrate on establishing the IMS. By the time of entry-into-force however, thefocus should have changed towards running the network in a manner that ensures that timely,authenticated data is available to states. This will require continual checking of the data and theperformance of the stations.

Procedures for the running of the network are being established. The most important documentsare probably the Operational Manuals, being developed by Working Group B, which will set outhow stations have to be operated.

Training of station staff is also very important to ensure good network operations. In 1998, thePTS held its first IMS Technical Training Programme (TTP) for seismic station operators inVienna and at the NORSAR array. A second TTP will be held later this year, with further coursesat regular intervals.

page 17Copyright © 1999. Orfeus. All rights reserved.

Observatories and Research Facilities for EUropean SeismologyVolume 1, no 2 April 1999 Orfeus Newsletter

FDSN WG on data exchange: Meeting December 4, 1998, Seattle, USA

Reporter chairman Bernard Dost

ORFEUS

SEED issues - FDSN archive status - Status AutoDRMNetDC - SPYDER® - VSAT - WILBER - Miscellaneous

SEED issues

A proposal was received to introduce blockette 62 and 49. The purpose being to describe theresponse of a non-linear and non-flat linear device, like a pressure or temperature sensor. Sincethe proposal was new to most of the WG members, it was decided to have a look at it and reportto me back before January 15, 1999 in case there is any problem with the introduction of theseblockettes. No response was received at this date, so the proposal is accepted.

A proposal was tabled for the post archiving of timing corrections, enabling a correction to(mini)SEED data records in a mass storage system. The change requires only the use of onepreviously unused bit in the data header, so the impact is assumed to be minimal. Again, sincethe proposal was coming in at the meeting, members were solicited to give their comments byemail before January 15, 1999. No response was received at this date, so the proposal isaccepted. (link to the email document is pending)

Until now the Network Codes (NCs), which are provided by IRIS, are only using upper casecharacters. There was a concern that network codes could run out and it was proposed to alsoinclude lower case characters. Tim Ahern reported that he would strongly discourage the use ofcase sensitive NCs and he offered to review the concern on the limits on the NCs.

In the conversion from GSE 2.X data to SEED the original instrument response may be definedin the form of frequency-amplitude-phase (FAP) numbers. In SEED poles and zeroes arerequired. The question was raised if SEED could also accept only FAP information. Bernard Doststrongly argued against this, since users will have to make their own adaptation to poles andzeroes if they want to correct for instrument response, initiating a multitude of responses for thesame instrumentation. Also, there is a tendency to process large data volumes in an automaticfashion and the conversion from FAP to poles and zeroes can not easily be automated.

A brief discussion started on additions and/or changes in the SEED format needed to incorporatestrong motion data in SEED. One problem is the channel naming convention and it wasproposed to use an unused letter. No definite conclusion was reached, but the issue is open fordiscussion.

Tim Ahern will check the use of orientation code for electromagnetic recording in SEED. He alsoencourages people to look at the electronic version of the SEED manual, since changes, likeproposed at this meeting, will be available only in the electronic version for quite some time.

FDSN archive status

The USGS/NEIC operates the FDSN event-oriented archive and produces FDSN CD-ROMs.Kay Shedlock noted that volume 5 (first 3 months of 1991) was in press and the rest of the 1991data would be ready in the next few months. The event data, that are retrieved from the FDSNcontinuous archive at the IRIS DMC, are ready until May 1992. Requests from the USGS untilthe end of 1993 are in and will be serviced in 1999.

The continuous FDSN archive is collecting most data routinely, but there are a few importantissues. First of all, MedNet sent its data until November 1995 and has a considerable delay. Itwas not known in detail if data from stations, which do not belong to a major network, do come inregularly and if there are any issues. The Australian data may be a problem, as well as theMexican FDSN stations.ACTION: A list should be compiled of FDSN stations that are having trouble to contribute theirdata in time. (link status report pending)

Tim Ahern prepared a handout concerning FARM volume production by FDSN members. (linkdocument is pending).

It was suggested to start thinking about moving from CD-ROMs to DVDs in the near future. Thegood thing is the increase in data storage. The bad news is the absence of a real standard fordata storage at DVD. In summer 1999 new developments are expected that may bring the use ofthis technology closer.

Status of (auto)DRM installations and usage

This item could best be exploited when there is a fdsn website. Inventories and direct linksshould be set-up and maintained. At Orfeus a list for Europe is presently being maintained.AutoDRM was adapted by Reinoud Sleeman to transfer SEED volumes in March 1999.

NetDC

Rob Casey gave an overview of the philosophy behind NetDC. The status of the software is thatexperiments are being carried out with Berkeley to test the current implementation and to furtherdevelop the code. In March/April 1999 Rob Casey came to Europe to implement the software inParis and de Bilt. The software will be tested in summer 1999. GFZ Potsdam decided not to takepart at this stage, since they lost their programmer.

SPYDER® status and developments

SPYDER® now builds SEED volumes and it has a Y2k problem in using MLINK. Alternatives arebeing looked at and Peter Burkholder at the University of Washington is tackling the problems.

VSAT usage

Satellite transmission is gaining importance in the rapid exchange of waveform data. In Europe alarge network of broad-band stations is being installed in Spain, using VSAT as their mainmeans of data transmission. Could other data centers use these data, when equipped with asatellite dish?

The understanding was that VSAT is a point to point protocol and that multicast is not yetdeveloped. One should keep an open eye on developments in this field.

WILBER distribution

WILBER is installed in April 1999 in Paris and de Bilt.

Miscellaneous

IRIS proposes to set up listservers for the WG's and Tim Ahern is going to arrange a "fdsn.org"name.

Genevieve Roult argued to cut the response plots in the station book at the Nyquist frequency.This was accepted.

The question was raised if the FDSN should consider to use CD-1 or CD-2 as a continuousformat. It was decided that the format should be evaluated and comments discussed in the nextWG meeting.

page 18Copyright © 1999. Orfeus. All rights reserved.

Observatories and Research Facilities for EUropean SeismologyVolume 1, no 2 April 1999 Orfeus Newsletter

Announcements

ORFEUS meetings at the IUGG99 in Birmingham, 18-30 July 1999

All meetings are informal and discussion is encouraged

Saturday July 24, late afternoon/evening: Joint FDSN WG1 and ORFEUS WG1 meeting.Station siting, ORFEUS part will be Europe and Mediterranean AreaYou are invited to prepare a short (5 min) presentation on new networks in your country.

Sunday July 25, late afternoon/evening: Joint FDSN WG3 and ORFEUS WG4 meeting.Seismological software, ORFEUS part will be discussions on how to improve the ORFEUSSeismological Software Library.Among others presentation of recent developments within the FISSURES project at IRISDMC and discussions about Java in seismology.

Tuesday July 27, 18:00 - 20:00 ORFEUS workmeetingPreliminary title: Data exchange in the next centuryInformal discussion on the future of data archiving, data access and exchange within theEuropean-Mediterranean area.

Wednesday July 28, 17:30 - 19:30: joint FDSN WG2 and ORFEUS WG2 meeting.InstrumentationPresentations and discussions on calibration standards and new instrumentation.

●

ORFEUS Wilber with Java Seismogram Viewer

With the aim to obtain a certain conformity in user data access Deborah Barnes andRobert Casey, both from IRIS DMC, installed an ORFEUS Wilber version that presentlyruns on our Spyder® data.

Further with the help of Anthony Lomax, from Geosciences Azur in Nice, ORFEUS alsoinstalled Anthony's Java Seismogram Viewer within ORFEUS Wilber to enable a user toinspect individual signals. This is presently an experimental version that may not work onolder browser versions.

Please, let us (Läslo Evers) know if you have comments or meet problems in eitherORFEUS Wilber or the Java Seismogram Viewer so we can improve.

The usual ORFEUS web requests will be still operating.

●

Educational oriented seismology links: Seismo-edu

Seismo-edu consists of links to Electronically available lecture notes, amateur seismology,popular seismology etc. Presently, this is under development, however, suggestions areappreciated.

●

page 19Copyright © 1999. Orfeus. All rights reserved.