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Seismic Hazard Model for the Middle-East Region,
Citation preview
Seismic Hazard Model
For Middle-East Region
Laurentiu Danciu
Swiss Seismological Service,
ETH Zurich, Switzerland &
GEM Hazard Modeler
Karin Sesetyan
Mine Demircioglu
KANDILLI OBSERVATORY
and EARTHQUAKE RESEARCH
INSTITUTE,
Istanbul Turkey
EMME Final Meeting
September 30th – October 2nd
Istanbul, Turkey
Regional PSHA Model• Regional seismic hazard assessment
Regional PSHA Model• Harmonization across national-borders
Target
Stability
1. Provide assurance that the numerical hazard results will be stable for the next years (50 years ?)
2. Unless significant new seismic information, which could occur at any time, calls for a major revision
Consensus
What Consensus stands for?
• 1) there is not likely to be "consensus" (as the word is commonly understood) among the various experts and
• 2) no single interpretation concerning a complex earth - sciences issue is the "correct" one.
SSHAC : Recommendations for PSHA: Guidance on Uncertainty and Use
of Experts
Most likely for no consensus there is a consensus!
SHARE Project- DB Stats
• 3 source models• 960 End-Branches• 12 Intensity Measure Types• 7 Return Periods [50 to 10000Years]• Mean, Median and Four Quantile• 130 000 sites
‣ Hazard Maps: 504
‣ Hazard Curves: 9.36 mil
‣ Uniform Hazard Spectra: 5.46mil
‣ Disaggregation: ongoing
Dynamic ModelEMME Project- DB Stats
55
00
0
sites
Overview
• Earthquake Catalog
• Maximum Magnitude
• Seismic Source Models
– Area Source Model
– Fault source Model
– Spatially Smoothed Seismicity
EMME Earthquake Catalog• Historical part (-1900)
• Early and modern instrumental (~2006)
• Harmonized in terms of Mw
Total : 27174 events
EMME Earthquake Catalog
• Seismicity models require a – Declustered earthquake catalog of independent events
– Completeness intervals for estimating the Poissonian (time-independent) earthquake rates.
• Declustering Method. – Windowing approach based on windows provided by Grünt
hal (1985)• Gardner and Knopoff (1974)
– After Declustering: 10524 events
Declustered Earthquake Catalog
– After Declustering: 10524 events
EMME Earthquake Catalog• 18 Completeness super-zones
Completeness plots per super-zones
Completeness plots per super-zones
Completeness plots per super-zones
Maximum Magnitude
• Largest magnitudes that a seismogenic region iscapable of generating.
• Upper-bound magnitude to the earthquakerecurrence (frequency-magnitude) curve.
• Maximum Magnitude assessment (Super-Zones)– Historical seismicity record
– Location uncertainties
– Analogies to tectonic regions
– Added increment (0.30)
Maximum Magnitude
Weighted Mmax
Maximum Magnitude: Sensitivity
Maximum Magnitude: Sensitivity
5%
13%
18%
Yerevan City
Magnitude - DisaggregationMaximum Magnitude = 8.00
aGR = 4.00
bGR = 1.00
Maximum Magnitude: Sensitivity
• Maximum magnitude impacts the activity
computation –if used to anchor the expert
fitting
• 5 to 20% increased hazard values
• Return period dependent
• The pair of Maximum Magnitude
Recurrence rates to carefully be revised
Source Model Logic Tree
Area Source Model
• Classical area source zones based on the tectonic findings and their correlation and up-to-day seismicity
• Derived from seismicity patterns
– Ensure the zonation adequately reflect this pattern
• Surface projection of identified active faults (capable of generating earthquakes)
Model Construction: Phase One
• Country based models
• Phase one:– Overlapping sources at national borders
• [ trying to keep the original information]
– Remove duplicates (the same source defined within countries)
– Eliminate zones too small to be analyzed (spatially smooth seismicity take cares of it)
Model Construction: Phase Two
– Simplify unnecessary or artificial complex zonation
– Reshaping according to the known main seismogenic features (i.e known faults )
– Local experts feedback
– Reconcile different interpretations
– New sources re-defined after technical discussions among the national representatives/local experts
Area Source Model• 143 shallow crustal area source zones,
• 6 for modeling the deep seismicity, and
• 5 complex faults
Source Characterization
• Main Assumptions:
– Homogeneous, declustered catalogue
– Completeness defined for 18 super zones spanning the entire region
– Maximum likelihood approach (Weichert 1984)
– Truncated Guttenberg-Richter Magnitude Frequency Distribution
• 10a – annual number of events of magnitude greater or equal to zero
• b-value
• Truncated at each assigned maximum magnitude
• For each source three magnitude-frequency-distributions were derived
• A Matlab* toolbox was developed
Source Characterization: issues
• Sources with limited number of events
• Sources with less that 15 events were assigned with a default activity rate corresponding to each region
• 30 area source zones with less than 15 events
• Estimation stability achieved for more than 30 events/source
Source Characterization: issues
• Light color shows area sources with less than 15 events
Source Characterization: issues• Automated procedure was constantly under predicting the
occurrence rates of moderate to large magnitudes
Source Characterization: issues• Automated procedure was constantly under predicting the
occurrence rates of moderate to large magnitudes
Source Characterization: issues• Automated procedure was constantly under predicting the
occurrence rates of moderate to large magnitudes
Source Characterization: solution• Expert fitting/adjustments
automated
Source Characterization: solution• Expert fitting/adjustments
automated
bGR-value : Spatial Distribution
bGR-value is between 0.70 to 0.75
bGR-value is between 1.05 to 1.25
Sanity Check: aGR normalized:
• Yellow color shows area sources with very low annual activity per km2
Sanity Check: Seismic Moment
log(Mo) c dMw
c 16.05
d 1.5
Kanamori and Anderson (1975)
Sanity Check: Global Strain Rate
Courtesy of C.Kreemer
Area Sources vs Global Strain Rate
Seismic Moment vs.Global Strain Rate
Source Parameterization
• Depth Distribution (three values and the corresponding weights):
– Active shallow crust
– Nested Deep Seismicity
– Subduction Inslab
• Focal Mechanisms
– Rake Angle values (Aki’s definition)
– Percentage weights
• Ruptures Orientation
– Strike Angle (Azimuth)
– Dip Angle
• Rupture Properties
– Upper and Lower Seismogenic Depth
Complex Fault
Area Source [Single Rupture]
Depth Distribution
Dip-Angle Distribution
• Yellow color shows area sources with
• dip angles smaller than 30o
Source Model Logic Tree
EMME Faults Dataset• Fault source model derived from the faults database collected within WP02
– Total number: 3397 fault segments
– Total Km: 91551km
Fault Sources
• Criteria to select active faults to be used for hazard assessment:– Identified active faults [capable of earthquakes]: Northern
Anatolian Faults, Marmara Faults, Zagros Transform Faults
– At least 0.10mm/year (1m in 1000years - Neocene)
– Maximum magnitude equal to 6.20
– Fully parameterized:• Geometry
• Slip-rates
– Confidence Classes:• Class A: complete information provided by the compiler
• Class B: partial information provided by compiler
• Class C: limited information provided
• Class D: only top trace available
Fault Sources
• Confidence Classes:• Class A (red): complete information provided by the compiler
• Class B (green): partial information provided by compiler
• Class C (blue): limited information provided
Fault Sources-SHARE projects• Class A complete information provided by the compiler
Fault Sources- EMME• Class B partial information provided by the compiler
Fault Sources- EMME
?
Fault Sources- Class C• Class C fault trace and fault type info available
• Maximum magnitude – Estimated from faults size
– Slip rate
• First Slip Rate Estimated as proposed by USGS
• First Slip Rate Estimated as proposed by USGS
15.1
8.5
15.0
<31
5.0
9.2
16.8
11.4
16.86
.8
13.2
9.9
13
13
4
11±5
10±2
6±13±2
25±5
~4
20.0
05
10
15
20
5
5
15
20
Fault Sources- Class C -refinement
By Prof. Asif Khan
Active Faults
Active FaultsHow to characterize the seismic potential of the faults?- Convert slip-rates to seismicity
Fault Source Model Characterization
Procedure:1. Generate a buffer region of 20km
for each fault
Procedure:2. Remove earthquakes within buffer zone
3. Activity on faults computed from slip rates4. Activity on the background – based on the “outside” catalogue
Fault Source Model Characterization
Faults + Background Seismicity
Faults + Removed Earthquakes
3202 earthquakes removedMagnitude range: 4.00 to 7.90
Faults CharacterizationActivity rates are calculated from geologic information:
•Slip rate •Fault length / aspect ratio•Maximum Magnitude
Recurrence Rate Model:•Anderson & Luco (1983) Model 2:
•b-value assumed from the corresponding completeness super zones•Integration from Mmin = 5.00 to Faults Mmax
N2(M ) =d - b
b
æ
èçö
ø÷S
b
æ
èçö
ø÷eb-(Mmax-M -1éë
ùûe-((d /2)Mmax )
Activity Rates - Background
• Smoothed spatially with a variable Kernel
– r : epicentral distance
– di: Variable epicentral distance to next neighbor
nv
• Optimization for distance parameter with
retrospective tests
vsF (r,di ) c(di )(r2d
i
2 )1.5
Kernel Optimization: Retrospective Testing
Optimize kernel using a likelihood tests Split catalog in learning
and target period
Optimize on 5 year target period
Use best likelihood-value to generate model rates
Learning Period Target Period
1000 2002 2007
Activity Comparison
Fault Source Model
Combine seismicity from long term geological observations with observed seismicity
Fault Source Model
Source Parameterization
• Depth Distribution
• Focal Mechanisms
– Rake Angle values (Aki’s definition)
– Percentage weights
• Ruptures Orientation: Strike and Dip Angles
• Rupture Properties
– Upper and Lower Seismogenic Depth
Point Source [Single Rupture]
Simple Fault• Fault Top Trace
• Focal Mechanisms
– Rake Angle values (Aki’s definition)
• Ruptures Orientation: Strike and Dip Angles
• Rupture Properties
– Upper and Lower Seismogenic Depth
24th Sept 2013 Event in Pakistan
15Years Seismicity Mw >= 6.5
2013-09-24 Awaran Pakistan
2013-04-16 East of Khash Iran
2011-10-23 Eastern Turkey
2011-01-18 southwestern Pakistan
2010-12-20 southeastern Iran
2009-01-03 Hindu Kush region Afghanistan
2008-10-05 Kyrgyzstan
2005-12-12 Hindu Kush region Afghanistan
2005-10-08 Pakistan
2004-04-05 Hindu Kush region Afghanistan
2003-12-26 Southeastern Iran
2002-06-22 Western Iran
2002-03-03 Hindu Kush region Afghanistan
2002-02-03 western Turkey
2001-01-26 Gujarat India
2000-12-06 Turkmenistan
2000-11-25 Caspian Sea offshore Azerbaijan
1999-11-12 western Turkey
1999-11-08 Hindu Kush region Afghanistan
1999-08-17 Western Turkey
1999-03-04 Southern Iran
1998-05-30 Hindu Kush region Afghanistan
1998-03-14 Eastern Iran
Before 24th Sept 2013 Event in Pakistan
EMME Results, before the earthquake
Source Model Logic Tree
Spatially Smoothed Seismicity
• Based on the – Up-to-date seismicity
– Declustered catalogue
• Main Assumption:– Earthquake's self-similarity: earthquakes occur at near clusters of
previous smaller earthquakes.
– Derived equally spaced [10 x 10 km] cells
– 53300 non-overlapping cells
– the earthquake rates determined for cells are spatially smoothed using a one Gaussian smoothing kernel Frankel 1995]
– Kernel constant size equals to 25km
Smoothing Algorithms
Source Parameterization
• Depth Distribution (three values and the corresponding weights):
• Focal Mechanisms
– Rake Angle values (Aki’s definition)
– Percentage weights
• Ruptures Orientation
– Strike Angle (Azimuth)
– Dip Angle
• Rupture Properties
– Upper and Lower Seismogenic Depth
Point Source [Single Rupture]
Source Model Logic Tree
How do we weight them?
Summary•Building a regional seismic hazard model is a collective effort•Aim at generating the up-to-date , flexible and scalable database hat will permit continuous update, refinement, and analysis.
•Data will be parameterized and input into the database with a specific format.
Hazard
Software
“Black Box”
INPUT OUTPUT
“Easy Review” Box
Data
Interpretations
Assumptions
Summary•Transparent computational procedure, with all input files available as well as the software packages (Hazard Modeler Toolkit, OpenQuake)•Each dataset has certain degree of completeness, but there is room for improvements;•Specifically,
•The depth information of the events•Maximum magnitude definition•More parameterized faults•Velocities from GPS data
•Revision of all source models•What are the weakness points of each model?
•Road map to the final deliverable
Thank you!