Forecasting Seismicity on Local to Regional Scal

Gerstenberger, M.

Werner, M. J.

Wiemer, S.

Woessner, J.

Earth-prints Repository

Forecasting seismicity on
local and regional scales
J. Woessner, S. Wiemer
M. C. Gerstenberger 
M. Werner
ETH Zurich, Swiss Seismological Service
GNS Science
UCLA
5th International Workshop on Statistical Seismology:
Physical and Stochastic Modelling of Earthquake Occurrence and Forecasting
Outline
1. Seismic eArly Warning For EuRope 
(SAFER): Local scale time-dependent  
seismic hazard and earthquake forecasting
2. A comparative retrospective forecast test 
for the Landers 1992 earthquake
3. Short Term Earthquake Probabilities: 
STEP in Europe - Examples from 
Switzerland and Turkey
SAFER-Objectives
1. Improve understanding of spatial  and 
temporal evolution of clustered seismicity 
(SAFER, NERIES)
2. Improve links to underlying physics of 
earthquakes (SAFER, NERIES)
3. Develop testable forecast models (NERIES, 
CSEP)
4. Validate forecast models using community 
accepted testing procedures (CSEP)
Project: Target scale
Local scale
NERIES
JRA2
Time-dependent hazard for e.g.
aftershock sequences, swarms 
Time-dependent hazard on 
nationwide / European scale
SAFER
WP5
CSEP
Earthquake
 predictability
From Local to 
Global scales
Regional scale
The Landers Retro-Test
● Methodological developments in a region of
– high seismicity
– high data quality and various available earthquake 
catalogs
– main shock with multiple slip distribution solutions
– additional data: GPS, INSAR, fault model 
● Comparative forecast tests on local scale and 
short periods
● Development of an suitable testing strategy 
combining different model elements 
The Landers Retro-Test
● Forecast region: -117.5W/33.25N - -115.5W
/35.5N
● Data selection region: -119W/32.5N - -115.5W
/36.5N
● Grid: 0.05º X 0.05º
● Relocated Hauksson catalog (1984-2001)
● Background model: Declustered catalog 1984-
1991 using modified Reasenberg declustering 
code (see Helmstetter, 2007)
● Forecasts: 24h forecasts, starting 28.06.1992 
for 90 days, 4≤M≤8
Background model
Background model
Southern California Forecast box
Background Hazard
Southern California Forecast box
Forecast Models
● Short Term Earthquake Probabilitites 
(STEP, Gerstenberger et al., 2005) 
● STEP generic element with Coulomb 
weighting
● Epidemic Type Aftershock Sequence 
(ETAS) model (Helmstetter et al., 2007)
Focus: Comparative Test
STEP: Model elements
Gerstenberger et al., 2005
Model elements:
Generic
Sequence specific
Spatially heterogeneous
Coulomb: Model and Scalar
Coulomb stress changes Converted scalar
Courtesy of Toda et al., 1998
Forecast: Day 3 (30-31.6.1992)
STEP generic STEP generic element 
Coulomb scaled
Forecast: Day 3 (30-31.6.1992)
STEP generic element 
Coulomb scaled
ETAS
RELM-Tests
● L-Test: Data consistency test in likelihood space
● N-Test: Data consistency test in number space 
● R-Test: Likelihood ratio test for relative 
performance of forecast models:
– Use forecast of one model as Null-hypothesis, 
forecast of second model as Test-hypothesis
R-Test: Time series
R-Test: Time series
R-Test: Time series
Retrospective Testing Summary
● R-Test supports ETAS as superior model of the 
evaluated ones
● STEP model capabilities not fully explored
● Including more models:
Coulomb in combination with rate- and state 
friction model needs to be tested against (INGV)
● Forecasting scheme with memory: work in 
progress
STEP - Switzerland
Needed or not? Sure!
● Destructive historical 
earthquakes (1356 
Basel, Mw=6.9)
● Geothermal injection 
experiment in Basel in 
2006
Researchers cause earthquake in Basel
Observed vs. instrumental intensities
ML=3.4, 
Basel, 
08.12.2006
STEP - Switzerland
Background
Challenges:
- low-seismicity region: low 
aftershock productivity 
region?
- are there other models more 
appropriate for this region?
Based on Swiss Seismic 
Hazard 2004 
(Giardini et al., 2004) 
STEP - Switzerland
● Stable real-time implementation
● Regionalization of seismicity parameters: new 
methodologies needed for low-seismicity region
● Improvement of attenuation function
● STEP on a very local scale: probability 
forecast for induced seismicity
Summary
STEP – Switzerland: Today
● Stable real-time implementation
● Regionalization of seismicity parameters: new 
methodologies needed for low-seismicity region
● Improvement of attenuation function
● STEP on a very local scale: probability 
forecast for induced seismicity
Summary
Work In Progress
STEP in Turkey - Studying the North Anatolian Fault System:
Properties of the aftershock Sequence of the 1999 Mw 7.4 Kocaeli 
Earthquake: Implication for Aftershock Hazard
M.B. Demircioglu, S. Wiemer, J. Woessner,
K. Sesetyan, M. Erdik


Forecasting Seismicity on Local to Regional Scale

http://www.earth-prints.org/bitstream/2122/2317/1/Woessner_20070601.pdf

Forecasting Seismicity on Local to Regional Scale

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