Seismology Response to the 2010 M7.2 El Mayor- Cucapah Earthquake
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Transcript of Seismology Response to the 2010 M7.2 El Mayor- Cucapah Earthquake
Seismology Response to the 2010 M7.2 El Mayor-Cucapah
Earthquake
Elizabeth Cochran11 Sept. 2011
Overview
1. Deployment• Instruments and people
2. Aftershock Relocation• Clouds to faults?
3. Lessons for the Next Response?• Objectives, Communication, Instrumentation, Sites
4 April 2010 M7.2 El Mayor-Cucapahaka ‘Baja Earthquake’
• Most of the rupture was south of the California-Mexico border
• Deployment Considerations:• Coordination between
US and Mexican researchers
• Customs issues for instrumentation
Seismic Deployment
• Deployment teams: UCR, UCSB and SDSU
• Instrumentation:• 5 UCR and 3 UCSB
station set-ups• Installed strong
(EpiSensors) and weak motion (L4) sensors
Early Aftershocks: April 4 – 6
Many thanks to the field teams!
Safety First!
Seismic Deployment:Stations installed between 4 April and 14 June 2010
Zoom Area
Aftershock Relocation:
Study Area
• 4000+ events within the study area
• 13 stations:• 8 temporary (5 UCR; 3
UCSB)• 5 SCSN
• Manually picked P and S arrivals
• And, cross-correlated for higher precision
SCSN Catalog Locations
K. Kroll, Masters Thesis, UCR
Relocation:Methods
HypoDD
• Uses automated, manual, and cross-correlation picks
• Provides good relative locations for well-clustered events
• Relative locations are not highly dependent on velocity model
Velocity Models UsedCVM-4 Imperial Valley,
10% higher, 10%, & 20% lower
Collapsing Method
• Defines clusters of events
• Principle component analysis of cluster to determine if is a point, line, or plane
• Moves the events within error estimates
Relocation:HypoDD Results
• HypoDD relocations suggest some NW and NE striking features
• However, features are still not very clear
Relocation:Collapsing Results
• NW and NE striking features are better defined
• Features that are consistent across the models are labeled
Zoom Area
See Poster B-46 for more results!
Aftershock Relocation in the Yuha Desert Following the 4 April 2010 M7.2 El Mayor-Cucapah Earthquake By K.A. Kroll, E.S. Cochran and K.B. Richards-Dinger
Lessons for the Next Response
Successful response requires:1. Known science objectives
2010
US-side covered a limited portion of the aftershock zone, no simple surface rupture, edge of the SCSN.
Goal: Use relocated seismicity to better define structures in the region
Future
High-resolution studies of large aftershocks?
Fault zone studies?
Site response across an urban area?
Not clear if it is possible to fully define objectives in advance?
Lessons for the Next Response
Successful response requires: Known science objectives
2. Rapid communication between groups interested in deployment
Successful coordination through the SCEC Response Wiki
Ensure information is relayed to all potential volunteers (not just PIs)
Communication between groups during a large event (satellite phones, text message)?
Lessons for the Next Response
Successful response requires: Known science objectives Rapid communication between groups interested in
deployment
3. Available equipment and locations2010
Only a few stations were needed; telemetry was not reliable
Future
More equipment needed for a large quake; SCEC RAMP equipment needs modernizing
Real time data integration into the network; important for rapid event detection, aftershock forecasting, research
Often difficult to find adequate locations (security, power, etc.)
Lessons for the Next Response
Successful response requires: Known science objectives Rapid communication between groups interested in
deployment× Available equipment, including telemetry
• Urban Ramp• Clear view of sky for GPS
timing is often an issue• Small footprint makes
building/land owners more comfortable
• Smaller AC Power supply with charge controller and small battery
• Coupling sensor to Earth for ground response observations
• SSI – Free Field or building response
• Remote Ramp• Secure location• Low power, autonomous,
with ability to telemeter state of health at a minimum
• Often marginal or no land-based communications service
• Costly to maintain if the sites have to be visited regularly
• Costly to integrate the data into the regional network after the fact.
RAMP Needs
From Steidl, Seismic Instrumentation Workshop
The End