Annual Meeting - SCEC.org

Poster Abstracts
Comparison of this new event history on the Claremont fault with the Hog Lake site along the Clark segment of central San
Jacinto fault shows some overlaps in event ages from 3 events. The strongest correlation is between Event 3 at Mystic Lake and
Event 2 at Hog Lake, both of which are constrained to within 100 years. This may be evidence that some events can jump the
San Jacinto Valley releasing step-over, or that events on one fault can trigger closely timed events on the other fault.
Comparison of the Mystic Lake data with event histories from sites along the San Andreas fault north and south of its juncture
with the northern San Jacinto fault show that some events north of the juncture overlap better with events at Mystic Lake than
with events at sites on the San Andreas fault to the south of the juncture (Events 5 and 6). This leaves open the possibility that
ruptures may have jumped from the San Andreas fault to the San Jacinto fault (or vice versa) in the past.
NEAR-FIELD COSEISMIC DEFORMATION QUANTIFIED FROM DIFFERENTIAL AIRBORNE LIDAR OF
THE EL MAYOR-CUCAPAH EARTHQUAKE SURFACE RUPTURE (A-120)
M.E. Oskin, J.R. Arrowsmith, A. Hinojosa, A.J. Elliott, O. Teran, J.M. Fletcher, S. Saripali, and D. Banesh
We analyze a high-resolution (9 to 18 returns/sq. m) airborne LiDAR topographic survey of the 4 April 2010 M7.2 El Mayor-
Cucapah surface rupture to quantify fault slip and the amount and style of distributed near-field deformation. This is the first
LiDAR survey to capture a fresh rupture in a sparsely vegetated region with pre-earthquake lower-resolution (5m-pixel)
LiDAR data. The amount of distributed deformation we observe suggests the frequency of large earthquakes on secondary
fault arrays may often be underestimated from geologic observations of prehistoric fault slip.The earthquake produced a 120
km-long, complex multi-segment rupture with dextral-normal slip through northernmost Baja California, Mexico. The postevent
survey reveals numerous surface ruptures, including subtle distributed slip above previously undocumented faults
within the Colorado River delta. Differential elevations from comparison of pre- and post-event topography quantify
distributed deformation surrounding fault ruptures in the Sierra Cucapah. Folding strains up to 1000 microstrains occur in the
absence of visible faulting. Shear with opposite sense to adjacent faulting demonstrates that these strains were, at least initially,
elastic. Changes in shallow stress that accompanied this strain may be comparable to the coseismic stress drop at seismogenic
depth. We speculate that distributed mechanisms, such as granular deformation and velocity strengthening creep on small
faults, relaxed these stresses post-seismically and rendered this shallow, distributed deformation into permanent fault-related
folding.
IMAGING COSEISMIC SURFACE DEFORMATION AND DAMAGE USING SAR AND GPS: RESULTS FROM
ARIA-EQ FROM 2011 M9.0 TOHOKU-OKI AND M6.3 CHRISTCHURCH EARTHQUAKES (A-042)
S.E. Owen, S.H. Yun, A. Moore, E. Fielding, P. Agram, F. Webb, M. Simons, P. Rosen, J. Cruz, and H. Hua
The Advanced Rapid Imaging and Analysis for Earthquakes (ARIA-EQ) project is a joint JPL/Caltech effort to automate
geodetic imaging capabilities for hazard response. Geodetic imaging’s unique ability to capture the surface deformation in
high spatial and temporal resolution allow us to resolve the earthquake fault geometry and fault slip in correspondingly high
spatial & temporal detail. In addition, remote sensing with radar provides change detection and damage assessment
capabilities that can image even at night or through clouds. However, since these data sets are still essentially hand-crafted,
they are not generated rapidly and reliably enough to be useful for informing decision-making agencies and the public
following an earthquake. We are building an end-to-end prototype geodetic imaging data system that would integrate InSAR,
GPS, seismology, and modeling to deliver actionable science and situational awareness products.
We will present our recent results generating products for 2011 M9.0 Tohoku-oki and M6.3 Christchurch earthquakes. In
response to the Tohoku-oki event, we have processed GPS data supplied by Japan’s Geospatial Information Authority to
generate measurements of coseismic and postseismic deformation. These coseismic results enabled several research groups to
better constrain models of the earthquake shortly after the event, helping to understand where this unexpectedly large
earthquake had occurred along a well-studied subduction zone fault. We processed radar data from several SAR platforms
and mosaicked interferograms show spectacular coseismic and aftershock deformation.
We have also developed a prototype algorithm to detect surface property change caused by natural or man-made damage
using InSAR coherence change. The algorithm was tested on construction sites in Pasadena, California. The developed
algorithm performed significantly better, producing 150 % higher signal-to-noise ratio, than a standard coherence change
detection method. We applied the algorithm to 2011 M6.3 Christchurch earthquake in New Zealand using ALOS PALSAR
data. In Christchurch area we detected three different types of damage: liquefaction, building collapse, and landslide. These
detected damage sites were confirmed with Google earth images provided by GeoEye. Larger‐scale damage pattern also
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