Annual Meeting - SCEC.org

Poster Abstracts
Fault is segmented. An important “unanticipated” phenomenon in relation to the Mw 9.0 earthquake in Japan was that five
segments along the subduction zone ruptured together, rather than independently as scientists had earlier predicted. What are
the expected consequences of the assumptions regarding segmentation versus nonsegmentation of the Shoreline Fault when
estimating earthquake potential?” Unfortunately, presenters were unable provide clear answers on situation related to the
assumptions.
The emergency in Japan (March 2011) provides as an important wake-up call for contribution. Tools and knowledge for the
proper Seismic Hazard Analysis(SHA) nuclear plants located in California exist, and we cannot afford to ignore new
information. During the last 6 months have spent our own money, time and effort we achieved preliminary results about
assumptions regarding segmentation versus non-segmentation of the Shoreline Fault zone(SFZ) and San Luis Bay Fault
Zone(SLBFZ) when estimating earthquake potential for DCNPP.
Effect of SFZ and SLBFZ segmentations on simulation of long-period seismic motions (LPSM) and seismic load will be
presented for DCNPP. As a result of the our analysis it is possible to conclude, that for the DCNPP site the segmentations of
SFZ and SLBFZ introduce additional extremes for LPSM and effects of vibratory ground motion should be properly estimated
in SHA and included in design of seismic load for DCPP. LPSM with multiple oscillations can cause severe nonlinear
structural response and have become a crucial consideration in proper SHA of DCNPP due to cyclic load. The nature of such
cyclic loading induces progressive alteration in the bearing capacity and head displacement of the foundation. This may lead
to disastrous consequences (for example Japan- 2011 lessons). These findings should be investigated more accurately for
proper SHA of DCNPP. We have very strong concerns about seismic issues at DCNPP and proper estimate of ground motions
based on existing assumptions and approaches.
BROADBAND CYBERSHAKE PLATFORM: SEISMOGRAM SYNTHESIS FOR BROADBAND PHYSICS-
BASED PROBABILISTIC SEISMIC HAZARD ANALYSIS (A-038)
S. Callaghan, P. Maechling, P. Small, K. Milner, R. Graves, T.H. Jordan, and the CyberShake Collaboration
Researchers at the Southern California Earthquake Center (SCEC) have developed the CyberShake computational platform to
perform probabilistic seismic hazard analysis (PSHA) in the Los Angeles region (Graves et al., 2010) using deterministic wave
propagation simulations at frequencies up to 0.5 Hz. CyberShake uses seismic reciprocity to calculate synthetic seismograms
for a suite of more than 600,000 rupture realizations. From this set of seismograms we compute intensity measures, which are
then combined into a PSHA hazard curve for the site of interest.
Here we report on expanded CyberShake capabilities. We have integrated the high-frequency computational capabilities of
the SCEC Broadband Platform into CyberShake, producing the Broadband CyberShake Platform. The Broadband CyberShake
Platform extends the frequency range up to 10 Hz by combining low frequency deterministic synthetic seismograms with
higher frequency stochastic seismograms. We can now calculate physics-based seismograms and PSHA hazard curves for
intensity measures such as PGA that are strongly dependent on higher frequency ground motions.
We are applying our new broadband computational capabilities of the Broadband CyberShake Platform at southern California
sites selected to support validation of this newly developed PSHA computational technique. This includes calculation of
Broadband CyberShake seismograms and hazard curves at precariously balanced rock sites to validate our technique and to
investigate the impact of higher frequencies on these fragile geological structures.
We have also added functionality to calculate CyberShake seismograms using CVM-H v11.2 as well as CVM-S4. This enables
us to compare seismograms and hazard curves generated with the two velocity models and determine the impact the choice of
velocity model has on the predicted hazard. We have calculated seismograms and PSHA curves for southern California sites
selected to improve our understanding of the contribution velocity model has on seismic hazard.
TRIGGERED NON-VOLCANIC TREMOR FOLLOWING THE 2011 TOHOKU-OKI EARTHQUAKE (A-104)
K. Chao, Z. Peng, D.P. Hill, D.R. Shelly, B. Enescu, B. Fry, and C. Aiken
Non-volcanic tremor triggered by teleseismic surface waves was recently discovered in many different types of tectonic
boundaries, mainly around major subduction zones around the Pacific Rim and the San Andreas Fault system in California.
Here we present the observations of tremor around the world triggered by the 2011 Mw9.0 Tohoku-Oki, Japan earthquake.
We identified clear tremor signals recorded at many stations at Parkfield of the San Andreas Fault in central California. The
tremor begins around the ~100-sec period S-wave arrival with a minor burst coinciding with the SH-SH arrival as recorded on
the nearby broadband station PKD. A more pronounced burst coincides with the Love arrival followed by a spike in tremor
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