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Variations in Ground Motion Amplification in the Los Angeles Basin due to the 2019 M7.1 Ridgecrest Earthquake: Implications for the Long-Period Response of Infrastructure

Kohler, Monica D. and Filippitzis, Filippos and Graves, Robert and Massari, Anthony and Heaton, Thomas and Clayton, Robert and Bunn, Julian and Guy, Richard and Chandy, K. Mani (2021) Variations in Ground Motion Amplification in the Los Angeles Basin due to the 2019 M7.1 Ridgecrest Earthquake: Implications for the Long-Period Response of Infrastructure. In: ASCE-UCLA Lifelines Conference 2021-2022, 31 January-11 February 2022, Virtual. (Submitted)

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Coherent patterns and large variations in ground shaking amplification were observed in the Los Angeles basin during the 2019 M7.1 Ridgecrest earthquake. In particular, 3 s to 6 s responses showed variations due to shallow basin geological structure that have implications for the response to large earthquakes of mid-rises, high-rises, long-span bridges, and fuel storage tanks, even if epicentral distances are several hundred kilometers. The Ridgecrest strong-motion data were recorded by seismic stations from the spatially dense Community Seismic Network, the Southern California Seismic Network, and the California Strong Motion Instrumentation Program. The mainshock observations are compared at the same locations with ground motion simulations to examine the regions that experienced the largest shaking, and to investigate the geological sources of large-amplitude shaking. The simulations were computed for the two most commonly-used regional community seismic velocity models, CVM-S4.26.M01 (‘CVM-S’) and CVM-H 15.1.0 (‘CVM-H’). Both observations and simulations are used in dynamic analysis with a finite-element model of an existing high-rise with ~6-second fundamental horizontal periods, located in downtown Los Angeles. The geographical variation in maximum story drift, story-level shear force, and story-level moment values suggest that the excitation of a hypothetical high-rise located in an area characterized by the largest 6-s PSA values could be significantly larger than in a downtown Los Angeles location. Ground motion simulations using the CVM-H velocity model more closely predict the long-period site amplifications in greater Los Angeles, particularly in the south-central San Fernando Valley, than simulations using CVM-S.

Item Type:Conference or Workshop Item (Paper)
Related URLs:
URLURL TypeDescription URL
Kohler, Monica D.0000-0002-4703-190X
Filippitzis, Filippos0000-0001-8377-4914
Graves, Robert0000-0001-9758-453X
Massari, Anthony0000-0002-6561-4674
Heaton, Thomas0000-0003-3363-2197
Clayton, Robert0000-0003-3323-3508
Bunn, Julian0000-0002-3798-298X
Guy, Richard0000-0002-8651-5608
Chandy, K. Mani0000-0001-9190-1290
Additional Information:We are grateful to Caltech, the Betty and Gordon Moore Foundation, the Conrad N. Hilton Foundation, and Computers & Structures, Inc., for providing support for the Community Seismic Network and for this study.
Group:Seismological Laboratory
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
Conrad N. Hilton FoundationUNSPECIFIED
Computers & Structures, IncUNSPECIFIED
Record Number:CaltechAUTHORS:20220518-205134775
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:114801
Deposited By: Monica Kohler
Deposited On:19 May 2022 17:04
Last Modified:19 May 2022 17:04

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