[ { "id": "authors:9gy4y-y4921", "collection": "authors", "collection_id": "9gy4y-y4921", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220518-205134775", "type": "conference_item", "title": "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", "author": [ { "family_name": "Kohler", "given_name": "Monica D.", "orcid": "0000-0002-4703-190X", "clpid": "Kohler-M-D" }, { "family_name": "Filippitzis", "given_name": "Filippos", "orcid": "0000-0001-8377-4914", "clpid": "Filippitzis-Filippos" }, { "family_name": "Graves", "given_name": "Robert", "orcid": "0000-0001-9758-453X", "clpid": "Graves-Robert-W" }, { "family_name": "Massari", "given_name": "Anthony", "orcid": "0000-0002-6561-4674", "clpid": "Massari-Anthony" }, { "family_name": "Heaton", "given_name": "Thomas H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" }, { "family_name": "Clayton", "given_name": "Robert W.", "orcid": "0000-0003-3323-3508", "clpid": "Clayton-R-W" }, { "family_name": "Bunn", "given_name": "Julian J.", "orcid": "0000-0002-3798-298X", "clpid": "Bunn-J" }, { "family_name": "Guy", "given_name": "Richard", "orcid": "0000-0002-8651-5608", "clpid": "Guy-Richard-G" }, { "family_name": "Chandy", "given_name": "K. Mani", "orcid": "0000-0001-9190-1290", "clpid": "Chandy-K-M" } ], "abstract": "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.", "publication_date": "2022-05-19" }, { "id": "authors:eyaa6-hf002", "collection": "authors", "collection_id": "eyaa6-hf002", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180713-133233514", "type": "conference_item", "title": "Community seismic network and localized earthquake situational awareness", "author": [ { "family_name": "Kohler", "given_name": "M. D.", "orcid": "0000-0002-4703-190X", "clpid": "Kohler-M-D" }, { "family_name": "Guy", "given_name": "R.", "clpid": "Guy-R" }, { "family_name": "Bunn", "given_name": "J.", "orcid": "0000-0002-3798-298X", "clpid": "Bunn-J" }, { "family_name": "Massari", "given_name": "A.", "orcid": "0000-0002-6561-4674", "clpid": "Massari-A" }, { "family_name": "Clayton", "given_name": "R.", "orcid": "0000-0003-3323-3508", "clpid": "Clayton-R-W" }, { "family_name": "Heaton", "given_name": "T.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" }, { "family_name": "Chandy", "given_name": "K. M.", "orcid": "0000-0001-9190-1290", "clpid": "Chandy-K-M" }, { "family_name": "Ebrahimian", "given_name": "H.", "clpid": "Ebrahimian-H" }, { "family_name": "Dorn", "given_name": "C.", "orcid": "0000-0001-6516-2586", "clpid": "Dorn-C" } ], "abstract": "Community-hosted seismic networks are a solution to the need for large numbers of sensors to operate over a seismically active region in order to accurately measure the size and location of an earthquake, assess resulting damage, and provide alerts. The Community Seismic Network is one such strong-motion network, currently comprising hundreds of elements located in California. It consists of low-cost, three-component, MEMS accelerometers capable of recording accelerations up to twice the level of gravity. The primary product of the network is to produce measurements of shaking of the ground and multiple locations of every upper floor in buildings, in the seconds during and following a major earthquake. Each sensor uses a small, dedicated ARM processor computer running Linux, and analyzes time series data in real time at hundreds of samples per second. The network reports on shaking parameters that indicate intensity of the structural response levels such as maximum floor acceleration and velocity, displacement of a floor in a building, as well as data products that depend on the response time histories. To do this, Cloud computing has been expanded through the use of statically defined subsets of sensors called cloudlets. These are smaller subsets of similar sensors that carry out customized calculations for those locations. The measurements are reported as rapidly as possible following an earthquake so that they may be incorporated into structural diagnosis and prognosis applications that can be used by first responders to prioritize their initial disaster management efforts. The cloudlet displays are customized for specific buildings and they show in real time: instantaneous displacement, inter-story drift, and resonant frequency and mode shapes using system identification software tools. The real-time display products are useful for decision-making about whether the potential for damage exists, what level of damage may have occurred and where, and whether total business disruption is necessary. City-wide dense monitoring makes it possible for emergency response managers to prioritize the target locations requiring first response on a block-by-block scale based on reports of shaking intensity.", "publication_date": "2018-06" }, { "id": "authors:kmdpr-3pb02", "collection": "authors", "collection_id": "kmdpr-3pb02", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170127-163202195", "type": "conference_item", "title": "Dense Building Instrumentation Application for City-Wide Structural Health Monitoring", "author": [ { "family_name": "Massari", "given_name": "A.", "orcid": "0000-0002-6561-4674", "clpid": "Massari-A" }, { "family_name": "Kohler", "given_name": "M.", "orcid": "0000-0002-4703-190X", "clpid": "Kohler-M-D" }, { "family_name": "Clayton", "given_name": "R.", "orcid": "0000-0003-3323-3508", "clpid": "Clayton-R-W" }, { "family_name": "Guy", "given_name": "R.", "clpid": "Guy-R" }, { "family_name": "Heaton", "given_name": "T.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" }, { "family_name": "Bunn", "given_name": "J.", "orcid": "0000-0002-3798-298X", "clpid": "Bunn-J" }, { "family_name": "Chandy", "given_name": "K. M.", "clpid": "Chandy-K-M" }, { "family_name": "Demetri", "given_name": "D.", "clpid": "Demetri-D" } ], "abstract": "The Community Seismic Network (CSN) has partnered with the NASA Jet Propulsion Laboratory (JPL) to initiate a campus-wide structural monitoring program of all buildings on the premises. The JPL campus serves as a proxy for a densely instrumented urban city with localized vibration measurements collected throughout the free-field and built environment. Instrumenting the entire campus provides dense measurements in a horizontal geospatial sense for soil response; in addition five buildings have been instrumented on every floor of the structure. Each building has a unique structural system as well as varied amounts of structural information via structural drawings, making several levels of assessment and evaluation possible. Computational studies with focus on damage detection applied to the campus structural network are demonstrated for a collection of buildings. For campus-wide real-time and post-event evaluation, ground and building response products using CSN data are illustrating the usefulness of higher spatial resolution compared to what was previously typical with sparser instrumentation.", "publication_date": "2017-01-28" } ]