The widespread damage to buildings and loss of life after the Mw7.8 Pazarcik earthquake on February 6, 2023, carries critical implications for evaluating earthquake hazards, and risks in California and across the globe. This event and the subsequent aftershocks in Turkey were, by many measures, larger and more destructive than expected based on historical records. Similar strike-slip faulting in California, particularly along faults like the San Andreas, is expected to produce high rupture speeds resulting in comparable ground velocities to those observed during the 2023 Turkey earthquakes in the northern Los Angeles Basin. This study examines the seismic responses of two existing buildings in the downtown Los Angeles area subjected to earthquake ground motions recorded during the 2023 Pazarcik earthquake through numerical simulations. The simulations are carried out with nonlinear analysis models with dynamic properties that have been validated by local earthquake data recorded in the buildings. Preliminary findings from these analyses reveal calculated story drifts that substantially exceed California building code limits. These findings may be used to contextualize and better understand seismic performance of existing high-rise buildings in Los Angeles area subjected to very large earthquakes.
", "doi": "10.7907/dp9ge-y6d89", "publisher": "Earthquake Engineering Research Institute", "publication_date": "2026" }, { "id": "authors:xjtby-jg473", "collection": "authors", "collection_id": "xjtby-jg473", "cite_using_url": "https://authors.library.caltech.edu/records/xjtby-jg473", "type": "book", "title": "Recovery of Permanent Fault Displacement Through Community Seismic Network (CSN)", "book_title": "Proceedings of the 13th National Conference on Earthquake Engineering", "author": [ { "family_name": "Hyun", "given_name": "Gloria" }, { "family_name": "Kishida", "given_name": "Tadahiro" }, { "family_name": "Kohler", "given_name": "Monica D.", "orcid": "0000-0002-4703-190X", "clpid": "Kohler-M-D" }, { "family_name": "Bozorgnia", "given_name": "Yousef" }, { "family_name": "Guy", "given_name": "Richard" } ], "abstract": "Permanent fault displacement, or “fling step,” can cause significant damage to distributed lifelines, such as water and natural gas transmission pipelines, crossing active earthquake faults. Hence, the detection of, and timely reaction to, fling steps are critical for damage control. Shake table testing was conducted to investigate the feasibility of the fling step derivation using Community Seismic Network (CSN) seismic sensors. CSN consists of cost-effective, tri-axial, micro-electromechanical system (MEMS) accelerometers that record accelerations together with a cloud-based server that in near real-time processes the data 24/7 to be transmitted for rapid decision-making. High-resolution instruments, ETNA2 and Obsidian, were also tested alongside CSN for comparison. Main observations indicate that 1) CSN sensors, albeit with higher internal noise level, are capable of capturing acceleration time series from the shake tests with acceptable accuracy similar to ETNA2 and Obsidian; 2) The shake test data indicate good signal-to-noise ratios; hence the accuracy in fling step extraction through double integration is relatively high for both types of sensors; and 3) Fling step results using CSN shake test data are generally in good agreement with those of ETNA2s and Obsidians. In summary, the CSN sensor package is a promising instrument for approximation of fling steps.
", "doi": "10.7907/xjtby-jg473", "publisher": "Earthquake Engineering Research Institute", "publication_date": "2026" }, { "id": "authors:2hv3f-r4y81", "collection": "authors", "collection_id": "2hv3f-r4y81", "cite_using_url": "https://authors.library.caltech.edu/records/2hv3f-r4y81", "type": "book", "title": "Vertical Frequency Identification of Instrumented Buildings via Data\u2011Driven and Simulation Approaches", "book_title": "Proceedings of the 13th National Conference on Earthquake Engineering", "author": [ { "family_name": "Bolourani", "given_name": "Anahita" }, { "family_name": "Burton", "given_name": "Henry" }, { "family_name": "Bozorgnia", "given_name": "Yousef" }, { "family_name": "Kohler", "given_name": "Monica D.", "orcid": "0000-0002-4703-190X", "clpid": "Kohler-M-D" } ], "abstract": "This paper presents an integrated workflow for identifying the vertical natural frequencies of instrumented mid-rise buildings by combining data-driven analysis of earthquake recordings with finite-element modal analysis. Floor-distributed triaxial Community Seismic Network (CSN) sensors on all levels enable computation of Fourier amplitude spectra and Power Spectral Density (PSD), while floor-to-base transfer and coherence functions are used to isolate structural resonances. In parallel, a detailed numerical model is used for modal analysis and stiffness-perturbation studies that differentiate global vertical modes from slab-dominated vibrations. Cross-validation of measured and simulated responses of a well-instrumented mid-rise building demonstrates consistent resonant bands across events and floors. The simulation-based results provide physical interpretations that are constrained by the findings from the data-driven analyses. Notably, the dominant peak observed in the PSD is attributed to the global vertical mode of the structure rather than slab vibration. The study showcases the integration of dense seismic recordings with simulation to characterize vertical structural frequencies, offering a pathway to improved understanding of building response to vertical shaking.
", "doi": "10.7907/2hv3f-r4y81", "publisher": "Earthquake Engineering Research Institute", "publication_date": "2026" }, { "id": "authors:3xeq4-nwg95", "collection": "authors", "collection_id": "3xeq4-nwg95", "cite_using_url": "https://authors.library.caltech.edu/records/3xeq4-nwg95", "type": "book", "title": "Implementation Strategies and Utility of a Multi-sensor Suite Deployed in a Full-scale 10-story Building Shake Table Test Program", "book_title": "Proceedings of the 13th National Conference on Earthquake Engineering", "author": [ { "family_name": "Sorosh", "given_name": "Shokrullah" }, { "family_name": "Zhang", "given_name": "Jiachen" }, { "family_name": "Lotfizadeh", "given_name": "Koorosh" }, { "family_name": "Haddadi", "given_name": "Hamid" }, { "family_name": "Swensen", "given_name": "Daniel" }, { "family_name": "Branum", "given_name": "Dave" }, { "family_name": "Kohler", "given_name": "Monica D.", "orcid": "0000-0002-4703-190X", "clpid": "Kohler-M-D" }, { "family_name": "Guy", "given_name": "Richard" }, { "family_name": "Skolnik", "given_name": "Derek" }, { "family_name": "Saifullah", "given_name": "M. Khalid" }, { "family_name": "Schafer", "given_name": "Benjamin W." }, { "family_name": "Hutchinson", "given_name": "Tara C." } ], "abstract": "Accurate measurement of the inertial and deformation responses of buildings under lateral dynamic loading is critical for advancing seismic design and modeling tools. Recent advances in sensing technologies enable reliable measurement of structural vibrations across a wide range of loading scenarios. This study investigates the deployment of three types of accelerometers with distinct features, specifications, and configurations to measure the acceleration response of a full-scale 10-story building tested on a multi-directional shake table. The recorded acceleration data are processed using a validated double-integration algorithm to estimate displacement responses, which are then compared against ground-truth displacement time histories obtained from Global Navigation Satellite System (GNSS) sensors deployed at multiple levels of the building. Results demonstrate that all three accelerometer types are capable of accurately capturing both inertial (acceleration) and deformation (displacement) responses, supporting their use in performance assessment and resilience-oriented monitoring of tall buildings.
", "doi": "10.7907/3xeq4-nwg95", "publisher": "Earthquake Engineering Research Institute", "publication_date": "2026" }, { "id": "authors:461e1-tsj53", "collection": "authors", "collection_id": "461e1-tsj53", "cite_using_url": "https://authors.library.caltech.edu/records/461e1-tsj53", "type": "book", "title": "Tracking Multiple-Mode Frequency Changes in a 10-Story Cold-Formed Steel Building to Assess Damage", "book_title": "Proceedings of the 13th National Conference on Earthquake Engineering", "author": [ { "family_name": "Guo", "given_name": "Huiyun", "orcid": "0000-0002-8516-4244", "clpid": "Guo-Huiyun" }, { "family_name": "Zhang", "given_name": "Shun (Shane)", "clpid": "Zhang-Shun-Shane" }, { "family_name": "Kohler", "given_name": "Monica D.", "orcid": "0000-0002-4703-190X", "clpid": "Kohler-M-D" }, { "family_name": "Guy", "given_name": "Richard" }, { "family_name": "Sorosh", "given_name": "Shokrullah" }, { "family_name": "Zhang", "given_name": "Jiachen" }, { "family_name": "Hutchinson", "given_name": "Tara C." } ], "abstract": "We report frequency\u2010domain observations from a full-scale, 10-story, cold-formed steel building tested on the 6-degrees-of-freedom Large High-Performance Outdoor Shake Table at UC San Diego where 76 triaxial Community Seismic Network accelerometers recorded continuous waveforms prior to, during, and after increasing-intensity earthquake tests. Spectrograms of the continuous ambient data reveal persistent, elevation-dependent bands of high energy at both fundamental and higher building modes. During a representative earthquake input (MID16, 1989 Mw 6.9 Loma Prieta motion scaled at Design Earthquake level), the data from a sensor at Level 7, for example, shows that the fundamental mode frequencies decrease at the onset by ~0.60 Hz (X direction, EW) and ~0.55 Hz (Y direction, NS), and recover within ~50 s to final residual reductions of about 0.1 Hz. The third mode shows a larger permanent decrease (~0.2 Hz). These results are consistent with transient softening and frictional slip during the test followed by small but measurable residual stiffness changes afterward. Stiffness loss is confirmed by observed physical damage, most notably rotation and pull-through of fasteners attaching gypsum sheathing to CFS-framing.
", "doi": "10.7907/461e1-tsj53", "publisher": "Earthquake Engineering Research Institute", "publication_date": "2026" } ]