Understanding and modeling variability of ground motion is essential for building accurate and precise ground motion prediction equations, which can net site‐specific characterization and reduced hazard levels. Here, we explore the spatial variability in peak ground velocity (PGV) at Sage Brush Flats along the San Jacinto Fault in Southern California. We use data from a dense array (0.6 × 0.6 km2, 1,108 geophones, station spacings 10–30 m) deployed in 2014 for ~1 month. These data offer an opportunity to study small‐scale variability in this region. We examine 38 earthquakes (2 ≤ ML ≤ 4.2) within 200 km of the array. Fault strands and a small basin impact the ground motions, producing PGV variations up to 22% of the mean and a 40% reduction in
Over 2000 buildings were surveyed by members of the Colegio de Ingenieros (CICM) and Sociedad Mexicana de Ingenieria Estructural (SMIE) in Mexico City following the Puebla-Morelos Earthquake of 2017. This inventory of surveyed buildings included nearly 40 collapses and over 600 buildings deemed to have structural damage. Correlation of damage with peak ground acceleration (PGA), peak ground velocity (PGV), predominant spectral period, building location, and building properties including height, estimated stiffness, and presence of walls or retrofits was investigated for the surveyed buildings. The evidence available suggests that (1) ground motion intensity (PGV) drove the occurrence of damage and (2) buildings with more infill and stiff retrofit systems did better than other buildings.
more » « less- NSF-PAR ID:
- 10514183
- Publisher / Repository:
- SAGE Publications
- Date Published:
- Journal Name:
- Earthquake Spectra
- Volume:
- 36
- Issue:
- 2_suppl
- ISSN:
- 8755-2930
- Format(s):
- Medium: X Size: p. 154-174
- Size(s):
- p. 154-174
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract P andS wave near‐surface velocities. We find along‐fault rupture directivity, source, and path effects can increase PGVs by 167%. Surface PGV measurements exceed the colocated borehole station (depth at 148 m) PGV by factors of 3–10, confirming the impact on PGV from near‐surface fault structures, basins, topography, and amplifications from soft sediments. Consistently, we find high PGVs within the basin structure. A pair of colocated GaML2.6 events produce repeatable PGV values with similar spatial patterns. The average corner frequencies of these two events are 11–16 Hz, and viable measurements of stress drop can differ by 6.45 MPa. Within this small array, the PGV values are variable implying spatial extrapolation of PGV to regions of known faults and basins, even across a small area, should be done with caution. -
more » « less
The FEMA P-58 performance-based earthquake engineering methodology was used to assess the economic losses associated with earthquake damage to nonstructural components of two prototype buildings with post-tensioned cross-laminated timber rocking walls. A suite of 22 far-field ground motions were used for nonlinear time history (NLTH) analysis. Truncated incremental dynamic analysis was used to scale the ground motions, and results of the NLTH analyses were used to develop cumulative distribution functions for inter-story drift and peak floor accelerations. The economic factors assessed in the risk analysis included the expected repair cost with respect to spectral acceleration, the probability of exceeding an expected repair cost for selected time periods, and the expected annual loss over different time periods considering various discount factors. It was determined that the ratio of nonstructural repair cost to total building cost at the design earthquake and maximum considered earthquake was lower for the low-rise building than the mid-rise building. However, the probability of nonstructural damage at the service-level earthquake was lower for the mid-rise building than the low-rise building.
-
more » « less
Significant and widespread liquefaction occurred in İskenderun during the 2023 moment magnitude (Mw) 7.8 Kahramanmaraş earthquake. Liquefaction effects on buildings were observed in several areas of İskenderun, predominantly in areas of reclaimed land and near historic shorelines. Liquefaction-induced building settlements were particularly concentrated in the Çay District, which is almost entirely reclaimed land. Liquefaction-induced ground and building settlements were either marginal or not apparent in areas away from the historical shorelines. Building settlement and ground deformation were documented at 26 buildings in İskenderun through lidar scans and laser-level hand measurements. Liquefaction-induced building settlements ranged from 0 to 740 mm. Building-ground interactions were evident from hogging ground deformations, including cases where buildings deformed nearby ground and damaged nearby buildings, and sagging buildings. Historic land development affected the spatial extent of observed liquefaction-induced building damage. Representative liquefaction-induced building settlement and building interaction case histories are discussed and key insights are shared.
-
more » « less
Abstract Post‐earthquake reconnaissance survey of structural damage is an effective way of documenting and understanding the impact of earthquakes on structures. This article aims at providing an efficient data‐based framework that reduces the required time for reconnaissance missions and predicts the damage intensities for every building in the affected region. We hypothesize that a joint selection of necessary structural and earthquake parameters along with sparse damage observations are sufficient to train a supervised learning algorithm and accurately infer the damage for other buildings in the region. Gaussian process regression is employed to prove the hypothesis for probabilistic inference of different damage indices. The algorithm performs efficiently by selecting a set of diverse and representative buildings for damage observations using K‐medoids clustering. To validate the hypothesis and the proposed method, the algorithm framework is implemented on two severe earthquake simulation testbeds. The impacts of different building and ground motion variables on the damage inference performance are discussed. Furthermore, the effectiveness of observation sampling by clustering in the post‐earthquake damage inference is compared with random sampling.
-
more » « less
Summary Activities related to oil and gas production, especially deep disposal of wastewater, have led to sequences of induced earthquakes in the central United States. This study aims to quantify damage to and seismic losses for light‐frame wood buildings when subjected to sequences of induced, small to moderate magnitude, events. To conduct this investigation, one‐ and two‐story multifamily wood frame buildings are designed, and their seismic response dynamically simulated using three‐dimensional nonlinear models, subjected to ground motion sequences recorded in induced events. Damage is quantified through seismic losses, which are estimated using the FEMA P‐58 methodology. Results show that at levels of shaking experienced in recent earthquakes, minor damage, consisting of cracking of interior finishes and nonstructural damage to plumbing and heating, ventilation, and air conditioning systems, is expected, which is consistent with observed damage in these events. The study also examines how expected losses and building fragility will accumulate and/or change over a sequence of earthquakes. Results indicate that damage quantified in terms of absorbed hysteretic energy tended to accumulate over the sequences; this damage corresponds to elongation or widening of cracks. However, fragility is not significantly altered by damage in a preceding event, meaning structures are not becoming more vulnerable due to existing damage. In addition, sequences of events do not change losses if the building is only repaired once at the end of the sequence, as the worsening of damage does not alter repair actions. If repairs are conducted after each event, though, total seismic losses can increase greatly from the sequence.
