Subsidence, Compaction, and Gravity Sliding: Implications for 3D Geometry, Dynamic Rupture, and Seismic Hazard of Active Basin- Bounding Faults in Southern California

2007 ◽  
Vol 97 (5) ◽  
pp. 1607-1620 ◽  
Author(s):  
C. Nicholson ◽  
M. J. Kamerling ◽  
C. C. Sorlien ◽  
T. E. Hopps ◽  
J.-P. Gratier
Keyword(s):  
Seismic Hazard ◽  
Southern California ◽  
Dynamic Rupture ◽  
3D Geometry

scholarly journals A case for historic joint rupture of the San Andreas and San Jacinto faults

2016 ◽  
Vol 2 (3) ◽  
pp. e1500621 ◽  
Author(s):  
Julian C. Lozos
Keyword(s):  
Seismic Hazard ◽  
Southern California ◽  
San Andreas Fault ◽  
Plate Boundary ◽  
Data Sets ◽  
Dynamic Rupture ◽  
San Jacinto Fault ◽  
Fault Behavior ◽  
San Andreas ◽  
Primary Plate

The San Andreas fault is considered to be the primary plate boundary fault in southern California and the most likely fault to produce a major earthquake. I use dynamic rupture modeling to show that the San Jacinto fault is capable of rupturing along with the San Andreas in a single earthquake, and interpret these results along with existing paleoseismic data and historic damage reports to suggest that this has likely occurred in the historic past. In particular, I find that paleoseismic data and historic observations for the ~M7.5 earthquake of 8 December 1812 are best explained by a rupture that begins on the San Jacinto fault and propagates onto the San Andreas fault. This precedent carries the implications that similar joint ruptures are possible in the future and that the San Jacinto fault plays a more significant role in seismic hazard in southern California than previously considered. My work also shows how physics-based modeling can be used for interpreting paleoseismic data sets and understanding prehistoric fault behavior.

A multidisciplinary approach to seismic hazard in southern California

1994 ◽  
Vol 84 (5) ◽  
pp. 1293-1309
Author(s):  
Steven N. Ward
Keyword(s):  
Seismic Hazard ◽  
Southern California ◽  
Current Model ◽  
Seismic Hazard Assessment ◽  
Historical Seismicity ◽  
San Andreas ◽  
The Pacific ◽  
Moderate Earthquake ◽  
Earthquake Potential ◽  
Seismic Moment Release

Abstract A serious obstacle facing seismic hazard assessment in southern California has been the characterization of earthquake potential in areas far from known major faults where historical seismicity and paleoseismic data are sparse. This article attempts to fill the voids in earthquake statistics by generating “master model” maps of seismic hazard that blend information from geology, paleoseismology, space geodesy, observational seismology, and synthetic seismicity. The current model suggests that about 40% of the seismic moment release in southern California could occur in widely scattered areas away from the principal faults. As a result, over a 30-yr period, nearly all of the region from the Pacific Ocean to 50 km east of the San Andreas Fault has a greater than 50/50 chance of experiencing moderate shaking of 0.1 g or greater, and about a 1 in 20 chance of suffering levels exceeding 0.3 g. For most of the residents of southern California, thelion's share of hazard from moderate earthquake shaking over a 30-yr period derives from smaller, closer, more frequent earthquakes in the magnitude range (5 ≦ M ≦ 7) rather than from large San Andreas ruptures, whatever their likelihood.

scholarly journals Paleoseismology of the southern Panamint Valley fault: Implications for regional earthquake occurrence and seismic hazard in southern California

2013 ◽  
Vol 118 (9) ◽  
pp. 5126-5146 ◽  
Author(s):  
Lee J. McAuliffe ◽  
James F. Dolan ◽  
Eric Kirby ◽  
Chris Rollins ◽  
Ben Haravitch ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Southern California ◽  
Earthquake Occurrence ◽  
Regional Earthquake

On the Comparison of Seismic Ground Motion Simulated by Physics-Based Dynamic Rupture and Predicted by Empirical Attenuation Equations

2021 ◽  
Vol 111 (5) ◽  
pp. 2595-2616 ◽  
Author(s):  
Danhua Xin ◽  
Zhenguo Zhang
Keyword(s):  
Risk Assessment ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Large Earthquake ◽  
Rock Properties ◽  
Motion Prediction ◽  
Ground Motion Prediction ◽  
Dynamic Rupture ◽  
Hazard And Risk ◽  
Hazard And Risk Assessment

ABSTRACT The improvement of ground-motion prediction accuracy is crucial for seismic hazard and risk assessment and engineering practices. Empirically regressed ground-motion prediction equations (GMPEs) are widely used for such purposes in decades. However, the inherent drawbacks of GMPEs, such as the ergodic assumption, lack of near-source observation, and insufficiency to deal with the spatial correlation issue, have motivated geophysicists to find better alternatives. Recent studies on well-recorded earthquakes have illustrated that physics-based simulation (PBS) methods can provide predictions that are comparable to or ever superior to GMPE predictions. The increasing interests in applying PBSs also pose the need to statistically compare these simulations against GMPE predictions or actual observations. We notice the limitations in previous studies focusing on the predictive capability check of PBS. This article is to illustrate how more reasonable check of PBS should be conducted. We consider GMPE works in generally judging the reasonability of PBS, but PBS has the advantage in characterizing the heterogeneity of ground motion of a moderate-to-large earthquake, especially when considering the complexities in fault geometry, regional stress fields, rock properties, surface of the Earth, and site effects. We would rather recommend that, in the future, different GMPEs are only used to preliminarily judge the reasonability of PBS scenarios; then the ground motions simulated by those reasonable PBS scenarios (not limited to one) are further used for the following seismic hazard and risk assessment.

Evaluation of Ground-Motion Models for USGS Seismic Hazard Models Using Near-Source Instrumental Ground-Motion Recordings of the Ridgecrest, California, Earthquake Sequence

2020 ◽  
Vol 110 (4) ◽  
pp. 1517-1529
Author(s):  
Daniel E. McNamara ◽  
Emily L. G. Wolin ◽  
Morgan P. Moschetti ◽  
Eric M. Thompson ◽  
Peter M. Powers ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Southern California ◽  
Epistemic Uncertainty ◽  
Site Amplification ◽  
Earthquake Sequence ◽  
Scoring Method ◽  
Motion Models ◽  
Tectonically Active ◽  
Ground Motion Models

ABSTRACT We evaluated the performance of 12 ground-motion models (GMMs) for earthquakes in the tectonically active shallow crustal region of southern California using instrumental ground-motion observations from the 2019 Ridgecrest, California, earthquake sequence (Mw 4.0–7.1). The sequence was well recorded by the Southern California Seismic Network and rapid response portable aftershock monitoring stations. Ground-motion recordings of this size and proximity are rare, valuable, and independent of GMM development, allowing us to evaluate the predictive powers of GMMs. We first compute total residuals and compare the probability density functions, means, and standard deviations of the observed and predicted ground motions. Next we use the total residuals as inputs to the probabilistic scoring method (log-likelihood [LLH]). The LLH method provides a single score that can be used to weight GMMs in the U.S. Geological Survey (USGS) National Seismic Hazard Model (NSHM) logic trees. We also explore GMM performance for a range of earthquake magnitudes, wave propagation distances, and site characteristics. We find that the Next Generation Attenuation West-2 (NGAW2) active crust GMMs perform well for the 2019 Ridgecrest, California, earthquake sequence and thus validate their use in the 2018 USGS NSHM. However, significant ground-motion residual scatter remains unmodeled by NGAW2 GMMs due to complexities such as local site amplification and source directivity. Results from this study will inform logic-tree weights for updates to the USGS National NSHM. Results from this study support the use of nonergodic GMMs that can account for regional attenuation and site variations to minimize epistemic uncertainty in USGS NSHMs.

CyberShake: A Physics-Based Seismic Hazard Model for Southern California

2010 ◽  
Vol 168 (3-4) ◽  
pp. 367-381 ◽  
Author(s):  
Robert Graves ◽  
Thomas H. Jordan ◽  
Scott Callaghan ◽  
Ewa Deelman ◽  
Edward Field ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Southern California ◽  
Hazard Model

Seismic hazard estimate from background seismicity in southern California

1996 ◽  
Vol 86 (5) ◽  
pp. 1372-1381 ◽  
Author(s):  
Tianqing Cao ◽  
Mark D. Petersen ◽  
Michael S. Reichle
Keyword(s):  
Seismic Hazard ◽  
Southern California ◽  
Seismic Source ◽  
Source Model ◽  
Historical Seismicity ◽  
Rational Approach ◽  
Smoothing Function ◽  
Background Seismicity ◽  
Seismic Source Model ◽  
Seismicity Catalog

Abstract We analyzed the historical seismicity in southern California to develop a rational approach for calculating the seismic hazard from background seismicity of magnitude 6.5 or smaller. The basic assumption for the approach is that future earthquakes will be clustered spatially near locations of historical mainshocks of magnitudes equal to or greater than 4. We analyzed the declustered California seismicity catalog to compute the rate of earthquakes on a grid and then smoothed these rates to account for the spatial distribution of future earthquakes. To find a suitable spatial smoothing function, we studied the distance (r) correlation for southern California earthquakes and found that they follow a 1/rµ power-law relation, where µ increases with magnitude. This result suggests that larger events are more clustered in space than smaller earthquakes. Assuming the seismicity follows the Gutenberg-Richter distribution, we calculated peak ground accelerations (PGA) for 10% probability of exceedance in 50 yr. PGA estimates range between 0.25 and 0.35 g across much of southern California. These ground-motion levels are generally less than half the levels of hazard that are obtained using the entire seismic source model that also includes geologic and geodetic data. We also calculated the overall uncertainty for the hazard map using a Monte Carlo method and found that the coefficient of variation is about 0.24 ± 0.01 for much of the region.

Physics-based constraints for probabilistic seismic hazard assessment in Húsavík–Flatey fault zone, Northern Iceland

2020 ◽  
Author(s):  
Bo Li ◽  
Alice-Agnes Gabriel ◽  
Sara A. Wirp ◽  
Thomas Chartier ◽  
Thomas Ulrich ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Fault Zone ◽  
Hazard Assessment ◽  
Seismic Hazard Assessment ◽  
Strike Slip ◽  
Probabilistic Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard ◽  
Dynamic Rupture ◽  
Complex Fault

<p>Probabilistic seismic hazard assessment (PSHA) is widely used to generate national seismic hazard maps, design building codes for earthquake resilient structures, determine earthquake insurance rates, and in general for the management of seismic risk. However, standard PSHA is generally based on empirical, time-independent assumptions that are simplified and not based on earthquake physics. Physics-based numerical models such as dynamic rupture simulations account for the non-linear coupling of source, path and site effects, which can be significant in their respective contributions depending on the generally complex geological environment (e.g., Wollherr et al., 2019), and could potentially complement standard PSHA. In this study we demonstrate the benefits of such an approach by modeling various rupture scenarios in the complex Húsavík–Flatey fault zone (HFFZ), Northern Iceland. The HFFZ consists of multiple right-lateral strike slip segments distributed across ~100 km. The moment accumulated on the HFF since the last major earthquake in 1872 can result in an earthquake of magnitude 6.8 to 7 (Metzger and Jonsson, 2014) posing a high risk to Húsavík’s community, flourishing tourism and heavy industry.</p><p>We perform high-resolution 3D dynamic rupture simulations using the open-source software SeisSol (www.seissol.org), which can efficiently model spontaneous earthquake rupture across complex fault networks and seismic wave propagation with high order accuracy in space and time. Our models incorporate regional topography, bathymetry, 3D subsurface structure and varying models of the complex fault network while accounting for off-fault damage.</p><p>Synthetic ground motions suggest highly heterogenous radiation patterns and intense localization of shaking in the vicinity of geometric complexities, such as fault bends or rupture transition between segments. In our models, the hypocenter location does not affect the plausible moment magnitude of large events. However, changes in rupture directivity affect the spatial distribution of ground motion significantly.  We run hundreds of dynamic rupture scenarios to generate a physics-based dynamic earthquake catalog of mechanically plausible events. Based on this, we identify a possible maximum magnitude earthquake and generate model-based ground motion prediction equations to complement standard empirical ground motion models. In addition, we use the open-source python code SHERIFs (Chartier et al., 2019) to estimate the likelihood of each rupture event, which is mainly constrained by the fault slip rate estimated and fault-to-fault (f2f) rupture scenarios that are determined by the dynamic simulations. Finally, combining the fault seismic rates and the f2f probabilities with dynamic rupture scenarios and the OpenQuake framework allows us to perform physics-based PSHA for the HFFZ, the largest strike-slip fault in Iceland.</p>

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