Seismic Hazard Function Mapping Using Estimated Horizontal Crustal Strain Off West Coast Northern Sumatra

A seismic hazard study and analysis of the megathrust source off the west coast of North Sumatra, Indonesia, were conducted based on the estimated horizontal crustal strain using the surface displacement data. This area was selected due to the availability of pre- and co-seismic Global Positioning System (GPS) data for the 2005 Nias–Simeulue Mw 8.6 event. This study aimed to estimate the seismic hazard function (SHF), which is expressed as peak ground acceleration (PGA) versus probability of exceedance (PE), for a 500 years return period using GPS data. The source area model of the Mw 8.6 event is determined based on the co-seismic GPS data. The horizontal crustal strain of the source area is estimated using least square prediction employing local covariance functions based on the horizontal displacement data. The Mw 8.6 return period is estimated by dividing the sum of the co-seismic seismic moment by the pre-seismic seismic moment based on GPS data. The seismicity rate model above a magnitude of completeness is then estimated assuming the b-value of 1 obtained on the previous study’s earthquake catalog data in the region. We show that the SHF based on the study area’s horizontal crustal strain is higher than the one based on earthquake catalogs and estimated geological sliprate data. This discrepancy is associated with the static stress increase (Coulomb failure stress, CFS) of about 0.25 bar imparted by the 2004 Aceh Mw 9.1 event that occurred in the north of the study region. We interpreted that the increase of the SHF was due to the increase in the region’s stress load, which was well documented by the GPS data.

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Probabilistic Seismic Hazard Assessment for United Arab Emirates, Qatar and Bahrain

Applied Sciences ◽

10.3390/app10217901 ◽

2020 ◽

Vol 10 (21) ◽

pp. 7901

Author(s):

Rashad Sawires ◽

José A. Peláez ◽

Mohamed Hamdache

Keyword(s):

Seismic Hazard ◽

United Arab Emirates ◽

Hazard Assessment ◽

Return Period ◽

Seismic Hazard Assessment ◽

Probabilistic Seismic Hazard Assessment ◽

Probabilistic Seismic Hazard ◽

Earthquake Catalog ◽

Intermediate Depth ◽

Seismic Source Models

A probabilistic seismic hazard assessment in terms of peak ground acceleration (PGA) and spectral acceleration (SA) values, for both 10% and 5% probability of exceedance in 50 years, has been performed for the United Arab Emirates, Qatar, and Bahrain. To do that, an updated, unified, and Poissonian earthquake catalog (since 685 to 2019) was prepared for this work. Three alternative seismic source models were considered in a designed logic-tree framework. The discrimination between the shallow and intermediate depth seismicity along the Zagros and the Makran regions was also considered in this assessment. Three alternative ground-motion attenuation models for crustal earthquakes and one additional for intermediate-depth ones have been selected and applied in this study, considering the predominant stress regime computed previously for each defined source. This assessment highlights that the maximum obtained hazard values are observed in the northeastern part of the studied region, specifically at Ras Al-Khaimah, Umm Al-Quwain, and Fujaira, being characterized by mean PGA and SA (0.2 s) pair values equal to (0.13 g, 0.30 g), (0.12 g, 0.29 g), and (0.13 g, 0.28 g), respectively, for a 475-year return period and for B/C National Earthquake Hazards Reduction Program (NEHRP) boundary site conditions. Seismic hazard deaggregation in terms of magnitude and distance was also computed for a return period of 475 years, for ten emirates and cities, and for four different spectral periods.

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Unraveling seismic hazard by estimating prolonged crustal strain buildup in Kumaun-Garhwal, Northwest Himalaya using GPS data measurements

Journal of Asian Earth Sciences ◽

10.1016/j.jseaes.2021.104993 ◽

2021 ◽

pp. 104993

Author(s):

S. Kannaujiya ◽

R.K. Yadav ◽

P.K. Champati ray ◽

T. Sarkar ◽

G. Sharma ◽

...

Keyword(s):

Seismic Hazard ◽

Gps Data ◽

Northwest Himalaya ◽

Crustal Strain

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A Regionalized Seismicity Model for Subduction Zones Based on Geodetic Strain Rates, Geomechanical Parameters, and Earthquake‐Catalog Data

Bulletin of the Seismological Society of America ◽

10.1785/0120190034 ◽

2019 ◽

Vol 109 (5) ◽

pp. 2036-2049 ◽

Cited By ~ 1

Author(s):

José Antonio Bayona Viveros ◽

Sebastian von Specht ◽

Anne Strader ◽

Sebastian Hainzl ◽

Fabrice Cotton ◽

...

Keyword(s):

Seismic Hazard ◽

Seismic Moment ◽

Subduction Zones ◽

Earthquake Activity ◽

Earthquake Catalog ◽

Strain Rates ◽

Earthquake Forecast ◽

Earthquake Parameters ◽

Seismicity Rates ◽

Geodetic Strain

Abstract The Seismic Hazard Inferred from Tectonics based on the Global Strain Rate Map (SHIFT_GSRM) earthquake forecast was designed to provide high‐resolution estimates of global shallow seismicity to be used in seismic hazard assessment. This model combines geodetic strain rates with global earthquake parameters to characterize long‐term rates of seismic moment and earthquake activity. Although SHIFT_GSRM properly computes seismicity rates in seismically active continental regions, it underestimates earthquake rates in subduction zones by an average factor of approximately 3. We present a complementary method to SHIFT_GSRM to more accurately forecast earthquake rates in 37 subduction segments, based on the conservation of moment principle and the use of regional interface seismicity parameters, such as subduction dip angles, corner magnitudes, and coupled seismogenic thicknesses. In seven progressive steps, we find that SHIFT_GSRM earthquake‐rate underpredictions are mainly due to the utilization of a global probability function of seismic moment release that poorly captures the great variability among subduction megathrust interfaces. Retrospective test results show that the forecast is consistent with the observations during the 1 January 1977 to 31 December 2014 period. Moreover, successful pseudoprospective evaluations for the 1 January 2015 to 31 December 2018 period demonstrate the power of the regionalized earthquake model to properly estimate subduction‐zone seismicity.

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Application of the bootstrap method to quantify uncertainty in seismic hazard estimates

Bulletin of the Seismological Society of America ◽

10.1785/bssa0820010104 ◽

1992 ◽

Vol 82 (1) ◽

pp. 104-119

Author(s):

Michéle Lamarre ◽

Brent Townshend ◽

Haresh C. Shah

Keyword(s):

Confidence Interval ◽

Seismic Hazard ◽

Statistical Method ◽

Bootstrap Method ◽

Earthquake Magnitude ◽

Earthquake Catalog ◽

Uncertainty Measure ◽

Attenuation Models ◽

The Bootstrap Method

Abstract This paper describes a methodology to assess the uncertainty in seismic hazard estimates at particular sites. A variant of the bootstrap statistical method is used to combine the uncertainty due to earthquake catalog incompleteness, earthquake magnitude, and recurrence and attenuation models used. The uncertainty measure is provided in the form of a confidence interval. Comparisons of this method applied to various sites in California with previous studies are used to confirm the validity of the method.

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Simulation-Based Seismic Hazard Assessment Using Monte-Carlo Earthquake Catalogs: Application to CyberShake

Bulletin of the Seismological Society of America ◽

10.1785/0120200375 ◽

2021 ◽

Author(s):

Sarah Azar ◽

Mayssa Dabaghi

Keyword(s):

Monte Carlo ◽

Seismic Hazard ◽

Ground Motion ◽

Seismic Hazard Assessment ◽

Computational Time ◽

Earthquake Catalog ◽

Earthquake Catalogs ◽

Earthquake Scenarios ◽

Simulation Based ◽

Hazard Curves

ABSTRACT The use of numerical simulations in probabilistic seismic hazard analysis (PSHA) has achieved a promising level of reliability in recent years. One example is the CyberShake project, which incorporates physics-based 3D ground-motion simulations within seismic hazard calculations. Nonetheless, considerable computational time and resources are required due to the significant processing requirements imposed by source-based models on one hand, and the large number of seismic sources and possible rupture variations on the other. This article proposes to use a less computationally demanding simulation-based PSHA framework for CyberShake. The framework can accurately represent the seismic hazard at a site, by only considering a subset of all the possible earthquake scenarios, based on a Monte-Carlo simulation procedure that generates earthquake catalogs having a specified duration. In this case, ground motions need only be simulated for the scenarios selected in the earthquake catalog, and hazard calculations are limited to this subset of scenarios. To validate the method and evaluate its accuracy in the CyberShake platform, the proposed framework is applied to three sites in southern California, and hazard calculations are performed for earthquake catalogs with different lengths. The resulting hazard curves are then benchmarked against those obtained by considering the entire set of earthquake scenarios and simulations, as done in CyberShake. Both approaches yield similar estimates of the hazard curves for elastic pseudospectral accelerations and inelastic demands, with errors that depend on the length of the Monte-Carlo catalog. With 200,000 yr catalogs, the errors are consistently smaller than 5% at the 2% probability of exceedance in 50 yr hazard level, using only ∼3% of the entire set of simulations. Both approaches also produce similar disaggregation patterns. The results demonstrate the potential of the proposed approach in a simulation-based PSHA platform like CyberShake and as a ground-motion selection tool for seismic demand analyses.

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Seismogenic nodes as a viable alternative to seismogenic zones and observed seismicity for the definition of seismic hazard at regional scale

Vietnam Journal of Earth Sciences ◽

10.15625/0866-7187/41/4/14233 ◽

2019 ◽

Vol 41 (4) ◽

pp. 289-304 ◽

Cited By ~ 2

Author(s):

Paolo Rugarli ◽

Franco Vaccari ◽

Giuliano Panza

Keyword(s):

Seismic Hazard ◽

Safety Factor ◽

Seismic Moment ◽

Regional Scale ◽

Seismic Hazard Assessment ◽

Hazard Maps ◽

Earthquake Catalogues ◽

Definition Of ◽

Partial Factor ◽

Seismogenic Nodes

A fixed increment of magnitude is equivalent to multiply the seismic moment by a factor γEM related to the partial factor γq acting on the seismic moment representing the fault. A comparison is made between the hazard maps obtained with the Neo-Deterministic Seismic Hazard Assessment (NDSHA), using two different approaches: one based on the events magnitude, listed in parametric earthquake catalogues compiled for the study areas, with sources located within the seismogenic zones; the other uses the seismogenic nodes identified by means of pattern recognition techniques applied to morphostructural zonation (MSZ), and increases the reference magnitude by a constant amount tuned by the safety factor γEM.Using γEM=2.0, in most of the territory the two approaches produce totally independent, comparable hazard maps, based on the quite long Italian catalogue. This represents a validation of the seismogenic nodes method and a tuning of the safety factor γEM at about 2.

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A declustered earthquake catalog for the Iranian Plateau

Annals of Geophysics ◽

10.4401/ag-6395 ◽

2015 ◽

Vol 57 (6) ◽

Author(s):

Seyed Hasan Mousavi-Bafrouei ◽

Noorbakhsh Mirzaei ◽

Elham Shabani

Keyword(s):

Seismic Hazard ◽

Hazard Analysis ◽

Time Windows ◽

Recurrence Time ◽

Earthquake Catalog ◽

Magnitude Of Completeness ◽

Iranian Plateau ◽

Seismic Stations ◽

International Agencies ◽

Seismotectonic Province

A unified catalog of earthquakes in Iran and adjacent regions (the area bounded in 22º-42ºN and 42º-66ºE) covering the period of 4th century B.C. through 2012 with Mw≥4 is provided. The catalog includes all events for which magnitude have been determined by international agencies and most reliable individual sources. Since the recurrence time of maximum credible earthquake cannot be directly estimated from the mb, empirical formulae are established to convert mb to Ms, mb to Mw and Ms to Mw for each major seismotectonic province separately. The unified catalog is declustered using conjugated distance-time windows. In order to estimate completeness thresholds, magnitude-time (M-T) diagram and Stepp’s method are applied on the declustered catalog for each seismotectonic province. The magnitude of completeness (Mc) decreases with development of local and regional seismic stations. The results of present study are particularly important in seismic hazard analysis in Iran.

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