scholarly journals Seismic hazard in western Canada from GPS strain rates versus earthquake catalog

2011 ◽  
Vol 116 (B12) ◽  
Author(s):  
S. Mazzotti ◽  
L. J. Leonard ◽  
J. F. Cassidy ◽  
G. C. Rogers ◽  
S. Halchuk
2010 ◽  
Vol 37 (4) ◽  
pp. 562-575 ◽  
Author(s):  
K. Goda ◽  
H. P. Hong ◽  
G. M. Atkinson

This study provides a preliminary assessment of the impact of new seismological information on the existing seismic hazard model, as implemented in the 2005 National building code of Canada (NBCC); this seismic hazard model was actually developed in the early 1990s, and thus there is significant new information available in the literature since then. A reassessment of seismic hazard is carried out by updating magnitude-recurrence relations based on the earthquake catalog up to the end of 2006, including conversion of all earthquake magnitudes to a homogenous moment magnitude scale. The recent ground-motion prediction equations, which update the knowledge base used in the 2005 NBCC, are also used. Focusing on Vancouver and Victoria, sensitivity analyses are carried out to investigate both individual and combined impacts of these updates on the uniform hazard spectra. The proposed model can be used as a guide to the direction in which future seismic hazard models for western Canada may move.


2019 ◽  
Vol 109 (5) ◽  
pp. 2036-2049 ◽  
Author(s):  
José Antonio Bayona Viveros ◽  
Sebastian von Specht ◽  
Anne Strader ◽  
Sebastian Hainzl ◽  
Fabrice Cotton ◽  
...  

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.


1992 ◽  
Vol 82 (1) ◽  
pp. 104-119
Author(s):  
Michéle Lamarre ◽  
Brent Townshend ◽  
Haresh C. Shah

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.


Author(s):  
Sarah Azar ◽  
Mayssa Dabaghi

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.


2018 ◽  
Vol 45 (20) ◽  
Author(s):  
Honn Kao ◽  
Roy Hyndman ◽  
Yan Jiang ◽  
Ryan Visser ◽  
Brindley Smith ◽  
...  

2015 ◽  
Vol 57 (6) ◽  
Author(s):  
Seyed Hasan Mousavi-Bafrouei ◽  
Noorbakhsh Mirzaei ◽  
Elham Shabani

A unified catalog of earthquakes in Iran and adjacent regions (the area bounded in 22<sup>º</sup>-42<sup>º</sup>N and 42<sup>º</sup>-66<sup>º</sup>E) covering the period of 4<sup>th</sup> century B.C. through 2012 with M<sub>w</sub>≥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 m<sub>b</sub>, empirical formulae are established to convert m<sub>b</sub> to M<sub>s</sub>, m<sub>b</sub> to M<sub>w</sub> and M<sub>s</sub> to M<sub>w</sub> 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 (M<sub>c</sub>) decreases with development of local and regional seismic stations. The results of present study are particularly important in seismic hazard analysis in Iran.


2018 ◽  
Vol 66 (5) ◽  
pp. 931-943 ◽  
Author(s):  
Rodolfo Console ◽  
Massimo Chiappini ◽  
Liliana Minelli ◽  
Fabio Speranza ◽  
Roberto Carluccio ◽  
...  

1999 ◽  
Vol 89 (4) ◽  
pp. 854-866 ◽  
Author(s):  
John E. Ebel ◽  
Alan L. Kafka

Abstract We have developed a Monte Carlo methodology for the estimation of seismic hazard at a site or across an area. This method uses a multitudinous resampling of an earthquake catalog, perhaps supplemented by parametric models, to construct synthetic earthquake catalogs and then to find earthquake ground motions from which the hazard values are found. Large earthquakes extrapolated from a Gutenberg-Richter recurrence relation and characteristic earthquakes can be included in the analysis. For the ground motion attenuation with distance, the method can use either a set of observed ground motion observations from which estimates are randomly selected, a table of ground motion values as a function of epicentral distance and magnitude, or a parametric ground motion attenuation relation. The method has been tested for sites in New England using an earthquake catalog for the northeastern United States and southeastern Canada, and it yields reasonable ground motions at standard seismic hazard values. This is true both when published ground motion attenuation relations and when a dataset of observed peak acceleration observations are used to compute the ground motion attenuation with distance. The hazard values depend to some extent on the duration of the synthetic catalog and the specific ground motion attenuation used, and the uncertainty in the ground motions increases with decreasing hazard probability. The program gives peak accelerations that are comparable to those of the 1996 U.S. national seismic hazard maps. The method can be adapted to compute seismic hazard for cases where there are temporal or spatial variations in earthquake occurrence rates or source parameters.


Author(s):  
Ramin M. H. Dokht ◽  
Brindley Smith ◽  
Honn Kao ◽  
Ryan Visser ◽  
Jesse Hutchinson

2012 ◽  
Vol 12 (5) ◽  
pp. 1321-1325 ◽  
Author(s):  
L. Telesca ◽  
V. Alcaz ◽  
I. Sandu

Abstract. The crustal and sub-crustal seismicity that occurred in the Vrancea area from 1978 to 2008 is investigated. Due to quarry blast contamination, the analysis of the crustal seismicity was restricted to events that occurred between 20 km and 60 km, considering sub-crustal events as all those that occurred at depths larger than 60 km. The completeness magnitude was estimated between 2.3 and 2.5 for the crustal seismicity and between 2.9 and 3.1 for the sub-crustal one. The Gutenberg-Richter b-values show clear differences between crustal and sub-crustal seismicity, with values around 0.9 and 1.3–1.4, respectively. The analysis performed in this study represents a preliminary issue for the seismic hazard assessment of surrounding regions like Moldova, for which the earthquakes generated in Vrancea represent an important threat.


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