scholarly journals Fault-Source-Based Probabilistic Seismic Hazard and Risk Analysis for Victoria, British Columbia, Canada: A Case of the Leech River Valley Fault and Devil’s Mountain Fault System

2021 ◽  
Vol 13 (3) ◽  
pp. 1440
Author(s):  
Katsuichiro Goda ◽  
Andrei Sharipov
Keyword(s):  
British Columbia ◽  
Sensitivity Analysis ◽  
Seismic Hazard ◽  
Seismic Risk ◽  
Earthquake Magnitude ◽  
River Valley ◽  
Fault System ◽  
Probabilistic Seismic Hazard ◽  
Hazard And Risk ◽  
Fault Source

This study develops a fault-source-based seismic hazard model for the Leech River Valley Fault (LRVF) and the Devil’s Mountain Fault (DMF) in southern Vancouver Island, British Columbia, Canada. These faults pose significant risks to the provincial capital, Victoria, due to their proximity and potentially large earthquake magnitudes. To evaluate the effects of including these faults in probabilistic seismic hazard analysis and city-wide seismic loss estimation for Victoria, a comprehensive sensitivity analysis is conducted by considering different fault rupture patterns and different earthquake magnitude models, as well as variations in their parameters. The aim is to assess the relative contributions of the LRVF-DMF system to the overall seismic hazard and risk in Victoria at different return periods. The consideration of the LRVF-DMF system as a potential seismic source increases the seismic risk assessment results by 10 to 30%, especially at the high return period levels. The sensitivity analysis results highlight the importance of determining the slip rate for the fault deformation zone and of specifying the earthquake magnitude models (e.g., characteristic versus truncated exponential models). From urban seismic risk management perspectives, these nearby faults should be considered critical earthquake scenarios.

Definition of Lateral Spread Displacement for Regional Risk Assessments of Pipeline Vulnerability

2010 ◽  
Author(s):  
Douglas G. Honegger ◽  
Mujib Rahman ◽  
Humberto Puebla ◽  
Dharma Wijewickreme ◽  
Anthony Augello
Keyword(s):  
Risk Assessment ◽  
British Columbia ◽  
Seismic Hazard ◽  
Seismic Risk ◽  
Hazard Analysis ◽  
Earthquake Magnitude ◽  
Seismic Hazard Analysis ◽  
Lateral Spread ◽  
Probabilistic Seismic Hazard ◽  
Ground Shaking

Terasen Gas Inc. (Terasen) operates a natural gas supply and distribution system situated within one of the zones of the highest seismic activity in Canada. The region encompasses significant areas underlain by marine, deltaic, and alluvial soil deposits, some of which are considered to be susceptible to liquefaction and large ground movements when subjected to earthquake ground shaking. Terasen undertook an assessment of seismic risks to its transmission and key intermediate pressure pipelines in the Lower Mainland in 1994 [1]. The seismic assessment focused on approximately 500 km of steel pipelines ranging from NPS 8 to NPS 42 and operating at pressures from 1900 to 4020 kPa. The 1994 risk assessment provided the basis for detailed site-specific assessment and seismic upgrade programs to retrofit its existing system to reduce risks to acceptable levels. While the general approach undertaken in 1994 remains technically sound, advancements have been made over the past 15 years in the understanding of earthquake hazards and their impact on pipelines. In particular, estimates of the earthquake ground shaking hazard in British Columbia as published by Geological Survey of Canada (GSC) have recently been updated and incorporated into the 2005 National Building Code of Canada (NBCC). In addition, empirical methods of estimating lateral spread ground displacements have been improved as new case-history information has become available. Given these changes, Terasen decided in 2009 to reexamine the seismic risk to Terasen’s pipelines. The scope of the updated seismic risk study was expanded over that in 1994 to include pipelines on Vancouver Island and the Interior of British Columbia. For regional assessments, estimates of lateral spread displacements are necessarily based upon empirical formulations that relate displacement to variables of earthquake severity (earthquake magnitude and distance), susceptibility to liquefaction (density, grain size, fines content), and topography (distance from a river bank or ground slope). Implementing empirical formulae with the results of probabilistic seismic hazard calculations is complicated by the fact that the empirical approach requires earthquake magnitude and distance, as a parametric couple, to be related to the ground shaking severity. However, but such a relationship does not exist in the estimates of mean or modal earthquake magnitude and distance disaggregated from a probabilistic seismic hazard analysis. This paper presents an overview of the approach to regional risk assessment undertaken by Terasen and discusses the unique approach adopted for determining lateral spread displacements consistent with the probabilistic seismic hazard analysis.

scholarly journals Fault System-Based Probabilistic Seismic Hazard Assessment of a Moderate Seismicity Region: The Eastern Betics Shear Zone (SE Spain)

2020 ◽  
Vol 8 ◽  
Author(s):  
Octavi Gómez-Novell ◽  
Julián García-Mayordomo ◽  
María Ortuño ◽  
Eulàlia Masana ◽  
Thomas Chartier
Keyword(s):  
Seismic Hazard ◽  
Return Period ◽  
Fault System ◽  
Probabilistic Seismic Hazard ◽  
Se Spain ◽  
Slip Rates ◽  
Area Source ◽  
Moderate Seismicity ◽  
Background Seismicity ◽  
Hazard Levels

Including faults as seismogenic sources in probabilistic seismic hazard assessments (PSHA) has turned into a common practice as knowledge of active faults is improving. Moreover, the occurrence of earthquakes in multi-fault ruptures has evidenced the need to understand faults as interacting systems rather than independent sources. We present a PSHA for the Southeastern Spain obtained by including the faults of a moderate seismicity region, the Eastern Betics Shear Zone (EBSZ) in SE Spain, as the main seismogenic sources in two separate source models, one considering background seismicity. In contrast with previous studies in Spain, earthquake occurrence of the EBSZ system is modeled considering different hypotheses of multi-fault ruptures at the whole fault system scale and weighted in a logic tree. We compare the hazard levels with those from an area source PSHA and a previous fault-based approach. The results show a clear control of the EBSZ faults in the seismic hazard for all return periods, increasing drastically the hazard levels in the regions close to the fault traces and influencing up to 20 km farther with respect to the area source PSHA. The seismic hazard is dependent on the fault slip rates as peak ground accelerations and territorial extension of the fault influence appear higher around the Alhama de Murcia and Carboneras faults, while lower slip rate faults (Palomares Fault) show minor contribution to the hazard. For the return period of 475 years and near-fault locations, our models are more consistent with the ground motion values reached in the 2011 Mw 5.2 Lorca event than the building code or national seismic hazard map, which suggest that our fault system-based model performs more accurate estimations for this return period. Fault data, mainly slip rates, and its uncertainties have a clear impact on the seismic hazard and, for some faults, the lack of detailed paleoseismic studies can compromise the reliability of the hazard estimations. This, together with epistemic uncertainties concerning the background seismicity, are key discussion points in the present study, having an impact on further research and aiming to serve as a case example for other low-to-moderate seismicity regions worldwide.

Probabilistic Seismic Hazard Analysis and Synthetic Ground Motion Generation for Seismic Risk Assessment of Structures in the Northeast India

2017 ◽  
Vol 8 (2) ◽  
pp. 39-59 ◽  
Author(s):  
Swarup Ghosh ◽  
Subrata Chakraborty
Keyword(s):  
Risk Assessment ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Seismic Risk ◽  
Hazard Analysis ◽  
Probabilistic Seismic Hazard Analysis ◽  
Seismic Hazard Analysis ◽  
Probabilistic Seismic Hazard ◽  
Seismic Risk Assessment ◽  
Site Specific

This article outlines the performance-based seismic risk assessment (PBSRA) of structures requiring probabilistic seismic hazard analysis (PSHA) to obtain hazard curves and an evaluation of the demand model by a nonlinear structural response analysis under properly selected ground motion records. Unfortunately, such site-specific information is not readily available for Northeast region of India. The present study focuses on these two aspects to supplement the PBSRA. The estimations of hazard curves are demonstrated by considering the seismicity within 300 km radius around the considered locations and specified exposure period. Due to limited availability of natural records in this region, synthetic accelerograms are generated using stochastic point source models by identifying the most contributing magnitude distance combinations from disaggregation of the PSHA results. The significant variabilities observed in the estimated hazard, synthetic accelerograms and nonlinear building responses in the various locations indicate the need of explicit site-specific analysis for PBRSA of structures in the region.

scholarly journals Hazard and risk assessments for induced seismicity in Groningen

2017 ◽  
Vol 96 (5) ◽  
pp. s259-s269 ◽  
Author(s):  
Jan van Elk ◽  
Dirk Doornhof ◽  
Julian J. Bommer ◽  
Stephen J. Bourne ◽  
Steve J. Oates ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Seismic Hazard ◽  
Data Acquisition ◽  
Induced Seismicity ◽  
Research Programme ◽  
Gas Production ◽  
Probabilistic Seismic Hazard ◽  
Gas Field ◽  
Hazard And Risk ◽  
Hazard And Risk Assessment

AbstractEarthquakes associated with gas production have been recorded in the northern part of the Netherlands since 1986. The Huizinge earthquake of 16 August 2012, the strongest so far with a magnitude of ML = 3.6, prompted reassessment of the seismicity induced by production from the Groningen gas field. An international research programme was initiated, with the participation of many Dutch and international universities, knowledge institutes and recognised experts.The prime aim of the programme was to assess the hazard and risk resulting from the induced seismicity. Classic probabilistic seismic hazard and risk assessment (PSHA) was implemented using a Monte Carlo method. The scope of the research programme extended from the cause (production of gas from the underground reservoir) to the effects (risk to people and damage to buildings). Data acquisition through field measurements and laboratory experiments was a substantial element of the research programme. The existing geophone and accelerometer monitoring network was extended, a new network of accelerometers in building foundations was installed, geophones were placed at reservoir level in deep wells, GPS stations were installed and a gravity survey was conducted.Results of the probabilistic seismic hazard and risk assessment have been published in production plans submitted to the Minister of Economic Affairs, Winningsplan Groningen 2013 and 2016 and several intermediate updates. The studies and data acquisition further constrained the uncertainties and resulted in a reduction of the initially assessed hazard and risk.

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