Archive for February, 2013

A new seismic source characterization model for the Central and Eastern United States (CEUS) is publicly available in a form suitable for use in Probabilistic Seismic Hazard Analysis (PSHA – for a PSHA example see NUREG/CR-6607) evaluations for regulatory activities (including Early Site Permit and Combined Operating License Applications for nuclear facilities). Input to a probabilistic seismic hazard analysis for nuclear facilities usually consists of both seismic source characterization and ground motion characterization [an objective of PEER NGA-East is to develop new ground motion characterization model for Central and Eastern North-America]. These characterizations are used to calculate probable hazard results (seismic hazard curves) at a particular site. The new CEUS seismic source model is based on improvements in available data and methods (USGS : Open-File Report 2011-1101).

CEUS Earthquake Catalog

The new CEUS source model replaces the Seismic Hazard Methodology for the Central and Eastern United States (NP-4726-1986 – paper volumes) and Seismic Hazard Characterization of 69 Nuclear Plant Sites East of Rocky Mountains (Bernreuter, 1989). The new seismic source model can be used in a Senior Seismic Hazard Analysis Committee (SSHAC, Budnitz, 1997) Level 3 assessment process as implemented by NUREG (Kammerer and Ake) in evaluating the seismic safety of nuclear facilities.

Two important American Society of Civil Engineers (ASCE) standards are also relevant for the structural engineering design and analysis of nuclear power plants: ASCE 4-98, “Seismic Analysis of Safety-Related Nuclear Structures and Commentary” and ASCE 43-05, “Seismic Design Criteria for Structures, Systems and Components in Nuclear Facilities” as well as a NUREG sponsored evaluation (NUREG/CR-6926 – 2007) of the latter ASCE standard.

Northeastern coastal town in Japan before the 2011 Great East Japan earthquake (Tohoku) and tsunami

The Oregon Seismic Safety Policy Advisory Commission (OSSPAC) has completed a comprehensive review of Oregon’s buildings, lifelines and community priorities to assess how to protect lives and commerce and facilitate recovery from a possible, M=9.0, Cascadia earthquake and tsunami. The “Oregon Resilience Plan” (Executive Summary) maps an ambitious, fifty-year program of policy and investment priorities for the state to offset a predicted $32 billion loss and potentially high mortality rates in coastal Oregon from a large, subduction-zone earthquake and tsunami.
The last megathrust earthquake in the Pacific northwest was in January, 1700, just over 300 years ago. Geological evidence indicates that such great earthquakes have occurred at least seven times in the last 3,500 years, a return interval of 400 to 600 years (Pacific Northwest Seismic Network- PNSN). John J. Clague, “Evidence for large earthquakes at the Cascadia Subduction Zone” (AGU – Review of Geophysics, January 1997) observed that very large, historically unprecedented earthquakes at the Cascadia subduction zone in western North America have left signs of sudden land level change, tsunamis, and strong shaking in coastal sediments. The last earthquake or series of earthquakes is believed to have ruptured the entire 1000-km length of the subduction zone; if this was a single earthquake, it probably exceeded M=9.0. The Cascadia zone earthquake and tsunami recurrence intervals are uncertain because of difficulties in identifying and dating ancient earthquakes. In southwestern Washington state, intervals for the seven most recent earthquakes average about 500 years, but range from less than 200 years to 700–1300 years. It is believed that part of the plate boundary in the subduction border is locked and accumulating elastic strain that will be released during a future large earthquake. Oregon has been assessing its seismic vulnerabilities, especially to a Cascadia subduction event, since at least the 1980s. Assessments provided simulated strong ground motions for two likely Cascadia mega-earthquake scenarios, detailed highway bridge retrofit and strengthening planning and reviews of multi-jurisdictional tsunami warning systems. However, after the 2011 Tohoku (Japan) great earthquake and tsunami provided dramatic lessons for the Pacific Northwest in North America, this OSSPC initiative integrates seismic resilience planning for the State of Oregon under one updated report and starkly lays out the large investment decisions required to achieve greater resiliency. In addition to local and state planning efforts, in the U.S.A., the federal agency, NOAA, is charged with tsunami coastal hazard mitigation, inundation mapping and tsunami forecast. See for example NOAA Technical Memorandum OAR PMEL-135.

The Japanese coastal town several months after the 2011 great earthquake and tsunami

World Housing Encyclopedia and Build-Change

Posted by cdj On February - 1 - 2013

This example of popular, light concrete, gravity framed housing in Colombia is very vulnerable to earthquake shaking or hillslides -- (photo and linked report from image: Luis G. Mejia)

The World Housing Encyclopedia (WHE – multi-criteria search form), a collection of resources related to different housing construction practices in many seismically active areas of the world, attempts to encourage the use of earthquake-resistant housing technologies. Recently, the encyclopedia managers, the Earthquake Engineering Research Institute (EERI) and the Global Earthquake Model (GEM) published this request for assistance from knowledgeable builders, architects and engineers-

The Global Earthquake Model and the World Housing Encyclopedia need your expertise to improve our understanding of the global building stock. You can do this by describing a building or building type in your country using a tool GEM has developed, called TaxT. Your participation will assist GEM in generating a comprehensive, global building taxonomy and further the science of seismic risk reduction. EERI intends to publish, after review, many of these short reports on the WHE website and GEM will also share outcomes. To read about and download the TaxT report form or visit – “”.

BuildChange, an international, non-profit social enterprise that designs earthquake-resistant houses in developing countries and trains local builders, homeowners, engineers, and government officials to build them may offer at least part of a solution to the recurring problem of seismically, unresistant housing located in seismically vulnerable countries of limited resources.
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