Location

Chicago, Illinois

Session Start Date

4-29-2013

Session End Date

5-4-2013

Abstract

Recent earthquakes, the 2008 Wenchuan, 2009 L’Aquila, 2010 Haiti, and 2011 Christchurch and Japan in particular, have called attention to the probabilistic seismic hazard maps, particularly the ground motions with 10, 5, and 2 percent probabilities of exceedance in 50 years. As discussed in this paper, these ground motions are artifacts because they were produced from probabilistic seismic hazard analysis (PSHA). PSHA is a mathematical formulation derived from a rigorous probability analysis of the distribution of earthquake magnitudes, locations, and ground-motion attenuation. Some of the assumptions and distributions that PSHA is based on have been found to be invalid in earth science, however. In addition, PSHA contains a mathematical error, equating a dimensionless quantity (the annual probability of exceedance—exceedance probability in one year) to a dimensional quantity (the annual frequency of exceedance with the unit of per year [1/yr.]). Thus, PSHA is scientifically flawed, and the resulting seismic-hazard and seismic-risk estimates are artifacts. Use of the probabilistic ground-motion maps could lead to either unsafe or overly conservative engineering design. On the other hand, recent earthquakes, the 2010 Chile and 2011 Japan in particular, also showed that ground motions derived from deterministic seismic hazard analysis (DSHA) provided appropriate engineering design to prevent earthquake disaster.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Seventh Conference

Publisher

Missouri University of Science and Technology

Publication Date

4-29-2013

Document Version

Final Version

Rights

© 2013 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Apr 29th, 12:00 AM May 4th, 12:00 AM

Seismic Hazard Assessment and Design Ground Motion: Lessons Learned From Recent Earthquakes

Chicago, Illinois

Recent earthquakes, the 2008 Wenchuan, 2009 L’Aquila, 2010 Haiti, and 2011 Christchurch and Japan in particular, have called attention to the probabilistic seismic hazard maps, particularly the ground motions with 10, 5, and 2 percent probabilities of exceedance in 50 years. As discussed in this paper, these ground motions are artifacts because they were produced from probabilistic seismic hazard analysis (PSHA). PSHA is a mathematical formulation derived from a rigorous probability analysis of the distribution of earthquake magnitudes, locations, and ground-motion attenuation. Some of the assumptions and distributions that PSHA is based on have been found to be invalid in earth science, however. In addition, PSHA contains a mathematical error, equating a dimensionless quantity (the annual probability of exceedance—exceedance probability in one year) to a dimensional quantity (the annual frequency of exceedance with the unit of per year [1/yr.]). Thus, PSHA is scientifically flawed, and the resulting seismic-hazard and seismic-risk estimates are artifacts. Use of the probabilistic ground-motion maps could lead to either unsafe or overly conservative engineering design. On the other hand, recent earthquakes, the 2010 Chile and 2011 Japan in particular, also showed that ground motions derived from deterministic seismic hazard analysis (DSHA) provided appropriate engineering design to prevent earthquake disaster.