EERI Distinguished Lecture at SCEC: October 28, 2009

EERI Southern California Chapter Meeting – Wednesday, October 28, 2009

EERI Distinguished Lecture: "The State of the Practice of Seismic Hazard Analysis: From the Good to the Bad"

Speaker: Dr. Norm Abrahamson

Southern California Earthquake Center
USC Campus, Zumberge Hall of Science

Directions and parking information:

http://www.scec.org/aboutscec/maps/room169psx.html

Time: 4:00 to 5:30 pm

RSVP: eeri@sbcglobal.net

Dr. Norman A. Abrahamson, a senior engineering seismologist in the Geosciences Department at Pacific Gas and Electric Company in San Francisco, will deliver the 2009 Distinguished Lecture to the Southern California Chapter. Dr. Abrahamson presented this lecture at the 2009 EERI Annual Meeting and it was well received.

Dr. Abrahamson will review the state of the practice of seismic hazard analysis and development of design time histories. He observes that the practice of seismic hazard analysis varies tremendously from poor to very good. The large variability in practice is not simply a reflection of project budgets, as a large variation exists for similar scale projects. Although the basic methodology for seismic hazard analysis has been well established, there remains widespread misunderstanding of the basic concepts that contribute to poor practice. Dr. Abrahamson will describe some of the most common misunderstandings and common aspects of bad practice, and will summarize the aspects of good practice that should be expected for low-end and high-end studies.

For the development of design time histories, Dr. Abrahamson will indicate that the state of practice is more variable than for seismic hazard analysis. Key aspects such as how representative time histories are selected and how they are modified (by scaling or by spectral matching) vary tremendously based on the opinions of the project participants or reviewers. In most cases, these opinions are based on "comfort" level rather than objective technical criteria. Abrahamson showed examples that illustrate the large range of quality of current practice. He will state that the state of practice for developing time histories will not improve until objective quantitative criteria are developed to judge the appropriateness of the non-stationary aspects of the proposed time histories for the particular project.