On-Demand Webinars

IMPROVED UNDERSTANDING OF EARTHQUAKES AND FAULT ZONES: Requirements for Better Earthquake Hazard Mapping

Earthquake hazard maps are crucial in our efforts to mitigate earthquake hazards. However, recent earthquakes in China, Haiti and Japan have been deadly when they were in areas mapped as 'low earthquake hazard', illustrating problems with hazard mapping. Failure to present earthquake hazards more accurately stems from a number of problems. One of the most difficult problems is over-reliance on the instrumental record, which records less than 100 years of earthquake history. In other words, an active fault that is locked may be storing elastic strain for several centuries and provide little to no indication during the past 100 years that it is nearing full-cycle and capable of producing a large earthquake. Earthquakes are typically more complicated than the models on which hazard maps are based. As a result, key aspects of hazard maps often depend on poorly constrained parameters, whose values are chosen based on the mapmakers' preconceptions. When these are incorrect, maps do poorly.

Because hazard mapping has become widely accepted and used to make major decisions, we must improve current practices. Such testing, which is common and useful in similar fields, will show how well maps actually work and hopefully help produce measurable improvements. There are likely, however, limits on how well hazard maps can ever be made because of the intrinsic variability of earthquake processes.It is thus crucial for users of hazard maps to uncerstand their uncertainties and limitations.

Part 1 of this webinar series will look at a number of timely issues regarding seismic hazard mapping.

HIGHLIGHTS INCLUDE:

• The four reasons why seismic hazard maps go wrong
• Defining the hazard (how? where? when? how big? and how much shaking?)
• Improved tools for constructing and evaluating earthquake hazard maps.
• Understanding the maps' uncertainties and limitations.

Attendees are invited to actively participate during this live and interactive on-line web seminar. Discussion is planned following the webinar for those who want to continue the session. Bring your questions to the webinar and present them to the instructor and other participants for exploring the best solution.