Earth Science Research Needs for Improving Earthquake Scenarios

Brad T. Aagaard

Submitted August 14, 2018, SCEC Contribution #8554, 2018 SCEC Annual Meeting Talk on Wed 08:30

Earthquake scenarios provide important opportunities to showcase the effectiveness of integrating science from across the spectrum of earthquake hazards research. These scenarios complement probabilistic hazard assessments by examining specific realizations of large, potential earthquakes and their consequences to improve our resilience to natural disasters. They also raise the profile of our research with national media coverage. Consequently, it is especially important to leverage knowledge from earthquake geology, tectonic geodesy, and seismology to create the most realistic earthquake scenarios possible.

The 2008 ShakeOut scenario brought together more than 300 contributors to quantify the hazards and risks associated with a magnitude 7.8 occurring on the southern San Andreas fault. This effort set new expectations for how we develop sophisticated earthquake scenarios. In 2008 the USGS also led a collaborative effort to develop a suite of earthquake ground-motion scenarios for the Hayward fault, one of which is being used as the basis for the more comprehensive HayWired earthquake scenario. Since these scenarios were developed 10 years ago, our science has continued to advance but many open questions persist.

Creating realistic earthquake ruptures remains one of the major challenges. How to select rupture end points, the depth extent of coseismic slip, and multi-fault ruptures are basic issues. Additional research is necessary to constrain rupture details, such as the spatial variability of slip, the potential hypocenter relative to geologic features and microseismicity, and the speed and direction of rupture propagation. Furthermore, we have a limited understanding of when and where we should expect significant afterslip, which impacts infrastructure response planning.

In computing scenario ground motions, research is needed to further develop techniques for incorporating sophisticated, shallow, anelastic behavior into 3D simulations and constraining the anelastic properties at regional scales. Additional work is also necessary to develop regional-scale analysis techniques for estimating the extent and severity of ground failure. Aftershock forecasts can be improved with regional parameters for clustering and fault locations.

Pursuing these research directions will lead to more accurate estimates of the anticipated consequences of large earthquakes and help support better decision-making in urban planning and disaster preparedness.

Key Words
earthquake scenarios

Aagaard, B. T. (2018, 08). Earth Science Research Needs for Improving Earthquake Scenarios. Oral Presentation at 2018 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Engineering Implementation Interface (EEII)