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Exploring Probabilistic Seismic Hazard Assessment in the Energy Domain

Session: Probabilistic Seismic Hazard Assessment: Where Do We Go from Here? II

Type: Oral

Date: 4/20/2021

Presentation Time: 03:00 PM Pacific

Description: 

Contemporary probabilistic seismic hazard assessment (PSHA) is formulated in terms of the moment magnitude. Based on static deformation, the seismic moment is a practical measure of earthquake size. However, it is not a direct measure of the dynamics of an earthquake. An alternative measure of earthquake size based on the dynamics is the radiated energy. While strong correlations between seismic moment and radiated energy exist, showing in empirical conversion relations between the two, recent research indicates that the radiated energy performs better in assessing ground shaking in the relevant frequency band 1 to 10 Hz. This motivates a closer look PSHA in the energy domain.

In this contribution, we consider the seismicity model part of the hazard integral. We present recent results in modeling an area’s stationary seismicity based on the conservation of externally-driven deformation energy. The energy-conserving seismicity framework is the counterpart of the balance of seismic moment in the energy domain. We discuss differences between the two approaches, which are centered on the interplay of stress with respect to strain rates. This leads to challenges but also presents opportunities of seismicity modeling in energy space. Throughout, Southern California serves as an illustrative example and is augmented by simple analytical examples.

Overall, our goal is to spark thought whether working in the energy domain can be a useful new angle to tackle some of the current challenges of PSHA.

Presenting Author: Malte J. Ziebarth

Student Presenter: Yes

Authors