← Back to Sessions

Using Comparative Subductology to Constrain Future Subduction Zone Earthquake Losses

Description: 

On its hundredth anniversary, we recount details of the M8 September 1923 Great Kanto earthquake, the most devastating natural disaster in Japanese historical times. This event destroyed most of Yokohama and Tokyo, attributable to the combined impacts of shaking, liquefaction, landslides, tsunami, and (primarily) fires, which resulted in over 105,000 fatalities. Although smaller in magnitude than other great Japanese earthquakes, including the M9 2011 Tohoku earthquake, the proximity of the subducting Philippines plate interface beneath the populated Tokyo region resulted in much more damage than other events in Japan's seismic history. In fact, despite being well-constrained by Slab 2.0 and regional models, interface proximity to the exposed population is often overlooked, and we emphasize this point via basic comparative subductology—that is, by comparing subduction zone characteristics worldwide. We do so first qualitatively by visual geometric comparisons and then quantitatively using ShakeMap and PAGER to compare shaking intensity and losses for significant cities above subduction zones worldwide. Though there are large uncertainties in several aspects of the hazard problem—such as seismogenic rupture extents, radiation complexity, and basin amplification—others are relatively well-constrained, including the potential source geometry. On the loss estimation side, there are also significant uncertainties, such as limited building inventories and fragilities, yet we can characterize the exposed population and overall vulnerabilities reasonably well. We show that once shaking is well-constrained via its source geometry, PAGER models perform well enough to infer and compare losses for future events. The central theme of this presentation is that source geometry and population, two well-characterized features of the loss estimation challenge, are well-known and critical diagnostics for future loss estimates via scenario realizations.

Session: Regional-Scale Hazard, Risk and Loss Assessments - II

Type: Oral

Date: 5/2/2024

Presentation Time: 03:00 PM (local time)

Presenting Author: David

Student Presenter: No

Invited Presentation: 

Authors