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A Seismic Yield Estimate for the 2020 Beirut Explosion Using Full-Waveform Envelope Predictions and Calibrated Site and Path Models

Session: Analyses and Implications of the 4 August 2020 Beirut Explosion Series I

Type: Oral

Date: 4/22/2021

Presentation Time: 02:00 PM Pacific

Description: 

On August 4, 2020, a large chemical explosion occurred in a storage depot in the port of Beirut, Lebanon. A large network of local- and regional-distance seismic stations recorded waveforms from the explosion, which we analyzed to estimate seismic yield. We calculated a prompt diagnostic yield by applying a new full-waveform processing technique, which incorporates improved waveform envelope predictions that better account for the complexity in the direct-wave and early-coda P waves. Our initial analysis of the Beirut event indicated a seismic yield of 2.75 kt (0.44±0.39 in log10 kt) of TNT-equivalent at the free surface, which agrees reasonably well with published estimates of the explosive material stored at the detonation site. We achieved this ‘quick-look’ result in the absence of a priori information by utilizing a proxy one-dimensional path attenuation model and an average site correction.

In this study, we will present results from further characterization of the highly complex propagation effects in the local and regional recordings of the Beirut event. We will analyze an extensive earthquake dataset from the region to estimate optimal waveform envelopes and a propagation model that accounts for laterally varying attenuation structure. This analysis will produce a fully calibrated yield estimate that we will compare to our previous prompt results. We will then thoroughly analyze the uncertainties of seismic yields estimated with fast one-dimensional versus optimized two-dimensional path and site models, as well as the time it takes to generate each yield estimate. Our goal is to demonstrate that it is possible to create an automated framework for the calibration process and quickly obtain an optimized model in a new and uncalibrated region.

Presenting Author: Delaine Reiter

Student Presenter: No

Authors