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Seismoacoustic Summary Analysis of the 2020 Beirut Explosion

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

Type: Oral

Date: 4/22/2021

Presentation Time: 02:15 PM Pacific

Description: 

We describe a summary analysis of the August 4, 2020 surface explosion in the Port of Beirut. The explosion involved ~2.75 kt of ammonium nitrate that was accidentally detonated. The event was detected by local, regional, and global seismic and infrasound stations and had unique signal characteristics. We made manual arrival picks and amplitude measurements on ocean-bottom and island seismic arrays and stations in the eastern Mediterranean as well as at stations out to ~3000 km where possible. We observed many unique signals at the stations and arrays and were able to use FK analysis to get azimuth and slowness measurements. Using the seismic arrival measurements, we utilize the event as ground-truth (GT) to test various seismic velocity models for location. Source spectra for the event were also obtained via propagation corrections, enabling an estimate of moment magnitudes (Mw) for several phases (Pg = 3.6, Lg = 3.3). Pg is more heavily excited by this source, and appears explosion-like. Using the Pg and Lg Mw range of 3.3-3.6, the yield estimate is ~1.0-2.75 kt. Infrasound analysis found 5 International Monitoring Stations detected signals plus the nearby IMA (Israeli) infrasound station. Infrasound signals were observed at distances up to 6000+ km and localization is biased northward. An infrasound signal yield estimate was made using a period-yield relationship. Peak infrasonic frequencies observed cover 0.14 – 0.19 Hz, and correspond to 0.8 – 2.0 kT equivalent TNT yield.

Presenting Author: Michael L. Begnaud

Student Presenter: No

Authors