Yield Estimation of the August 2020 Beirut Explosion by Using Physics‐Based Propagation Simulations of Regional Infrasound

Abstract

The August 2020 Beirut explosion is the largest single‐fired ammonium nitrate explosion documented in history. The massive explosion excited loud infrasound in the atmosphere, and clear waveforms were recorded by a regional infrasound array at an epicentral distance of 100 km, allowing for accurate measurements of explosion energy. We estimate the explosion size based on the infrasound waveform inversion. Unlike conventional inversions using empirical models, we perform full 3‐D finite‐difference simulations to obtain a physics‐based propagation model for the inversion. Accurate numerical modeling of infrasound is challenging as the propagation is substantially affected by the turbulent atmosphere. Instead of a single deterministic prediction, we provide a range of waveform predictions by running multiple simulations with stochastic weather forecast models, which allows for comprehensive uncertainty analysis of numerical modeling and estimated yields. Finally, we expand the yield estimation technique for seismoacoustic analysis and demonstrate the substantial advantage of the joint approach.

Examining Infrasound Propagation at High Spatial Resolution Using a Nodal Seismic Array

“…Additionally, the spatiotemporal resolution of available products is often inadequate. One approach to accounting for uncertainty in global‐scale atmospheric models is to realistically perturb individual profiles and run simulations using the perturbed parameters (Smets et al., 2015; Hupe et al., 2019; Perttu et al., 2020; Witsil et al., 2022; K. Kim & Pasyanos, 2022). However, on smaller spatial scales—such as the domain we consider in this work—higher‐spatial‐resolution models are required.…”

“…However, such simulations become prohibitively computationally costly for larger domains and higher source frequencies. This is the case even for situations where extensive computational resources are available, such as in K. Kim and Pasyanos (2022) where the source frequency was limited to below 0.9 Hz despite the presence of higher‐frequency energy. 2D simulations are much less costly than 3D simulations, but they cannot capture potentially important effects of variable crosswinds and wavefront interaction with out‐of‐plane topography (Blom, 2020).…”

“…However, there exists an intermediate source–receiver distance zone where neither atmospheric nor topographic propagation effects can be neglected (Lacanna et al., 2014). This intermediate zone poses a challenge to infrasound propagation modeling: it is computationally expensive to numerically simulate 3D infrasound propagation over topography in these relatively large domains (K. Kim & Pasyanos, 2022), and existing atmospheric specifications commonly used in propagation modeling schemes do not capture the smaller‐scale complexities of the temperature and wind fields (K. Kim & Rodgers, 2017).…”

Retrieving Seismic Source Characteristics Using Seismic and Infrasound Data: The 2020 ML 4.1 Kiruna Minequake, Sweden

“…Only sources at depths shallower than a wavelength excite evanescent seismic body waves that couple to the atmosphere as strong spherically propagating infrasound (Godin, 2011). In recent studies, remote seismically induced infrasound observations from explosive sources have been shown to provide unique insights into seismic parameters such as source depth (Averbuch et al., 2020; Lai et al., 2021) and yield (Kim & Pasyanos, 2022). Yet, due to the lack of high‐quality local and regional data, there is a need for additional rupture mechanism studies based on epicentral infrasound.…”