How Low Can You Go? Source Analysis of Low Yield Chemical Explosions

Session: Explosion Seismology Advances
Type: Oral
Date: 4/29/2020
Time: 03:30 PM
Room: 240
Description: 

Lawrence Livermore National Laboratory conducted the second in a series of field experiments, known as FE2, at a site southeast of Livermore, California.  The experiment consisted of three near-surface chemical explosions of several tens of kilograms TNT-equivalent yield, which were well-recorded by a number of seismic and acoustic sensors installed within 2 km of the events.  Part of our investigation is performing a source analysis to estimate the yield and depth/height of these ground truth explosions.  While we have developed the local and regional envelope yield method to look at large buried (Pasyanos et al., 2012) and near-surface (Pasyanos and Ford, 2015) events, there are several additional challenges associated with these low yield explosions.  First and foremost is the need for investigation at frequencies much higher than for larger chemical or nuclear explosions.  Fundamental in this analysis are the calibrations of coda shape which are needed at these higher frequencies.  Another complication for these shallow sources at close distances is the interference of the acoustic signal on the seismic sensor.  We address this by the use of a normalized least-mean-squares (NLMS) adaptive filter on co-located acoustic sensors to remove the interfering signal.  We then combine our analysis using the cleaned seismic recordings with the corresponding analysis using the acoustic recordings to produce a joint seismo-acoustic estimate of yield for the three FE2 explosions.

Presenting Author: Michael E. Pasyanos

Authors