Assessing Explosions at Regional Scales Using Small Seismic Arrays

Session: Explosion Seismology Advances
Type: Oral
Date: 4/29/2020
Time: 02:30 PM
Room: 240
Description: 

One of the major challenges in explosion monitoring is assessing small events, or so-called low-yield explosions with yields in the one kiloton range or even smaller. We expect such explosions from clandestine nuclear tests and tactical nuclear weapons, as well as acts of terror and industrial accidents. Unlike large explosions with a clear global signature, in most monitoring scenarios low-yield explosions will produce seismic signatures that are close to, or even below, the level of background seismic noise. Under these circumstances, noise should be expected to contaminate all aspects of seismic analysis. In this study, we examine the performance of seismic array analysis for low signal-to-noise records. Our data set consists of several years of ground-truthed explosions from a gold mining operation in central Alaska. We measure standard array parameters using three five-element seismic arrays azimuthally distributed from the source at distances of 300 to 350 km. For many parts of the world, this distance probably represents a best-case scenario for proximal seismic recording. We use these observations to assess the real-world uncertainty of such measurements. We characterize the error distributions and the impact of signal frequency. The three different arrays also offer evidence for the variability that should be expected across different geologies. Lastly, we comb the highly-variable population of mine blast sources to determine whether certain types of sources are inherently more amenable to array analysis. Our goal is to provide some expectation of performance for small seismic arrays at regional scales.

Presenting Author: Michael E. West

Authors