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Observations on Explosion-Triggered Seismic Events via Fiber Optic Sensing at Small Scales

Description: 

We present an aftershock analysis on seismic events recorded by distributed acoustic sensing (DAS) fiber following a series of chemical explosive experiments at the Blue Canyon Dome (BCD) on the grounds of the Energetic Materials and Testing Center (EMRTC) located approximately 6 km west of Socorro, NM. These experiments were a series of eight identical small (~4.5 MJ) chemical explosive sources detonated in a borehole at different depths (< ~55 m) and emplacement conditions, ranging from virgin rock to areas of varied a priori subsurface damage. We additionally performed each experiment both with and without filling the borehole with water. Here, we investigate both the presence of aftershocks induced by explosive sources on the DAS fiber data and characteristic differences in the aftershock sequences resulting from different emplacement conditions. Both the number of aftershocks and their distributions in time and space may provide information regarding how chemical explosive sources’ thermochemical energies are spent and converted to seismic waves.

DAS provides much higher spatial sampling density than traditional sensing methods, capturing seismic wavefields with considerably greater coverage and enabling detection of smaller events at close-in distances through trace-to-trace correlation. We visually detect aftershocks on the fiber waveforms for each chemical explosive source. Our apparent seismic velocity estimations find seismic velocities consistent with the rock velocities in the study area suggesting that the detected events are real aftershocks. Moreover, the explosion-triggered aftershocks follow Omori’s decay law for wet explosive sources but results are less clear for dry sources. Observations of aftershocks from the experiments at BCD demonstrate the utility of DAS to contribute to our understanding of explosion-induced aftershocks.

SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.

Session: Advancements in Forensic Seismology and Explosion Monitoring [Poster Session]

Type: Poster

Date: 5/2/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Gungor

Student Presenter: No

Invited Presentation: 

Authors