Thunderquakes by Fiber-Optic Distributed Acoustic Sensing Array

Session: Environmental and Near Surface Seismology: From Glaciers and Rivers to Engineered Structures and Beyond
Type: Oral
Date: 4/29/2020
Time: 09:00 AM
Room: 110 + 140
Description: 

A distributed acoustic sensing (DAS) array using pre-existing underground fiber-optics beneath the Penn State campus is demonstrated to characterize thunder-induced ground motions. The DAS array is part of the Fiber Optic foR Environmental SEnsEing (FORESEE) project on the Penn State campus. During 03:20 – 03:50 UTC on 15 April 2019 in State College, PA, we identify 18 thunder events associated with lightning strikes in the DAS array data. The high fidelity DAS data appears very broadband, and their peak frequency ranges from 20 to 130 Hz. We analyze these dense arrival time measurements to determine horizontal phase velocity and back azimuth using a time-domain grid search using dense arrival time measurements. We then invert for the source location and its origin time using a least-square inversion. Taking advantage of high-density sensors, we also conduct full waveform modeling and time-reversal source imaging analysis of the thunder waveforms. The movement of thunder sources from the northwest to the southeast and the inverted thunder locations are verified with locations from the National Lightning Detection Network (NLDN). We also found that thunder signal power recorded by DAS is positively correlated with NLDN lightning current power. These findings indicate that fiber-optic DAS observations of thunderquakes offer a new avenue of studying thunderquakes and weather events thunderstorms.

Presenting Author: Tieyuan Zhu

Authors