Current Research in EEPS: Tieyuan Zhu, Penn State
Excitation of Seismic Waves by the Atmosphere: Observation and Cause of Thunderquakes
In this talk, I’ll show seismological observations of four thunderstorms through the spring and summer of 2019, as recorded by the distributed acoustic sensing (DAS) fiber optic array (4.9 km) beneath the Penn State campus in State College, PA. This is the first array of its kind deployed in a region which regularly experiences thunder and lightning during storms. The high fidelity DAS data shows that the thunder-induced seismics are very broadband, and their peak frequency ranges from 20 Hz to 130 Hz. With a dense sensor array in the local region, we are able to construct the seismic full waveform response of the thunderstorm events and track the wave propagation across the array. We use a time-domain gridsearch and modified Geiger’s method to obtain the back azimuth and slowness of the waves, and to pinpoint source locations of the thunderstorm signals. Correlated with the time of the recorded signal, this data allows reconstruction of thunderstorm movement, as well as offering some insight into subsurface velocity. We verify thunder-seismic sources with lightning locations from the National Lightning Detection Network (NLDN). Interestingly, we found that thunder-seismic power recorded by DAS is positively correlated with NLDN lightning current power. Finally, I’ll discuss our work in progress of studying thunderquakes: the possible mechanism of thunderstorm-induced quakes, characterizing the near surface velocity structure, and probing the thunder-ground coupling process.
Zoom Webinar Link: https://riceuniversity.zoom.us/j/97371800331?pwd=bEN0MDRLS3ZWWHUxTGVuakl6Zkpzdz09