Multi-Phase Seismic Sources of Tropical Cyclones

Session: Environmental and Near Surface Seismology: From Glaciers and Rivers to Engineered Structures and Beyond
Type: Oral
Date: 4/29/2020
Time: 08:30 AM
Room: 110 + 140
Description: 

The coupling between the ocean activity driven by wind and the solid earth generates seismic signals recorded by seismometers worldwide. In the 2-10 s period band, these signals represent the largest amount of the background seismic vibration of the Earth, called secondary microseisms. Pioneering work in the mid-twentieth century laid the foundation for our understanding of secondary microseisms generation by tropical cyclones. However, tracking their sources and linking them to the physical mechanisms behind the generation of these signals remain challenging, especially regarding shear (SH) waves.

Using an adapted back-projection method, we retrieve the seismic sources of P waves associated with Typhoon Ioke (2006) in the entire secondary microseism period band (T = 2–9 s) and along its entire life cycle. We also assess and compare the seismic sources of P, SV and SH waves associated with typhoon Ioke during its extratropical transition. To understand their generation mechanisms, we compare the observed multi-phase sources with theoretical sources computed with a numerical ocean wave model, and we assess the influence of the ocean resonance (or ocean site effect) and coastal reflection of ocean waves. This study provides new clues on the generation of body waves due to atmospheric-oceanic events and it can be seen as a first step towards using those events for imaging the Earth's interior.

Presenting Author: Lucia Gualtieri

Authors