Seismic Ambient Noise: Application to Taiwanese Data
Journal
Noisy Oceans: Monitoring Seismic and Acoustic Signals in the Marine Environment
Pages
17
ISBN
9781119750925
Date Issued
2023-01-01
Author(s)
Abstract
This chapter explores the various nonearthquake noises recorded at Taiwan’s seismometric stations, utilizing land-based and ocean-bottom observations to examine their frequency and generation mechanisms. The primary source of microseisms for the Taiwan area is the dynamic sea, with short-period microseisms regularly originating from the Taiwan Strait. Moreover, annual intense ocean storms expand the ambient noise’s frequency range to include longer-period microseisms. These longer-period microseisms are typically generated in shallow water and can be attributed to energetic events like typhoons and ocean swells. In addition to shallow-water noise, internal waves generate noise detected by deep-sea seismic stations (ocean-bottom seismometers [OBSs]). OBS records from southeast Taiwan reveal water advection caused by deep-sea internal waves, affecting the seafloor stations. Furthermore, OBSs in gas-hydrate-rich areas record burst-type short-duration events (SDEs) characterized by rapid vibrations (~4–8 Hz) and exponential decay, indicating seafloor fluid emissions. This chapter quantifies SDEs to pinpoint seafloor fluid conduits’ locations. In summary, the research highlights that ambient seismic noise is not solely linked to ocean surface waves but also stems from geological processes and converted ocean waves in the deep sea. This information is valuable for probing deep-sea environments using ambient seismic noise as a proxy.
Type
book part