Oral Presentation

The utilization of the emerging distributed acoustic sensing (DAS) technique with pre-existing submarine fiber-optic cables in recent years has demonstrated itself a promising strategy to deploy cost-effective dense arrays on the seafloor and to reach long distances off the coast for long-term ocean bottom seismic monitoring. A variety of oceanic and seismic phenomena in the ocean bottom environment are now accessible with unprecedented detail for analysis, such as ocean gravity waves, low-frequency microseisms, as well as local and teleseismic earthquake signals, earthquake-based and ambient-noise-based Scholte waves, and ocean bottom fault zone illumination.

Here, we present a demonstration of our latest submarine DAS experiment at Monterey Bay using the DAS technique interrogating a 52-km-long submarine fiber-optic cable at full length. Besides observing ubiquitous ocean bottom dynamics, the cable runs across multiple fault zones on the seafloor that are well illuminated by seismic waves from local earthquakes, including the major San Gregorio fault zone that intersects the cable at ~37 km. Local shaking events are also detected with distinct features from regular earthquake signals, which are probably originated from the geologically active environment in the Monterey Canyon off the coastal continental shelf.