Analyzing noise properties of cabled broadband ocean-bottom seismometers for the application of smart sea cable in the Vanuatu - New Caledonia subduction zone

Abstract

The Vanuatu subduction zone (VSZ), also known as the New Hebrides Trench, is a tectonically active zone characterized by a high frequency of earthquakes with magnitudes greater than 5.5 and volcanic activity. Earthquakes with epicenters ranging from shallow (~10 km) to deep (~700 km) cluster beneath the VSZ, with limited opportunity for earthquake and tsunami early warnings. Recent initiatives aim to install geophysical and oceanographic monitoring equipment on a seafloor cable extending from New Caledonia to Vanuatu using Science Monitoring and Reliable Telecommunications (SMART) cable technology to mitigate these hazards. These oceanographic sensors would measure temperature, pressure, and seismic acceleration to monitor climate and ocean observations, sea-level changes, and provide reliable geophysical measurements of earthquakes and fault properties. However, seismic waves recorded by seafloor instruments may have tilt and compliance noise. Using the Automated Tilt and Compliance Removal (ATaCR) method, these noise properties are analyzed from broadband ocean bottom seismometers (BBOBS) from a similar cabled system, the Ocean Observatory Initiative offshore the Cascadia subduction zone, to establish a baseline for comparison with future SMART cable installations in subduction zones. Understanding these noise parameters, we can estimate the likely output signals from different instrument types at various water depths, for future designs such as those employed by the Vanuatu-New Caledonia’s TAMTAM SMART system.