Abstract
SUMMARYWe present a new approach to simulate high-frequency seismic wave propagation in and under the oceans. Based upon AxiSEM3D, this method supports a fluid ocean layer, with associated water-depth phases and seafloor topography (bathymetry). The computational efficiency and flexibility of this formulation means that high-frequency calculations may be carried out with relatively light computational loads. A validation of the fluid ocean implementation is shown, as is an evaluation of the oft-used ocean loading formulation, which we find breaks down at longer periods than was previously believed. An initial consideration of the effects of seafloor bathymetry on seismic wave propagation is also given, wherein we find that the surface waveforms are significantly modified in both amplitude and duration. When compared to observed data from isolated island stations in the Pacific, synthetics which include a global ocean and seafloor topography appear to more closely match the observed waveform features than synthetics generated from a model with topography on the solid surface alone. We envisage that such a method will be of use in understanding the new and exciting ocean-bottom and floating seismometer data sets now being regularly collected.
Highlights
Oceans cover more than 70% of the Earth’s surface, and have complex and nuanced effects on the propagation of seismic waves through the planet
We present an animated comparison of the differences between the wavefields recorded at the seafloor in the case of the global fluid ocean with bathymetry and without bathymetry; with a focus source-time function and bandpass filtered at 5 s
We investigate whether the modifications to the waveforms induced by the addition of a fluid ocean and bathymetry are noticeable in observations
Summary
Oceans cover more than 70% of the Earth’s surface, and have complex and nuanced effects on the propagation of seismic waves through the planet. With the exception of isolated stations on remote islands, global seismometer distribution is enormously skewed toward being continent-based and so biased toward the northern hemisphere. Seismology in an oceanic context has been somewhat neglected as compared to its land-based counterpart, and the lack of comparably high-quality global data coverage from south of the Equator can be an impediment to seismic studies. As a consequence there are many large datasets which are in need of interpretation. Their complexity is such that observation alone is unlikely to prove a route to thoroughly understanding them; instead, we must make use of the synergy between observation and forward modelling
Sign-in/Register to view highlights & summary 
Submitted Version (
Free)
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call