Hydro-Acoustic Monitoring on the Kamchatka Shelf: A Possibility of Early Location of Oceanic Earthquake and Local Tsunami Warning

Sasorova, E. V.; Левин, Б. В.; Morozov, V. E.; Didenkulov, I. N.

doi:10.1007/1-4020-3331-1_19

“…Additionally, as t-phases experience a reduced degree of geometric spreading (cylindrical, ∼ 1 r , rather than spherical, ∼ 1 r 2 ), they may offer greater sensitivity to more distant or smaller seismic events than would be obtained from the corresponding P or S waves at the same epicentral distance; furthermore, the lower and better-constrained sound speed in water can yield tighter constraints on source location than are possible from signals in the solid Earth alone (Dziak et al 2004). Other potential uses of hydroacoustic phases include early-warning systems for tsunamis (Sasorova et al (2005), ), acoustic thermometry for remote monitoring of long-term changes in ocean temperature (Dushaw et al 1999), detection of glacial and ice-calving events (Chapp et al 2005), as well as monitoring of cetacean populations (e.g. McDonald et al (1995), Dréo et al (2019)) and for illicit nuclear tests in violation of the Comprehensive Nuclear Test Ban Treaty (Mitchell (2002), Okal (2008)).…”

Section: Introductionmentioning

confidence: 99%

Oceanic high-frequency global seismic wave propagation with realistic bathymetry

Fernando

¹

,

Leng

²

,

Nissen‐Meyer

³

2020

Geophysical Journal International

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SUMMARY We 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.

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“…Additionally, as t-phases experience a reduced degree of geometric spreading (cylindrical, ∼ 1 r , rather than spherical, ∼ 1 r 2 ), they may offer greater sensitivity to more distant or smaller seismic events than would be obtained from the corresponding P or S waves at the same epicentral distance; furthermore, the lower and better-constrained sound speed in water can yield tighter constraints on source location than are possible from signals in the solid Earth alone (Dziak et al 2004). Other potential uses of hydroacoustic phases include early-warning systems for tsunamis (Sasorova et al (2005), ), acoustic thermometry for remote monitoring of long-term changes in ocean temperature (Dushaw et al 1999), detection of glacial and ice-calving events (Chapp et al 2005), as well as monitoring of cetacean populations (e.g. McDonald et al (1995), Dréo et al (2019)) and for illicit nuclear tests in violation of the Comprehensive Nuclear Test Ban Treaty (Mitchell (2002), Okal (2008)).…”

Section: Introductionmentioning

confidence: 99%

Oceanic high-frequency global seismic wave propagation with realistic bathymetry

Fernando¹,

Leng²,

Nissen‐Meyer³

2020

Preprint

2

5

0

View full text Add to dashboard Cite

We present a new approach to simulate high-frequency seismic wave propagation in and under the oceans. Based upon AxiSEM3D (Leng et al. 2019), this method sup- ports 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 datasets now being regularly collected.

show abstract