Publication Date:
2022-03-13
Description:
Short duration events (SDEs) are reported worldwide from ocean-bottom seismometers
(OBSs). Due to their high frequency (4–30 Hz) and short duration, they are commonly
attributed to aseismic sources, such as fluid migration related processes from cold seeps,
biological signals, or noise. We present the results of a passive seismic experiment that
deployed an OBS network for 10-month (October 2015–July 2016) at an active seepage
site on Vestnesa Ridge, West Svalbard continental margin.We characterize SDEs and their
temporal occurrence using the conventional short-time-average over long-time-average
approach. Signal periodograms show that SDEs have periodic patterns related to solar
and lunar cycles. A monthly correlation between SDE occurrences and modelled tides for
the area indicates that tides have a partial control on SDEs recorded over 10 months. The
numbers of SDEs increase close to the tidal minima and maxima, although a correlation
with tidal highs appears more robust. Large bursts of SDEs are separated by interim quiet
cycles. In contrast, the periodicity analysis of tremors shows a different pattern, likely
caused by the effect of tidally controlled underwater currents on the instrumentation. We
suggest that SDEs at Vestnesa Ridge may be related to the dynamics of the methane
seepage system which is characterized by a complex interaction between migration of
deep sourced fluids, gas hydrate formation and seafloor gas advection through cracks.
Our observation from this investigated area offshore west-Svalbard, is in line with the
documentation of SDEs from other continental margins, where micro-seismicity and gas
release into the water column are seemingly connected.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
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isiRev
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