| Authors
R. Mellors, SDSU
D. Kilb, IGPP/SIO/UCSD
A. Aliyev, Geology Institute, Azerbaijan Academy of Sciences
A. Gasanov, Republic Center of Seismic Survey, Azerbaijan Academy of Sciences
G. Yetirmishli, Republic Center of Seismic Survey, Azerbaijan Academy of Sciences
Project
Description
We examine the potential triggering relationship between large earthquakes and methane mud volcano eruptions. Our dataset consist of a 191-year catalog (1810 to 2001) of eruptions from 77 volcanoes in Azerbaijan, Central Asia, supplemented with reports from mud volcano eruptions in Japan, Romania, Pakistan and the Andaman Islands. We compare of the occurrence of historical regional earthquakes (M > 5) with the occurrence of Azerbaijan mud volcano eruptions and find the number of same-day earthquake/eruption pairs is significantly higher than expected if the eruptions and earthquakes are independent Poisson processes. The temporal correlation between earthquakes and eruptions is most pronounced for nearby earthquakes (within ~100 km) that produce seismic intensities of Mercalli 6 or greater at the location of the mud volcano. This assumed magnitude/distance relationship for triggering observed in the Azerbaijan data is consistent with documented earthquake induced mud volcano eruptions elsewhere. We also find a weak correlation that heightened numbers of mud volcano eruptions occur within 1 year after large earthquakes. The distribution of yearly eruptions roughly approximates a Poisson process, although the repose times somewhat favor a non-homogenous failure rate, which implies that the volcanoes require some time after eruption to recharge. The volcanic triggering likely results from some aspect of the seismic wave's passage, but the precise mechanism remains unclear.
Figure Caption
Plot of distance versus magnitude for earthquakes and mud volcanoes. The small dots show all possible distance/magnitude pairs in our catalog (from each earthquake epicenter to a known mud volcano location even if it did not erupt). Open stars show Azerbaijan mud volcano locations that were reported to have eruptions on the same day as a large earthquake. Open circles were reported to show increased activity after the earthquakes in November/December 2000. Red filled stars show magnitude/distance for other reported earthquake/eruption triggering pairs. Approximate intensity bounds (dashed lines) are also shown. Note that intensity ~6 represents an approximate lower limit for triggering.
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