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Shallow S wave attenuation and actively degassing magma beneath Taal Volcano, Philippines
Author(s) -
Kumagai Hiroyuki,
Lacson Rudy,
Maeda Yuta,
Figueroa Melquiades S.,
Yamashina Tadashi
Publication year - 2014
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl061193
Subject(s) - geology , volcano , seismology , magma , attenuation , tectonics , geophysics , physics , optics
Taal Volcano, Philippines, is one of the world's most dangerous volcanoes given its history of explosive eruptions and its close proximity to populated areas. A real‐time broadband seismic network was recently deployed and has detected volcano‐tectonic events beneath Taal. Our source location analysis of these volcano‐tectonic events, using onset arrival times and high‐frequency seismic amplitudes, points to the existence of a region of strong attenuation near the ground surface beneath the east flank of Volcano Island in Taal Lake. This region is beneath the active fumarolic area and above sources of pressure contributing inflation and deflation, and it coincides with a region of high electrical conductivity. The high‐attenuation region matches that inferred from an active‐seismic survey conducted at Taal in 1993. These features strongly suggest that the high‐attenuation region represents an actively degassing magma body near the surface that has existed for more than 20 years.