Publication Date:
2017-04-04
Description:
We have investigated thewavefield properties of the seismic signals generated by the explosions
of Volc´an de Colima (M´exico). We have analysed these properties to understand the initial
mechanism that triggered the explosive events. Our study is focused on the direct waves
coming from the crater area. Thus, we have analysed a set of moderate volcanic explosions
at Volc´an de Colima that was recorded by a small aperture seismic array over two periods:
October 2005 and April 2006. We can distinguish two types of explosions, Vulcanian and
ash-free events. Both types of explosions share the same characteristics, that is a long-period
signal (not related to any type of emission) before the arrival of high frequency phases, and
a later high frequency signal directly related to ash or gas emission. We have applied the
Zero Lag Cross Correlation technique to obtain backazimuth and apparent slowness of the
incoming waves. We have also applied polarization analysis to the record of every detected
volcanic explosion. By comparing the results of both of these analyses, we have been able to
identify the dominant wave types that comprise the seismic wavefield and infer in time and
space a possible primary source mechanism that would trigger the volcanic explosions. We
have observed an apparent slowness variation of the first onset of the long-period (LP) signal
with a possible upward migration of the source; the depth of the source has been identified
at a range between 2.6 and 3.3 km below the crater, associated with the range of measured
apparent velocities relative to the first onset of the LP signal.
Description:
Published
Description:
1383–1398
Description:
3.1. Fisica dei terremoti
Description:
JCR Journal
Description:
reserved
Keywords:
Explosive volcanism;
;
Volcano monitoring.
;
04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
;
04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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