Publication Date:
2017-04-04
Description:
In the present paper we describe the results of a seismic field survey carried out at Copahue Volcano, Southern
Andes, Argentina, using a small-aperture, dense seismic antenna. Copahue Volcano is an active volcano that
exhibited a few phreatic eruptions in the last 20 years. The aim of this experiment was to record and classify
the background seismic activity of this volcanic area, and locate the sources of local earthquakes and volcanic
tremor. Data consist of several volcano-tectonic (VT) earthquakes, and many samples of back-ground seismic
noise. We use both ordinary spectral, and multi-spectral techniques to measure the spectral content, and an
array technique [Zero Lag Cross Correlation technique] to measure the back-azimuth and apparent slowness of
the signals propagating across the array.We locate VT earthquakes using a procedure based on the estimate of
slowness vector components and S–P time. VT events are located mainly along the border of the Caviahue
caldera lake, positioned at the South-East of Copahue volcano, in a depth interval of 1–3 kmbelow the surface.
The background noise shows the presence of many transients with high correlation among the array stations
in the frequency band centered at 2.5 Hz. These transients are superimposed to an uncorrelated background
seismic signal. Array solutions for these transients show a predominant slowness vector pointing to the
exploited geothermal field of “Las Maquinitas” and “Copahue Village”, located about 6 km north of the array
site. We interpret this coherent signal as a tremor generated by the activity of the geothermal field.
Description:
Published
Description:
284–294
Description:
3.1. Fisica dei terremoti
Description:
JCR Journal
Description:
reserved
Keywords:
volcanic seismicity
;
volcanic tremor
;
seismic array
;
volcano tectonic earthquakes
;
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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