Publication Date:
2017-04-04
Description:
Crustal tectonic seismicity in the Southern Tyrrhenian Sea is characterized by the high occurrence rates of
earthquakes to the west of the alignment of Salina, Lipari and Vulcano islands in the Aeolian archipelago. Only a few
earthquakes affect the crustal region east of these islands, whereas intermediate and deep seismicity plays a relevant
role. Based on this evidence, two aspects of the seismic swarm recorded at the Aeolian Island Seismic Network
between June 6 and 17, 1999 looked anomalous. The first aspect concerned the number of earthquakes (78) that
affected the Stromboli submarine edifice in a short time interval. Secondly, despite the low maximum magnitude Md
3.2 reached, the cumulative strain release was conspicuous in comparison with previous swarms in this region. We
localized the swarm about 6 km northeast of Stromboli, at a depth between 8 and 12km. The source region was
identified using standard methods of hypocentral location, as well as azimuth analysis. It is worth noting that the
volcanic activity at Stromboli did not change significantly during the swarm nor throughout the following months.
Therefore, the seismic swarm had no link with volcanic activity observed at the surface. Most of the earthquakes
shared similar waveform and frequency content, and can be divided into families. We identified some earthquakes -
with magnitude up to Md 3 - having relatively low frequency content at different seismic stations. This anomalous
feature leads us to hypothesize the presence of fluid circulation and/or propagation of seismic waves in a ductile
medium. Our hypothesis is in agreement with studies on marine geology, which highlight various forms of submarine
volcanism in the southern basin of the Tyrrhenian Sea.
Description:
This work was financially supported by
the EC project MULTIMO (Contract No.
EVG1-CT-2000-00021).
Description:
Published
Description:
121-136
Description:
JCR Journal
Description:
reserved
Keywords:
Earthquakes
;
Seismic swarm
;
Volcanoes
;
Stromboli
;
04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
;
04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
