Forschungs- & Entwicklungsinformationsdienst der Gemeinschaft - CORDIS

FP5

MULTIMO Berichtzusammenfassung

Project ID: EVG1-CT-2000-00021
Gefördert unter: FP5-EESD
Land: France

A model to localize deformations and earthquakes at Montserrat

In order to compare the locations of tilt and hybrid earthquakes that occurred simultaneously at Montserrat,

- A model for deformations:
A fully three-dimensional boundary element method for elastic medium is used to re-interpret the tilt cycles measured in 1997 at Montserrat. Assuming the source of tilts is located along a cylindrical conduit, we show that this source is located 900 meters depth below the dome summit. Scaling the conduit diameter so that the elastic rock matrix does not fail, the measured tilt amplitudes are explained by a conduit diameter larger than 100 meters. This size is larger than the 30 meter diameter estimated from petrological and geological observations, but it can be explained if the medium around the conduit is visco-plastic.

- A method to localize LPs at Montserrat was developed:
The weak impulsive onset of hybrid earthquakes poses a challenge to conventional arrival time location algorithms. Considering the waveform similarity of events within earthquake swarms on Montserrat, their location are constrained by picks obtained from stacked seismograms. Using a velocity structure derived from fitting the extensive catalogue of events from the ongoing eruption, the events associated with the deformations cycles are located at approximately 1250 meters below the dome summit.

Reported by

Université Blaise Pascal (Clermont-Ferrand II)
Rue Kessler 5
63038 Clermont-Ferrand Cedex
France
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