HR: 0800h
AN: V11B-1434    [Abstracts]
TI: Duration-amplitude distribution of volcanic tremor at Soufri\`{e}re Hills Volcano, Montserrat
AU: Jolly, A
EM: ajolly@hawaii.edu
AF: Montserrat Volcano Observatory, Fleming's Monserrat West Indies, Montserrat, WI Montserrat
AU: Sturton, S
EM: sturton@min.uni-muenchen.de
AF: Depatment fuer Geo und Umweltwissenschaften, Theresienstrasse 41/111, Muenchen, 80333 Germany
AU: * Dingwell, D
EM: Dingwell@lmu.de
AF: Depatment fuer Geo und Umweltwissenschaften, Theresienstrasse 41/111, Muenchen, 80333 Germany
AB: The duration amplitude distribution is examined for volcanic tremor occurring at Soufriere Hills Volcano, Montserrat. A period of tremor data from 2004 is considered. On the 3rd March 2004 there was a small collapse and explosion event lasting about 10$\,\rm$min. Low level continuous tremor started on the 10th March, increasing on the 15th March when it was accompanied with vigorous ash venting which continued for three days. The tremor continued at moderate to high levels with some banding until the 3rd April when the first spasmodic tremor was seen. The spasmodic tremor changes amplitude very rapidly and occurred for periods of about 24 hrs interspersed with periods of more continuous episodes, until 7th May when the tremor died away. The RSAM amplitudes derived from the broadband seismic records are used to analyse the distributions of the amplitude. During the two month period the duration-amplitude distribution is observed to change from an exponential distribution to a normal distribution. The exponential distribution results from a scale bound source for which either the driving force or source geometry is constant. For a normal distribution both the source geometry and the driving force must be constant. These results provide a constraint on models of source mechanisms of tremor.
DE: 8400 VOLCANOLOGY
DE: 8419 Eruption monitoring (7280)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting