HR: 0830h
AN: V51J-0410    [PDF]
TI: CALIPSO Borehole Station Observations Before and During the July 2003 Montserrat Eruption
AU: * Shalev, E
EM: shalev@duke.edu
AF: Duke University, Earth and ocean Sci., Box 90227, Durham, NC 27708 United States
AU: Malin, P E
AF: Duke University, Earth and ocean Sci., Box 90227, Durham, NC 27708 United States
AU: Sacks, S
AF: Carnegie Inst. of Washington, DTM, Washington, DC 20015 United States
AU: Linde, A T
AF: Carnegie Inst. of Washington, DTM, Washington, DC 20015 United States
AU: Voight, B
AF: Penn State University, Dept. of Geosciences, University Park, PA 16802 United States
AU: Mattioli, G S
AF: University of Arkansas, Dept. of Geosciences, Fayetteville, AR 72701 United States
AU: Young, S R
AF: Penn State University, Dept. of Geosciences, University Park, PA 16802 United States
AU: Elsworth, D
AF: Penn State University, Dept. of Geosciences, University Park, PA 16802 United States
AU: Hidayat, D
AF: Penn State University, Dept. of Geosciences, University Park, PA 16802 United States
AB: The July 13 2003 eruption of the Soufriere Hills Volcano on the Island of Montserrat was recorded by the four borehole stations of the CALIPSO project. Each station was instrumented with a three-component seismometer, a Sacks-Evertson strainmeter, a tiltmeter, and a GPS recording unit. One borehole station was installed in December 2002 and the others in February 2003. The instruments were designed to record a full spectrum of earth movements from 500 Hz to yearly-type plate movements. The andesitic lava dome on Montserrat was growing without major collapse since July 2001. Several near surface seismic events that produced long period surface-wave seismic signals were recorded during the months before the July 2003 eruption. The anomalous sequence started about three days before the eruption with a large number of small seismic events with decreasing time interval between them until they blended together to form a volcanic tremor. Increased background seismic noise and large pyroclastic flows started about 18 hours before the eruption. The eruption itself was recorded by two seismometers and three strainmeters with ultra-long period signals dominating the strainmeter records. It is interesting to note that the peak short period signal recorded by the seismometer was about 10 minute before the peak of the ultra-long signal recorded by the strainmeter. A possible explanation for this delay is that the short-period seismometer recorded the large pyroclastic flows that expose the core of the dome, followed by a large magma movement and eruption as shown by the large ultra-long signal.
DE: 7280 Volcano seismology (8419)
DE: 8419 Eruption monitoring (7280)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting