HR: 1330h
AN: V52B-0429    [PDF]
TI: Long-Period and Very-Long-Period Seismicity Associated with Lava Extrusions and Volcanic Degassing at Popocatepetl Volcano, Mexico
AU: * Arciniega, A
EM: aarciniega@usgs.gov
AF: US Geological Survey, 345 Middlefield Rd. MS-910, Menlo Park, CA 94025 United States
AU: * Arciniega, A
EM: aarciniega@usgs.gov
AF: Institute of Geophysics, UNAM, Cd Universitaria, Mexico City, 04510 Mexico
AU: Chouet, B
EM: chouet@usgs.gov
AF: US Geological Survey, 345 Middlefield Rd. MS-910, Menlo Park, CA 94025 United States
AU: Dawson, P
EM: dawson@usgs.gov
AF: US Geological Survey, 345 Middlefield Rd. MS-910, Menlo Park, CA 94025 United States
AU: Asch, G
AF: GeoForschungsZentrum, Telegrafenberg, Potsdam, D-14473 Germany
AU: Dietel, C
AF: US Geological Survey, 345 Middlefield Rd. MS-910, Menlo Park, CA 94025 United States
AB: From November 1999 through July 2000 a broadband seismic experiment was carried out at Popocatepetl Volcano as part of an international cooperative program between the GeoForschungsZentrum in Potsdam, Germany, the U.S. Geological Survey, and the Institute of Geophysics at UNAM, Mexico. The goal of this experiment was to record seismic activity at Popocatepetl over a wide period range (0.04 to 100 s). The network deployed included 15 stations distributed along radial profiles on the upper flanks of Popocatepetl, and 7 stations at lower elevations on the volcano's western flank. All significant vulcanian events were well recorded by our network. Volcanic activity during the experiment was characterized by emissions of gas and ash, and by the formation of a lava dome within the summit crater. Ash emissions ranged from small short-lived plumes rising a few hundred meters above the crater rim, to larger plumes reaching up to 5 km above the crater. Resulting tephra falls dusted the entire summit area. Bursts of volcanic degassing were accompanied by long-period (LP) seismic signals observed as isolated events, or as sequences of discrete events with overall durations comparable to those of visible activity documented by video. Some gas emissions were accompanied by persistent or spasmodic tremor. LP events and tremor episodes increased in frequency and intensity in early February 2000. Individual LP signals, tremor, and swarms of hybrid events were frequently observed during intervals of active dome growth. Very-long-period (VLP) signals accompanying degassing activity were also clearly recorded at stations closest to the crater. The VLP signals exhibit quasi-identical pulse shapes with periods near 25 s from event to event. VLP signals with periods near 30 s and VLP tremor with periods in the range 15-22 s, lasting 20 min or more, clearly correlated with vulcanian processes. Preliminary locations of LP events based on phase picks, and particle-motion analyses of VLP pulses, consistently constrain shallow seismic sources within the uppermost 1000 m below the crater floor.
DE: 7280 Volcano seismology (8419)
DE: 8400 VOLCANOLOGY
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting