HR: 0800h
AN: S11A-1011    [Abstracts]
TI: Seismic Signals Associated with Landslides and with Tsunami at Stromboli Volcano, Italy
AU: Del Pezzo, E
EM: delpezzo@ov.ingv.it
AF: Osservatorio Vesuviano - INGV, Via Diocleziano 328, Napoli, 80124 Italy
AU: * La Rocca, M
EM: mlarocca@ov.ingv.it
AF: Osservatorio Vesuviano - INGV, Via Diocleziano 328, Napoli, 80124 Italy
AU: Tinti, S
EM: steve@ibogfs.df.unibo.it
AF: Dipartimento di Fisica, University of Bologna, Viale Berti Pichat 8, Bologna, 40127 Italy
AU: Saccorotti, G
EM: gilberto@ov.ingv.it
AF: Osservatorio Vesuviano - INGV, Via Diocleziano 328, Napoli, 80124 Italy
AU: Galluzzo, D
EM: galluzzo@ov.ingv.it
AF: Osservatorio Vesuviano - INGV, Via Diocleziano 328, Napoli, 80124 Italy
AB: The seismic signals produced by two landslides that occurred at Stromboli volcano on December 30, 2002, recorded by broadband seismic stations, have been analyzed. For both landslides, the characteristics of the low-frequency seismograms indicate a complex time-history in the release of seismic energy. The first landslide occurred over the submerged part of the NW sector of the volcano, and had associated a large-amplitude, low-frequency pulse representative of the abrupt detachment of a large mass. The highest amplitude low frequency signals are well described by a single-force source model. The second mass-failure episode is characterized by a complex source and can be interpreted as a multiple event, with less abrupt onset and at least four detachments occurring during 4-5 minutes. Synthetic seismograms generated by a shallow single force located in the submerged area of Sciara del Fuoco and directed upslope, fit well the first low frequency seismic pulse recorded at Stromboli and Panarea. From this simulation we estimated the force exerted by the first mass failure. The estimate of the volume through two different procedures, gives values in the range 1.0 - 1.5 million cubic meters and about 14 million cubic meters respectively. The landslides produced a tsunami that struck the coast of Stromboli island and reached in a few minutes the other islands of the Aeolian archipelago. Three broadband seismic stations installed on land about hundred meters from the coastline at Panarea island, located 20 km SW of Stromboli, recorded very long period seismic signals produced by the tsunami waves. Synthetic tsunami waves, obtained by a landslide source model and taking into account the bathymetry of the sea surrounding Stromboli and Panarea islands, fit well the observed phenomena and the experimental data. The ground tilt estimated by the broad band recordings is in good agreement with the expected value, given the distance of the station from the sea and the tsunami wave height.
DE: 7280 Volcano seismology (8419)
DE: 7299 General or miscellaneous
DE: 7209 Earthquake dynamics and mechanics
SC: Seismology [S]
MN: 2004 AGU Fall Meeting