SAR- and gravity change-based characterization of the distribution pattern of pyroclastic flow deposits at Mt. Merapi during the past 10 years

Autor: Asep Saepuloh, Ari Setiawan, Katsuaki Koike, Makoto Omura, Masato Iguchi
Rok vydání: 2009
Předmět:
Zdroj: Bulletin of Volcanology. 72:221-232
ISSN: 1432-0819
0258-8900
DOI: 10.1007/s00445-009-0310-x
Popis: Mt. Merapi, Indonesia, is one of the most active and dangerous volcanoes in the Torrid Zone. This volcano has erupted frequently and has produced pyroclastic flows following the collapse of the summit lava dome. We used Synthetic Aperture Radar (SAR) data acquired by JERS-1 and RADARSAT-1 satellites from April 1996 to July 2006 to clarify the distribution patterns of the pyroclastic flow deposits. The extent of the deposits, termed P-zones, was accurately extracted by ratio operation and low-level feature extraction from SAR intensity images. These images highlighted temporal changes of the distribution area, perimeter, flow distance, included angle, and collapse direction. To validate the image-processing results, reflectance spectra of the rock samples collected after the eruption in June 2006 were measured in a laboratory. The reflectance spectra of all samples showed similar characteristics to the reference spectra, which were derived from atmospheric correction of Hyperion sensor image data covering the lava dome at the summit. Therefore, P-zones were confirmed to be the pyroclastic flow deposits originating from destruction of the lava dome at the summit. The image-processing results clarified that the extent of the distribution areas, perimeter, flow distances, and included angle of the P-zones were variable among the eruptions, while the collapse direction had a constant pattern. The collapse pattern followed a clockwise change from the south toward the west. By comparing the ratio maps of Bouguer gravity anomaly data in two periods, the change was interpreted to originate from the inclination of the conduit and the formation of shallow and deep magma reservoirs.
Databáze: OpenAIRE
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