Real-time source deformation modeling through GNSS permanent stations at Merapi volcano (Indonesia

Thursday, 18 December 2014
Francois Beauducel1, Aisyah Nurnaning2, Masato Iguchi3, Ahmad Ali Fahmi4, Made Agung Nandaka5, Sri Sumarti2, Subandriyo Subandriyo2 and Jean Philippe Metaxian4, (1)Institut de Physique du Globe de Paris, Paris, France, (2)CVGHM, Yogyakarta, Indonesia, (3)Sakurajima Volcanic Observatory, Kagoshima, Japan, (4)Institut de Recherche pour le Développement, Indonésie, Jakarta, Indonesia, (5)Center of Volcanology and Geological Hazard Mitigation, BPPTKG, Bandung, Indonesia
Mt. Merapi (Java, Indonesia) is one of the most active and dangerous volcano in the world. A first GPS repetition network was setup and periodically measured since 1993, allowing detecting a deep magma reservoir, quantifying magma flux in conduit and identifying shallow discontinuities around the former crater (Beauducel and Cornet, 1999;Beauducel et al., 2000, 2006). After the 2010 centennial eruption, when this network was almost completely destroyed, Indonesian and Japanese teams installed a new continuous GPS network for monitoring purpose (Iguchi et al., 2011), consisting of 3 stations located at the volcano flanks, plus a reference station at the Yogyakarta Observatory (BPPTKG).

In the framework of DOMERAPI project (2013-2016) we have completed this network with 5 additional stations, which are located on the summit area and volcano surrounding. The new stations are 1-Hz sampling, GNSS (GPS + GLONASS) receivers, and near real-time data streaming to the Observatory. An automatic processing has been developed and included in the WEBOBS system (Beauducel et al., 2010) based on GIPSY software computing precise daily moving solutions every hour, and for different time scales (2 months, 1 and 5 years), time series and velocity vectors. A real-time source modeling estimation has also been implemented. It uses the depth-varying point source solution (Mogi, 1958; Williams and Wadge, 1998) in a systematic inverse problem model exploration that displays location, volume variation and 3-D probability map.

The operational system should be able to better detect and estimate the location and volume variations of possible magma sources, and to follow magma transfer towards the surface. This should help monitoring and contribute to decision making during future unrest or eruption.