Dynamics of an arc volcano with extruding lava domes, Merapi (Indonesia): from the magma reservoir to eruptive processes – DOMERAPI

The integrated DOMERAPI multidisciplinary scientific approach relies on a robust and novel combination of field and laboratory science as well as theoretically based modelling in the fields of geophysics, geochemistry and geology. This approach will overcome a number of scientific and technical challenges in several fields. State-of-the-art analytical methods are used to resolve the difficulties concerning quantifying the contribution mixing and crustal assimilation to pre-eruptive magma physico-chemical parameters. Furthermore, the controversial topic of the existence, nature and geometry of magma reservoirs under Merapi volcano is addressed by confronting results from different methods and new technical developments in petrology, high-pressure/temperature experiments, seismic tomography, GPS mesurements and gas flux measurements. The project proposes new analytical methodologies for imaging rock electrical properties (hydrothermal system). New technical developments in close partnership with Indonesian scientists will allow DOMERAPI to go beyond the challenges posed by installation and maintenance of a network of broadband seismometers, tiltmeters, electric sensors, UV spectrometers, and cameras in severe field conditions. The scientific analysis and crisis management of recent major eruptions has underscored the fundamental importance of magma flux time series. DOMERAPI is developping challenging methods for innovative stereophotogrammetric ground and satellite based data acquisition and analysis to be coupled with pyroclastic flow emplacement models enriched with new modules that consider high-impact turbulent pyroclastic density currents. Combining multiple datasets and interpretations in an integrative model of Merapi eruptive dynamics will be challenging. However, DOMERAPI’s unique multidisciplinary observational, analytical, experimental, and modelling framework will provide a unique corpus of new knowledge on eruptive dynamics of dome volcanoes.

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Borisova, A., Martel, C., Gouy, S., Pratomo, I., Sumarti, S., Toutain, J.P., Bindeman, I.N., de Pasival, P., Metaxian, J.-P., Surono, 2013. Highly explosive 2010Merapi eruption: evidence for shallow-level crustal assimilation and hybrid fluid. JVGR 261, 193–208.
Budi-Santoso, A., Lesage, P., Dwiyono, S., Sumarti, S., Subandriyo, J., Surono, Jousset, P., Metaxian, J.-P., 2013. Analysis of the seismic activity associated with the 2010 eruption of Merapi volcano, Java. JVGR 261, 153–170.
Jousset, P., Budi-Santoso, A., Jolly, A.D., Boichu, M., Surono, Dwiyono, S., Sumarti, S., Hidayati, S., Thierry, P., 2013. Signs of magma ascent in LP and VLP seismic events and link to degassing: an example from the 2010 explosive eruption at Merapi volcano, Indonesia. JVGR 261, 171–192.
Komorowski, J.C., Jenkins, S., Baxter, P.J., Picquout, A., Lavigne, F., Charbonnier, S., Gertisser, R., Cholik, N., Budi-Santoso, A., Surono, 2013. Paroxysmal dome explosion during the Merapi 2010 eruption: processes and facies relationships of associated high-energy pyroclastic density currents. JVGR 261, 260–294.

Volcanoes are complex systems that transfer magma from deep storage zones to the surface through a set of dykes and conduits. At each level, numerous coupled phenomena modify the chemical and physical properties of the magma and the state of the surrounding medium, producing geophysical and geochemical signals that may be detected at the surface. In the case of andesitic volcanoes, magma reaches the surface as lava flows, domes that may destabilize gravitationally or explosively to form nuées ardentes (pyroclastic flows) that travel many kilometers along the flanks of the volcano or via vertical explosive columns of fragmented magma. These different eruptive styles generate drastically different human, structural and environmental impact.

In order to improve our understanding of these magmatic processes and their interplay with eruptive dynamics, DOMERAPI project proposes a multi-disciplinary approach that involves and integrates petrological, geochemical and geophysical methods. This strategy is quite appropriate to understand complex dynamic systems where any individual technique would give only a narrow and limited perspective. DOMERAPI includes analysis of existing data, but also designs new and novel field observations and innovative laboratory experiments. As a major objective, results obtained by different disciplines will be integrated in numerical conduit flow models and interpreted in terms of physical processes, to assist in eruption forecasting and eruptive scenario definition on volcanoes forming lava domes.

This project is focused on Merapi, the most active volcano of Indonesia, a target relevant in the framework of the CNRS/INSU “site instrumenté” VELI (Volcans Explosifs Laboratoires Indonésiens) and scientifically exceptionally challenging after the paroxysmal eruption of October-November 2010. Such a project provides the opportunity to investigate the transition between moderate and violent explosions related to dome growth and collapse and the long-term impacts of such an event on dome-forming type volcanoes. To reach that goal, the permanent monitoring system must be implemented with a dense multiparametric network of sensors with cutting-edge technology, making Merapi one of the best monitored volcanoes in the world. The results will have major implications for understanding magmatic processes, volcanoe monitoring, hazard assessment and risk reduction on other explosive island-arc volcanoes, such as the French volcanoes in the West Indies.

This cooperative project brings together Indonesian and French research teams that are highly specialized in their own field, such as in volcano monitoring, experimental petrology, physical volcanology, geophysical structure imaging or numerical modeling of magmatic processes. It involves the four main French laboratories in this domain, which will reinforce the cohesion of this community and the synergy between the different disciplines of volcanology, a necessary condition to impulse volcanological research beyond the current state of the art. Associated American and German researchers will bring their scientific and technical expertise to this international exciting project. The partners are engaged in a common effort to pool their data and skills with the major objective of proposing an integrative model of Merapi’s eruptive behavior, one of the world’s most dangerous and populated volcano.