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Thermal-hydrologic mechanism for rainfall-triggered collapse of lava domes

¹ College of Earth and Mineral Sciences, Pennsylvania State University, University Park, Pennsylvania 16802-5000, USA
² British Geological Survey, Keyworth, Nottingham NG12 5GG, UK
³ College of Earth and Mineral Sciences, Pennsylvania State University, University Park, Pennsylvania 16802-5000, USA

Hazardous gravitational collapses involving hot lava domes can be triggered by intense rainfall, both in periods of active dome growth and volcanic repose. The collapses can evolve into energetic failures involving as much as 90% of the dome, or >100 x 10⁶ m³ of dome lava, retrogressively removed over several hours. Understanding such potentially lethal phenomena is vital, but traditional explanations for rain-induced slope failure are problematic for rainfall on hot (typically >400 °C) crystalline lava. In this paper we quantitatively develop a new thermal-hydrologic mechanism that can cause such failures: pressure buildup within fissures due to effusive gas trapped by a rain-saturated dome carapace results in increased destabilizing forces and the loss of mass strength, and ultimately results in failure of the dome. Our mechanistic models are consistent with field observations and provide a quantification of threshold rainfall intensities and durations required to trigger failure.

Key Words: lava dome • rainfall • instability • pyroclastic flows • hazard

This article has been cited by other articles:

				J. D. Webster and C. W. Mandeville Fluid Immiscibility in Volcanic Environments Reviews in Mineralogy and Geochemistry, July 1, 2007; 65(1): 313 - 362. [Full Text] [PDF]