Modeling explosive eruption dynamics and hazards: achievements and future challenges

Abstract:

About 1500 volcanoes are considered active worldwide, with about 600 having erupted in historical time. About 10% of the world's population live within 100 km of an historically-active volcano, and the potential for great loss of life and economic disruption in violent eruptions has emerged as a major problem. Developing the capacities to better understand volcano dynamics and to forecast and mitigate hazards are therefore principal scientific priorities.

This presentation gives an overview of some contributions to these goals arising in the last few decades, from the development, improvement, and application of physical-mathematical models. First, 1D steady-state homogeneous flow models were developed to identify the main mechanisms controlling volcanic explosive processes. Then, transient, 2D/3D, and multiphase (particles plus gas) flow models were developed implementing state-of-the-art formulations of the physics with high-performance computational techniques. I show that numerical simulations produced by such codes have been able to better understand and fairly accurately reproduce well-documented volcanic events, and provide key insights in comprehending the complex and often non-intuitive dynamics of explosive eruptions - such as conduit flow, convective plumes, collapsing columns, pyroclastic density currents, short-lived explosions, ash dispersal and deposition, etc. In particular, 3D modeling with DEM topography is a powerful tool in quantifying potential eruptive scenarios and associated hazards. Simplified flow models combined with Monte Carlo and statistical methods have also proved useful to produce quantitative probabilistic hazard maps at different space and time scales. The uncertainty effects displayed on such hazard maps offer more realistic characterization of hazards, and aid effectiveness of risk management strategies.

In the presentation I will develop selected modeling approaches, and illustrate numerical simulations of explosive phenomena specifically developed to quantify hazard at certain high-risk volcanoes, in Italy (Vesuvius, Campi Flegrei), the Caribbean (Montserrat, Guadeloupe), and Mt. St Helens (USA). I conclude by reporting on challenges for progress in modeling research, and in contributions to mitigation of volcanic emergencies.