A prediction of the longevity of the Lusi mud eruption, Indonesia

A mud eruption, nicknamed Lusi, began near Sidoarjo, East Java, in May 2006. It has discharged ∼ 10 4–10 5 m 3/day of mud ever since. In order to understand the nature of the eruption and its potential longevity, we develop a model for the coupled evolution of the mud source and ascent of mud through a conduit to the surface. The ascent of the mud is driven by overpressure in the mud source and by the exsolution and expansion of dissolved gasses. We assume that erupted fluids originate in the mud source region. Mobilization of the mud is caused by elastic stresses induced by mud evacuation from the subsurface. We perform Monte Carlo simulations to explore model outcomes while perturbing the unknown material properties of the mud and surrounding medium. Using our preferred model, we calculate a 50% chance of the eruption lasting < 41 yrs and a 33% chance that it lasts > 84 yrs. Eruptions often end with the formation of a caldera, but longer eruptions are less likely to form a caldera. Model predictions can be refined with additional, but currently unavailable constraints: more precise estimates of mud discharge, the yielding behavior of the materials in the subsurface, total gas content in the mud source, and identification of any erupted fluids that do not originate in the mud source. ► We develop a mechanical model for the ‘Lusi’ mud eruption, Indonesia. ► Our model incorporates a new way of looking at mud reservoirs. ► Caldera formation is one possible model outcome. ► We predict a 50% chance that the eruption will last less than 40 yrs.