Abstract Volcanic calderas are large depressions formed by the rapid collapse of overlying rock into a magma chamber during eruptions. We utilize Smoothed Particle Hydrodynamics (SPH), a continuum, meshfree numerical method, to study the 2018 caldera collapse at Kīlauea volcano in Hawaii. We model the emergence of localized and distributed inelastic deformation (shear bands) during the collapse and their relation to chamber depressurization‐induced crustal down‐sagging. The SPH method has various advantageous features, namely its ability to handle large deformations, its nonlocal properties, and its capacity to accommodate strain localization without additional enhancements to the method. We specify pressure boundary conditions along the chamber top to model depressurization of the chamber, using the pressure change time history for the 2018 event inferred from a combination of geodetic data and lava‐lake drainage. This includes non‐monotonic pressure changes associated with early partial collapse events. Our simulations help to bound the critical magma pressure that triggers collapse and provide insights into various features including the stress arching effect and the evolution and directionality of both slip planes and zones of localized deformation. Using an elastoplastic Drucker‐Prager constitutive model, we analyze the contribution of inelastic deformation before and after the initiation of collapse both adjacent to Kīlauea caldera and within the subsiding block, concluding that significant distributed plastic deformation occurs once collapse initiates. Mechanistic differences between the pressure‐driven collapses and the traditional displacement‐driven trapdoor‐problem collapse are explored.
Castillo et al. (Wed,) studied this question.