Workflow for computing time dependent seismic representations (force, torque, moment tensor) from numerical simulations

Overview

This is the code package and data accompanying the publication of Nonsymmetric seismic moment tensors and seismic torques: Theory and application to caldera collapse earthquakes at Kilauea Volcano in 2018, on the journal Bulletin of the Seismological Society of America. The package contains the workflow for computing time-dependent seismic source representations (i.e. force, torque, and moment tensor) from displacement and tractions at the boundary of the source region. The package also contains the data necessary to compute the seismic representations of a basaltic caldera collapse earthquake, the dynamic rupture simulation of which was previously presented in Wang et al., 2024.

Structure of the files

The package contains 4 directories: analyses, data, functions, and utilities.

"Analyses" contains all the scripts that can be run without modifications.

In particular, cmp_chamber_rep.m or cmp_fault_rep.m can be adapted to compute source representations for any source of interest to the user. pt_src_wavefield.m can be adapted to compute the seismic wavefield at the surface, given time dependent force, moment, and torque. 

Analyses 

• cmp_chamber_rep.m

  Compute point seismic representation for magma chamber dynamics during a

  basaltic caldera collapse earthquake (force, moment & torque).

   
• cmp_fault_rep.m 
  Compute point seismic representation for ring fault dynamics during a
  basaltic caldera collapse earthquake (force, moment & torque).
• cmp_total_rep.m

  Compute the complete seismic representation of caldera collapse

  earthquakes (ring fault + chamber).

   
• checkRingFaultMT.m
  Demonstrate that the moment tensor decomposition for the ring fault, in
  terms of +ISO & vertical P-CLVD, can be explained by the internal deformation
  of the caldera block due to static pressurization of the magma chamber.
• pt_src_wavefield.m

  Compute the wavefield for the entire Kilauea summit due to caldera collapse.

• cmpr_wavefields.m

  Compare the wavefield from dynamic rupture simulations of caldera collapse (SeisSol) with that from its point source representation (force, torque, moment).

• spheroid_fullspace_MT.m

           Verify the expression for the generalized moment tensor with uniformly pressurized  spheroidal cavities