Mechanism of the 1996-97 non-eruptive volcano-tectonic earthquake swarm at Iliamna Volcano, Alaska

作者：Roman Diana C^*; Power John A

来源：Bulletin of Volcanology, 2011, 73(2): 143-153.

DOI：10.1007/s00445-010-0439-7

• Iliamna Volcano
• VT earthquake
• Earthquake swarms
• Stress tensor inversion
• Fault-plane solutions

A significant number of volcano-tectonic (VT) earthquake swarms, some of which are accompanied by ground deformation and/or volcanic gas emissions, do not culminate in an eruption. These swarms are often thought to represent stalled intrusions of magma into the mid- or shallow-level crust. Real-time assessment of the likelihood that a VT swarm will culminate in an eruption is one of the key challenges of volcano monitoring, and retrospective analysis of non-eruptive swarms provides an important framework for future assessments. Here we explore models for a non-eruptive VT earthquake swarm located beneath Iliamna Volcano, Alaska, in May 1996-June 1997 through calculation and inversion of fault-plane solutions for swarm and background periods, and through Coulomb stress modeling of faulting types and hypocenter locations observed during the swarm. Through a comparison of models of deep and shallow intrusions to swarm observations, we aim to test the hypothesis that the 1996-97 swarm represented a shallow intrusion, or "failed" eruption. Observations of the 1996-97 swarm are found to be consistent with several scenarios including both shallow and deep intrusion, most likely involving a relatively small volume of intruded magma and/or a low degree of magma pressurization corresponding to a relatively low likelihood of eruption.

• 出版日期2011-3