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Using Deep Long-Period Earthquakes to Constrain Magmatic Volatile Transport at Mauna Kea

Description: 

Seismic signals generated at volcanoes, such as deep long-period earthquakes (DLPs), can result from diverse physical processes, posing challenges for the interpretation of such signals. However, Mauna Kea provides a unique setting to explore the processes behind DLPs due to a large and well-characterized catalog of these events. Between 2000 and 2019, beneath Mauna Kea, over 1 million DLPs occurred near periodically with interevent times between 7 to 12 minutes. Wech et al. (2020) cataloged and characterized these events, locating them at ~22 km b.s.l. beneath Mauna Kea and constraining their primarily non-double-couple source mechanisms. The authors proposed a conceptual model for these repeating events where stalled, crystallizing mush at the base of the crust results in second-boiling driven degassing. The degassing supplies magmatic volatiles to an overlying network of pre-existing fractures generating the DLPs. From this conceptual model, we have developed a physics-based numerical crack model for these repeating DLPs from which we compute synthetic seismograms. By tuning the model parameters and comparing the resulting synthetic seismograms to observed seismograms, we successfully reproduce observations such as the p-wave first motions and the amplitudes of these events. Furthermore, the range of suitable parameters from the tuned crack model provides valuable insight into the elastic properties of the rock surrounding the fractures, fracture system size and geometry, and magmatic volatile supply rates to the fractures—quantities otherwise poorly constrained at lower crustal depths in magmatic plumbing systems. More broadly, this approach improves our understanding of one potential source of seismicity at volcanoes and provides novel insight into passive degassing of magmatic volatiles.

Session: Seismoacoustic, Geodetic and Other Geophysical Investigations of Active Volcanoes - I

Type: Oral

Date: 5/3/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Kathryn

Student Presenter: Yes

Invited Presentation: 

Authors