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Session: Observations of Volcanism in the Three Spheres: Land, Air and Sea [Poster]

Type: Poster

Date: 4/26/2019

Time: 06:00 PM

Room: Fifth Avenue

[Withdrawn] Repeating Deep Long-Period Earthquakes Beneath Mauna Kea Volcano

Mauna Kea is a large postshield-stage volcano that forms the highest peak on Hawaii Island. The 4,205-meter high volcano erupted most recently between 6,000 and 4,500 years ago and exhibits relatively low rates of seismicity, which are mostly tectonic in origin resulting from lithospheric flexure under the weight of the edifice. Here we identify repeating, deep long-period earthquakes (DLPs) occurring beneath the summit of Mauna Kea. These earthquakes, which are not part of the Hawaiian Volcano Observatory’s regional network catalog, were initially detected through a systematic search for coherent seismicity using envelope cross-correlation, and subsequent analysis revealed the presence of a long-term, persistent source. The events have energy concentrated at 2-7 Hz, and can be seen in filtered waveforms dating back to the earliest continuous data from a single station archived at IRIS from November 1999. We use a single-station (horizontal components) match-filter analysis to create a catalog of the repeating earthquakes for the past 18 years. Using templates created through the stacking of thousands of sta/lta-triggers, we find > 1 million earthquakes repeating every 7-12 minutes throughout this time period, in addition to many smaller events occurring in between. The earthquakes occur at 28-31 km within a conspicuous gap in seismicity depth directly beneath the summit that corresponds to a low-velocity anomaly in regional tomography model. Magnitudes (~Ml 1.3-1.6) and periodicity are remarkably stable over time periods of years but do vary slightly on shorter time scales, and the DLPs can be triggered or modified by regional tectonic earthquakes. Based on the events’ frequency content and location, we infer a volcanic source distinct from the regional tectonic seismicity responding to the load of the island.

Presenting Author: Aaron Wech

Additional Authors