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The September 16, 2023 Greenland Event: Mysterious Days-Long Monochromatic Very Long-Period Signal Triggered by a Landslide

Description: 

Peculiar, energetic seismic signals were generated close to the Dickson Fjord, a remote area of East Greenland on September 16, 2023, followed by a large tsunami, which impacted the northern shore of Ella Island. Using high-resolution Planet Labs Dove mini-satellite imagery we identify that a landslide occurred on the Southern side of the Dickson Fjord on the same day. Seismic signals were recorded at regional to teleseismic distances. Besides a first strong transient signal in the range of 0.02-0.06 Hz, which we attribute to the landslide, a very long (~50 hours), low-frequency, monochromatic (~0.01 Hz) signal was observed at teleseismic distances. We modeled full waveform broadband seismic data to invert for the seismic sources for both types of signals using moment tensor and single force models. The first transient signal is well reproduced at regional distances by single and double source models, which are consistent with the landslide process. The long lasting oscillating signal is modeled at teleseismic distances by a damped dipole oscillator, which reproduces the pattern of Love and Rayleigh waves observed at different azimuths. By combining different data and source models with the Fjord system geometry, we are able to reconstruct the complex source process.

Session: Detecting, Characterizing and Monitoring Mass Movements [Poster Session]

Type: Poster

Date: 5/2/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Torsten

Student Presenter: No

Invited Presentation: 

Authors