tectonic tremor
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2021 ◽  
Vol 576 ◽  
pp. 117238
Author(s):  
Kyungjae Im ◽  
Jean-Philippe Avouac
Keyword(s):  

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Evgeny A. Podolskiy ◽  
Yoshio Murai ◽  
Naoya Kanna ◽  
Shin Sugiyama

AbstractShearing along subduction zones, laboratory experiments on analogue faults, and sliding along glacier beds are all associated with aseismic and co-seismic slip. In this study, an ocean-bottom seismometer is deployed near the terminus of a Greenlandic tidewater glacier, effectively insulating the signal from the extremely noisy surface seismic wavefield. Continuous, tide-modulated tremor related to ice speed is recorded at the bed of the glacier. When noise interference (for example, due to strong winds) is low, the tremor is also confirmed via analysis of seismic waveforms from surface stations. The signal resembles the tectonic tremor commonly observed during slow-earthquake events in subduction zones. We propose that the glacier sliding velocity can be retrieved from the observed seismic noise. Our approach may open new opportunities for monitoring calving-front processes in one of the most difficult-to-access cryospheric environments.


Author(s):  
Yasunori Sawaki ◽  
Yoshihiro Ito ◽  
Kazuaki Ohta ◽  
Takuo Shibutani ◽  
Tomotaka Iwata

Author(s):  
Keita Nakamoto ◽  
Yoshihiro Hiramatsu ◽  
Takanori Matsuzawa ◽  
Tomoyuki Mizukami

2021 ◽  
Author(s):  
Claudia Hulbert ◽  
Romain Jolivet ◽  
Blandine Gardonio ◽  
Paul Johnson ◽  
Christopher Ren ◽  
...  

<p>Active faults release tectonic stress imposed by plate motion through a spectrum of slip modes, from slow, aseismic slip, to dynamic, seismic events. Slow earthquakes are often associated with tectonic tremor, non-impulsive signals that can easily be buried in seismic noise and go undetected. </p><p>We present a new methodology aimed at improving the detection and location of tremors hidden within seismic noise. After detecting tremors with a classic convolutional neural network, we rely on neural network attribution to extract core tremor signatures. By identifying and extracting tremor characteristics, in particular in the frequency domain, the attribution analysis allows us to uncover structure in the data and denoise input waveforms. In particular, we show that these cleaned signals correspond to a waveform traveling in the Earth's crust and mantle at wavespeeds consistent with local estimates. We then use these cleaned waveforms to locate tremors with standard array-based techniques. </p><p>We apply this method to the Cascadia subduction zone. We analyze a slow slip event that occurred in 2018 below the southern end of the Vancouver Island, Canada, where we identify tremor patches consistent with existing catalogs. Having validated our new methodology in a well-studied area, we further apply it to various tectonic contexts and discuss the implications of tremor occurrences in the scope of exploring the interplay between seismic and aseismic slip.</p>


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