Narrowband signals recorded near a moulin that are not moulin tremor: a cautionary short note
Geophysicists that deploy seismic sensors in ablation zones of glaciers and ice sheets to record glaciogenic signatures can confront recording challenges caused by instrument melt-out or tilt. These challenges often require installing sensors in boreholes to delay melt-out, or securing sensors to structures that improve coupling. We show that some of these structures that were buried near a moulin at a snow-free site in the ablation zone of the Western Greenland Ice Sheet resonated as they became exposed, and caused their geophones to record temporally evolving, narrowband signals that mimic features of glaciogenic sources like moulin tremor. We quantify these artifacts with a mechanical model that shows instruments undergo structural resonance as they melt-out, at exposure rates that we predict from an ablation model (RACMO). These models reproduce general spectral features in our data, and enable us to estimate what instrument exposure reduces ice-to-sensor coupling enough to prevent icequake detection. Last, we use our resonance data to quantitatively measure how narrowband signals that originate from either artificial or glaciogenic sources will reduce the ability of certain waveform detectors (correlators) to capture transient seismic events, even if sensors remain coupled.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- 89233218CNA000001
- OSTI ID:
- 1526961
- Report Number(s):
- LA-UR-18-31409
- Journal Information:
- Annals of Glaciology, Vol. 60, Issue 79; ISSN 0260-3055
- Publisher:
- International Glaciological SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Similar Records
Tidally Modulated Glacial Slip and Tremor at Helheim Glacier, Greenland
Tectonic tremor on Vancouver Island, Cascadia, modulated by the body and surface waves of the Mw 8.6 and 8.2, 2012 East Indian Ocean earthquakes: Tectonic Tremor on Vancouver Island