The influence of environmental microseismicity on detection and interpretation of small-magnitude events in a polar glacier setting
- Univ. of Alaska, Fairbanks, AK (United States)
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Oregon State Univ., Corvallis, OR (United States)
Glacial environments exhibit temporally variable microseismicity. To investigate how microseismicity influences event detection, we implement two noise-adaptive digital power detectors to process seismic data from Taylor Glacier, Antarctica. We add scaled icequake waveforms to the original data stream, run detectors on the hybrid data stream to estimate reliable detection magnitudes and compare analytical magnitudes predicted from an ice crack source model. We find that detection capability is influenced by environmental microseismicity for seismic events with source size comparable to thermal penetration depths. When event counts and minimum detectable event sizes change in the same direction (i.e. increase in event counts and minimum detectable event size), we interpret measured seismicity changes as ‘true’ seismicity changes rather than as changes in detection. Generally, one detector (two degree of freedom (2dof)) outperforms the other: it identifies more events, a more prominent summertime diurnal signal and maintains a higher detection capability. We conclude that real physical processes are responsible for the summertime diurnal inter-detector difference. One detector (3dof) identifies this process as environmental microseismicity; the other detector (2dof) identifies it as elevated waveform activity. Our analysis provides an example for minimizing detection biases and estimating source sizes when interpreting temporal seismicity patterns to better infer glacial seismogenic processes.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- 89233218CNA000001
- OSTI ID:
- 1699461
- Report Number(s):
- LA-UR--19-31851
- Journal Information:
- Journal of Glaciology, Journal Name: Journal of Glaciology Journal Issue: 259 Vol. 66; ISSN 0022-1430
- Publisher:
- International Glaciological SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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