Discrimination between icequakes and earthquakes in southern Alaska: an exploration of waveform features using Random Forest algorithm

• Published in: Geophysical Journal International
• Main Authors: Kharita, Akash, Denolle, Marine A, West, Michael E
• Format: Article in Journal/Newspaper
• Language: English
• Published: Oxford University Press (OUP) 2024
• Subjects: Geochemistry and Petrology; Geophysics; glacier; glaciers; Alaska
• Online Access: http://dx.doi.org/10.1093/gji/ggae106; https://academic.oup.com/gji/advance-article-pdf/doi/10.1093/gji/ggae106/56975929/ggae106.pdf; https://academic.oup.com/gji/article-pdf/237/2/1189/57133554/ggae106.pdf

SUMMARY This study examines the feature space of seismic waveforms often used in machine learning applications for seismic event detection and classification problems. Our investigation centres on the southern Alaska region, where the seismic record captures diverse seismic activity, notably from the calving of marine-terminating glaciers and tectonic earthquakes along active plate boundaries. While the automated discrimination of earthquakes and glacier quakes is our nominal goal, this data set provides an outstanding opportunity to explore the general feature space of regional seismic phases. That objective has applicability beyond ice quakes and our geographic region of study. We make a noteworthy discovery that features rooted in the spectral content of seismic waveforms consistently outperform statistical and temporal features. Spectral features demonstrate robust performance, exhibiting resilience to class imbalance while being minimally impacted by factors such as epicentral distance and signal-to-noise ratio. We also conduct experiments on the transferability of the model and find that transferability primarily depends on the appearance of the waveforms. Finally, we analyse misclassified events and find examples that are identified incorrectly in the original regional catalogue.