Observational Evidence of a Very-low-frequency Earthquake (Mw 3.8) Leading to an Earthquake (Mw 4.2): Minto Flats Strike-slip Fault Zone, Central Alaska
Description:
The physical conditions governing earthquake initiation are largely unknown, particularly at time scales immediately preceding rupture. While there is geodetic and seismic evidence of precursory activity in the hours to weeks prior to large earthquakes, the observational evidence immediately preceding the earthquake rupture is limited and controversial. Here we present evidence of a well-recorded event from the Minto Flats fault zone in central Alaska. The event initiated as a high-frequency signal lasting 19 s accompanied by a Mw 3.8 very-low-frequency earthquake (VLFE) on a dipping strike-slip fault. After 24 s of combined high-frequency signal and VLFE, a Mw 4.2 earthquake occurred having the same source mechanism as the VLFE. The precursory activity provides evidence for exceptional conditions for earthquake initiation. These observations highlight the Minto Flats fault zone as a natural laboratory for investigating earthquake initiation processes and provide constraints for numerical and laboratory models of earthquake nucleation.
Session: SSJ-SSOC-SSA Joint Session: From Slow to Fast Earthquakes: Bridging the Spectrum of Fault Slip [Poster]
Type: Poster
Date: 4/16/2026
Presentation Time: 08:00 AM (local time)
Presenting Author: Amanda McPherson
Student Presenter: Yes
Invited Presentation:
Poster Number: 148
Authors
Amanda McPherson Presenting Author Corresponding Author ammcpherson@alaska.edu University of Alaska Fairbanks |
Carl Tape ctape@alaska.edu University of Alaska Fairbanks |
Yoshihiro Kaneko kaneko.yoshihiro.4e@kyoto-u.ac.jp Kyoto University |
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Observational Evidence of a Very-low-frequency Earthquake (Mw 3.8) Leading to an Earthquake (Mw 4.2): Minto Flats Strike-slip Fault Zone, Central Alaska
Category
SSJ-SSOC-SSA Joint Session: From Slow to Fast Earthquakes: Bridging the Spectrum of Fault Slip