loading page

Low-frequency earthquakes accompany deep slow slip beneath the North Island of New Zealand
  • +3
  • Florent Aden-Antoniow,
  • William Benjamin Frank,
  • Calum John Chamberlain,
  • John Townend,
  • Laura Wallace,
  • Stephen Bannister
Florent Aden-Antoniow
GNS

Corresponding Author:[email protected]

Author Profile
William Benjamin Frank
Massachusetts Institute of Technology
Author Profile
Calum John Chamberlain
Victoria University of Wellington
Author Profile
John Townend
Victoria University of Wellington
Author Profile
Laura Wallace
GNS Science
Author Profile
Stephen Bannister
GNS Science
Author Profile

Abstract

Slow slip events have previously been observed along the Hikurangi subduction zone beneath the North Island of New Zealand. These slow slip episodes occur both on the shallow plate interface (< 15km depth) and at the deeper end of the seismogenic zone (> 30km depth). We present the first catalog of low-frequency earthquakes (LFEs) in the Hikurangi subduction zone, located beneath the Kaimanawa Range on the central Hikurangi margin, downdip of a region that regularly (every 4-5 years) hosts M7 slow slip events. To systematically detect LFEs using continuous seismic data recorded by GeoNet, we developed a matched-filter technique with template waveforms derived from previous observations of tectonic tremor. The workflow presented in this work is composed of two iterations of a matched-filter search. In each iteration, the detections were gathered into families and their common waveforms postprocessed with machine-learning methods to extract high-quality waveforms, allowing us to pick seismic phase arrivals with which to locate the LFEs. We found that LFEs occur in episodes of intense activity during the neighboring updip M7 slow slip events. We also observe a recurrence time of 2 years between other large bursts of LFEs, suggestive of a shorter cycle of slow slip. We hypothesize that these and other frequent LFE episodes highlight smaller slow transients that have not yet been geodetically observed.