Preprints
https://doi.org/10.5194/se-2020-152
https://doi.org/10.5194/se-2020-152

  04 Oct 2020

04 Oct 2020

Review status: a revised version of this preprint was accepted for the journal SE and is expected to appear here in due course.

Seismic monitoring of the Auckland Volcanic Field during New Zealand's COVID-19 lock-down

Kasper van Wijk1, Calum J. Chamberlain2, Thomas Lecocq3, and Koen Van Noten3 Kasper van Wijk et al.
  • 1Department of Physics, University of Auckland
  • 2School of Geography Environment and Earth Sciences, Victoria University of Wellington
  • 3Royal Observatory of Belgiun

Abstract. The city of Auckland, New Zealand (Tamaki Makaurau, Aotearoa) sits on top of an active volcanic field. Seismic stations in and around the city monitor activity of the Auckland Volcanic Field (AVF), and provide data to image its subsurface. The seismic sensors – some positioned at the surface and others in boreholes – are generally noisier during the day than the night. For most stations weekdays are noisier than weekends, proving human activity contributes to recordings of seismic noise, even on seismographs as deep as 384 m below the surface, and as far as 15 km from Auckland's Central Business District. Lock-down measures in New Zealand to battle the spread of COVID-19 allow us to separate sources of seismic energy and evaluate both the quality of the monitoring network, as well as the level of local seismicity. A matched-filtering scheme based on template matching with known earthquakes improved the existing catalogue of 5 known local earthquakes to 35 for the period between November 1st, 2019 and June 15th, 2020. However, the Level 4 lock-down from March 25th to April 27th – with its drop in anthropogenic seismic noise – did not mark an enhanced detection level. Nevertheless, it may be that wind and ocean swell mask the presence of weak local seismicity, particularly near surface-mounted seismographs in the Hauraki Gulf that show much higher levels of noise than the rest of the local network.

Kasper van Wijk et al.

 
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Kasper van Wijk et al.

Kasper van Wijk et al.

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Short summary
The Auckland Volcanic Field is monitored by a seismic network. The lockdown measures to combat COVID-19 in New Zealand proved an opportunity to evaluate the performance of the seismic stations in the network, and to search for small(er) local earthquakes, potentially hidden in the noise during normal times.