@article{vanWijk:5033,
author = "van Wijk, Kasper and Chamberlain, Callum J and Lecocq,
Thomas and Van Noten, Koen",
title = "{Seismic monitoring of the Auckland Volcanic Field during
New Zealand's COVID-19 lock-down}",
year = "2021",
note = "The city of Auckland, New Zealand (Tāmaki 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 during nighttime. 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.
Lockdown 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 and the
level of local seismicity. A matched-filtering scheme based
on template matching with known earthquakes improved the
existing catalogue of five known local earthquakes to 35
for the period between 1 November 2019 and 15 June 2020.
However, the Level-4 lockdown from 25 March to 27 April –
with its drop in anthropogenic seismic noise above 1 Hz
– 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.",
}