A Repeating Earthquake Catalog from 2003 to 2018 for the Raukumara
Peninsula, Northern Hikurangi Subduction Margin, New Zealand
Abstract
Repeating earthquakes provide a novel way of monitoring how stresses
load faults between large earthquakes. To date, however, and despite the
availability of long-duration, high-quality seismological datasets,
little attention has been paid to tectonic repeating earthquakes in New
Zealand. We develop a workflow and composite criterion for identifying
repeating earthquakes in New Zealand, using data from the GeoNet
permanent seismic network, and present New Zealand’s first decadal-scale
repeating earthquake catalog. For events to be identified as repeating
in this study, two or more events must have a normalized
cross-correlation of at least 0.95 at two or more seismic stations, when
calculated for 75% of the earthquake coda. By applying our composite
criterion to seismicity around the Raukumara Peninsula, northern
Hikurangi subduction margin, we have identified 62 repeating earthquake
families occurring between 2003 and 2018, consisting of 160 individual
earthquakes. These families have a magnitude range of MW 1.5-4.5 and
recurrence intervals of < 1-12 years. The repeating earthquake
families identified in this study coincide with the location and timing
of previously identified slow-slip events and tremor. However, the
responses shown to slow-slip are not consistent within families or
within regional groups.