A Repeating Earthquake Catalog From 2003 to 2020 for the Raukumara Peninsula, Northern Hikurangi Subduction Margin, New Zealand

Abstract

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 61 repeating earthquake families occurring between 2003 and 2020, consisting of 347 individual earthquakes. These families have a magnitude range of ML 1.7–5.2 and recurrence intervals of < 1 to ∼7 yrs. Repeating earthquakes in 9 of the 11 regional groups identified in this study coincide spatiotemporally with previously identified slow‐slip events and tremor. However, the responses shown to slow‐slip are not consistent within families or within regional groups.

Keywords

• correlation
• Hikurangi
• repeating earthquakes
• slow‐slip