Repeating Earthquakes around the Raukumara Peninsula, North Island, New Zealand
Abstract
Repeating earthquakes can provide useful insights into fault-zone processes operating at seismogenic depths. Characterizing these processes is important for seismic hazard analysis and for understanding interactions between different types of seismicity. We have conducted an exhaustive search of the New Zealand national earthquake catalog to identify well-correlated events. We first clustered the catalog by distance, before undertaking initial correlation analysis of each cluster to search for potentially repeating events. From this initial nationwide catalog of possible repeaters, we focused on clusters surrounding the Raukumara Peninsula, North Island. The Raukumara Peninsula has experienced a range of transient deformation phenomena during the last decade, including repeated slow-slip and moderate shaking caused by nearby large earthquakes. In our work to date we have focused on refining the criteria used to identify and classify repeating earthquakes in New Zealand, and these criteria will be used in future searches in other regions. We have targeted earthquakes recorded by GeoNet between 2004 and 2018, which provides the longest-duration data-set from continually running seismic stations and allows for the comparison of waveforms at multiple locations. In order for events to be identified as repeating, we require their waveforms to have a cross-correlation and/or coherence of at least 0.96, at two or more stations. Additionally, precise relative locations of all the events were computed to confirm overlapping source locations. Once repeaters were identified, we constructed a catalog of event locations and magnitudes for each repeating family around the Raukumara Peninsula. This has revealed that the events are predominantly occurring in the upper plate, at depths shallower than 15km, rather than along the subduction interface. Repeating earthquakes can now be added to the diverse range of seismic phenomenon already observed in this region.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.T43G0387H
- Keywords:
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- 1242 Seismic cycle related deformations;
- GEODESY AND GRAVITY;
- 7223 Earthquake interaction;
- forecasting;
- and prediction;
- SEISMOLOGY;
- 8118 Dynamics and mechanics of faulting;
- TECTONOPHYSICS;
- 8163 Rheology and friction of fault zones;
- TECTONOPHYSICS