The 2019 Whakaari (White Island) Volcano-tectonic Event as Seen From Time-space Earthquake Patterns
Abstract
The tectonic setting of New Zealand's Bay of Plenty is defined by both magmatic rifting in the Taupo volcanic zone (TVZ) onshore, as well as back-arc spreading in the Havre trough offshore above the Hikurangi subduction zone. The transition between the two domains is the Whakatane graben, which hosts the active composite Whakaari (commonly known as White Island) volcano. Whakaari has recently been New Zealand's most active volcano, and it was the site of intense earthquake swarms in May and June 2019. A second swarm occurred closer to the coastline during this period. Unfortunately, our array was removed 2 months before the tragic phreato-magmatic eruption at Whakaari in December. Our objectives are to determine the time sequence of the earthquakes, and to place this activity within the larger tectonic context of the Whakatane graben in the transition between continental rifting and back-arc spreading. P and S-wave first arrivals were picked manually on vertical and transverse components, respectively, from the Back-Arc Rifting New Zealand (BARNZ) array and GEONET permanent stations for the May-July, 2019 earthquakes in the Whakatane graben and Whakaari volcano swarms. Earthquake locations from absolute and double difference methods are displayed in a 3D visualization to show the time sequence of earthquakes, and to compare them to surface observations reported by the Global Volcanism Program and Geonet. Focal mechanism solutions from the earthquake swarms provide information on the kinematics of faulting, and possible magma-fault interactions.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMED0370032A
- Keywords:
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- 0810 Post-secondary education;
- EDUCATION;
- 0855 Diversity;
- EDUCATION