Earthquakes and Locking inVEstigation of Subduction (ELVES)

Seismological investigation of the locked section of the Hikurangi subduction thrust offshore New Zealand's North Island's east coast, using broadband ocean-bottom seismographs. This project is a collaboration between scientists from GNS Science, Te Herenga Waka/Victoria University of Wellington, the University of Ottawa and Dalhousie University. Data has been collected over a roughly one-year deployment of a loose grid of BOBS, of which 18 instruments were successfully recovered.

The subduction interface below and offshore the Wellington region is currently "locked", building up stress that will be released in a large, probably destructive subduction thrust earthquake. However, the existing land-based GeoNet network is effectively blind to small earthquakes offshore, and even large earthquakes are not well located, hindering understanding of the hazard posed by the offshore subduction zone. Records from the OBS deployed here will enable (1) recordings of small earthquakes to (2) identify active fault structures and (3) help to determine how much stress is accumulating offshore. Furthermore, this data will provide constraints on rates of offshore seismicity, fault geometries, and on the up-dip limit of the seismogenic zone. These data are needed to improve a range of efforts that seek to better constrain the hazard and risk posed to Aotearoa.