Wallace, L.M.; Jacobs, K.M.; Palmer, N.G.; Perez, A.; Pita-Sllim, O.; Warren-Smith, E.; TAN2013 Science Party. 2026 Voyage report TAN2013 and TAN2102: physical processes underlying slow earthquakes (PULSE I). Lower Hutt, NZ: Earth Sciences New Zealand. GNS Science report 2025/11. 63 p.; doi: 10.21420/FNME-D672
Abstract
The PULSE deployment is a multi-institutional, international, seafloor geodetic and seismological investigation of shallow slow-slip events on the Hikurangi subduction thrust offshore of New Zealand’s North Island’s east coast. Continuously operating Global Navigation Satellite System (GNSS) sites in the North Island reveal the shallowest, well-documented slow-slip events anywhere on Earth. As part of the previous Hikurangi Ocean Bottom Investigation of Tremor and Slow Slip (HOBITSS) experiment, we have deployed (TAN1405), then recovered and re-deployed (RR1507, TAN1607, TAN1705, TAN1809, TAN1907) ocean-bottom instruments belonging to GNS Science (now part of Earth Sciences New Zealand), as well as United States of America and Japanese institutions, to document deformation and seismicity during large slow-slip events offshore of the North Island’s east coast. The current PULSE experiment is intended to capture vertical crustal deformation and seismicity related to an anticipated slow-slip event offshore from the Pōrangahau region of southern Hawke’s Bay / northern Wairarapa. Previous Pōrangahau slow-slip events have occurred on a five-yearly basis in 2006, 2011 and 2016, so the next occurrence was expected to occur sometime in 2021. The offshore deployment was complemented by an extensive onshore deployment of seismometers and temporary GNSS instruments, starting in June 2021. As part of the PULSE experiment, TAN2013 deployed14 bottom-pressure recorders (BPRs; belonging to GNS Science, the University of Texas and Tohoku University), and 10 ocean bottom seismometers (belonging to the University of Tokyo). We also recovered five BPRs that were deployed on TAN1907 offshore of Gisborne along a transect ofsub-seafloor observatories, installed to monitor slow slip offshore of Gisborne. Work undertaken on TAN2013 was supported under the Ministry of Business, Innovation & Employment (MBIE) Endeavour-funded project ‘Diagnosing peril posed by the Hikurangi subduction zone’ (Contract C05X1605) and a Marsden Fund Grant awarded to GNS Science (‘Tipping the balance: what makes slow earthquakes episodic’) (auths)
