Seismogenesis at Hikurangi Integrated Research Experiment (SHIRE) onshore seismic acquisition field report

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Jacobs K, Henrys SA, Okaya D, Van Avendonk H, Black J, Barker DHN, Karalliyadda SC, Kurashimo E, Stratford WR, Savage M, Sullivan R, Bruce ZR, Hughes L, SHIRE Team. 2020. Seismogenesis at Hikurangi Integrated Research Experiment (SHIRE) onshore seismic acquisition field report. Lower Hutt (NZ): GNS Science. 136 p. (GNS Science report; 2019/19). doi:10.21420/PEQZ-BR17.

This report documents the acquisition and archiving of a major controlled source and passive seismic imaging project, the Seismogenesis Hikurangi Integrated Research Experiment (SHIRE). The SHIRE project aims to identify and quantify factors controlling the long-term evolution of the Hikurangi margin and the mode of slip along the subduction megathrust. The components of the data volume were acquired in two phases; between October 2017 – April 2018 (SHIRE I) and February–March 2019 (SHIRE II). The project was conducted by GNS Science; the University of Southern California, USA; the University of Texas Institute for Geophysics, USA; Victoria University of Wellington; and the Earthquake Research Institute, University of Tokyo, Japan. During SHIRE I, 5489 km of 2D seismic reflection data was collected offshore Bay of Plenty and East Coast by the R/V Marcus G. Langseth, and wide-angle refraction and reflection data were recorded onshore by 89 short-period seismograph sites along a transect from the Bay of Plenty to Gisborne and distributed array throughout the Tairāwhiti / Raukumara Peninsula. In addition, 25 short-period seismometers were located along the Bay of Plenty coast between October–December 2017. The SHIRE I land instruments also recorded signals from the 15 x 60 km volume of 3D seismic reflection data that was collected offshore Gisborne by the R/V Marcus G. Langseth during January 2018, plus four months of local and teleseismic earthquakes. SHIRE II aimed to directly image the crust beneath the Tairāwhiti / Raukumara Peninsula. Five borehole explosive sources were distributed along the central transect. The energy was recorded on 583 temporary seismograph stations comprising 304 vertical component and 269 three-component seismometers. The explosions were detonated during 26–28 February 2019. In addition, 19 SHIRE I 2D array sites were reoccupied for 20 days. The quality of the data recorded was excellent for all the explosion sources. (auth)