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Thermal regime, slab dehydration, and seismicity distribution beneath Hikurangi based on 3-D simulations

Citation

JI, Yingfeng; Yoshioka, Shoichi; Suenaga, Nobuaki (2017), Thermal regime, slab dehydration, and seismicity distribution beneath Hikurangi based on 3-D simulations, Dataset, https://doi.org/10.15146/R30029

Abstract

The downdip limit of brittle failure on seismogenic interfaces has been inferred primarily based on the thermal regime of subduction thrusts, but the three-dimensional (3-D) details remain poorly understood. To better understand the temperature and dewatering structure of the slab beneath the Hikurangi subduction zone, we construct a thermomechanical model that incorporates the up-to-date 3-D slab geometry and along-slab variations of the subduction velocities. The calculated thermal regime of the Hikurangi Plate leads to an identification of a zone of remarkable slab dehydration beneath the North Island that is distributed along the Kapiti-Manawatu-Raukumara (KMR). The average subduction-associated slab dehydration of 0.09 to 0.12 wt%/km is greater than the values in other portions of the subducted slab and possibly contributes to along-arc variations of the interplate pore fluid pressure. The large-scale slab dehydration (>0.05 wt%/km) and high thermal gradient (>4°C/km) identified in the KMR zone, which are caused by a higher in-situ dip angle, are associated with frequent deep slow slip events (SSEs). Intra-slab dehydration that exceeds 0.2 wt%/km beneath Manawatu, where tectonic tremors and associated regular earthquakes occur, suggests an unknown interactive relationship between the mechanisms.

Funding

Japan Society for the Promotion of Science, Award: 16H04040

Japan Society for the Promotion of Science, Award: 16H06477