[S-CG52] Inter-segment Tectonics: Interdisciplinary Research on Responses to Plate Subduction

[SCG52-09] Crustal Structure of the Hikurangi Subduction Zone Revealed by Four Decades of Onshore-Offshore Seismic Data

*Dan Bassett¹、Stuart Henrys¹、Brook Tozer¹、Harm van Avendonk²、Andrew Gase²、Nathan Bangs²、Shuichi Kodaira³、David A Okaya⁴、Katie Jacobs¹、Rupert Sutherland⁵、Hannu Seebeck¹、Gou Fujie³、Kimihiro Mochizuki⁶、Martha K Savage⁵ (1.GNS Science、2.University of Texas at Austin、3.JAMSTEC、4.University of Southern California、5.Victoria University of Wellington、6.Earthquake Research Institute - University of Tokyo)

Crustal scale architecture and the properties of the overthrusting and subducting plates have been shown to play key roles in modulating the rupture area, slip-distribution and magnitude of earthquakes, and their proximity to densely populated coastal regions or deep-sea trenches. However, constraining the crustal scale architecture of subduction zones at high-resolution over scales comparable to the rupture area of the largest earthquakes (∼50,000–250,000 km²) is a significant challenge.

In this presentation, I will describe how four decades of onshore-offshore, ocean bottom seismometer and marine multi-channel seismic data have been integrated to constrain the crustal structure of the entire Hikurangi subduction zone. Our method provides refined 3-D constraints on the width and properties of the frontal prism, the thickness and geological architecture of the forearc crust, and the crustal structure and geometry of the subducting Hikurangi Plateau to 40 km depth. Our results reveal significant along-strike changes in the distribution of rigid crustal rocks in the overthrusting plate and along-strike changes in the crustal thickness of the subducting Hikurangi Plateau.

In this presentation, we will integrate our tomographic model with onshore geology, tectonic reconstructions and geodetic observations to describe the relationship between crustal structure and fault-slip behavior along the Hikurangi margin.