Interactions between tectonic plates at subduction zones are responsible for generating the world's largest known earthquakes (magnitudes 8+) as well as slow-slip events (SSEs). SSEs may take place over days to years, and are not felt by people. What controls the occurrence of SSEs and how they are related to large subduction zone earthquakes is not known. At the subduction zone along the east coast of New Zealand SSEs occur every 1-2 years and many studies have focused on this region to get a better understanding of SSEs. A 3-dimensional seismic data set has been collected in a region of SSEs along the New Zealand margin and this project will process these data to understand the fault systems and fluid flow systems in the region and the impact of these systems on SSEs. The results will aid in the assessment of earthquake and tsunami hazards at subduction zones. The project supports the training of two early career scientists and a graduate student.
Slow-slip events (SSEs) involve transient aseismic slips on a fault that last days to years. SSEs have been observed in a number of subduction zones worldwide, yet the physical mechanisms that control this type of slip remain poorly understood. At the Hikurangi margin offshore the east coast of New Zealand, well documented SSEs recur every 1-2 years at the shallow portion (~2-15 km depth) of the subduction megathrust. This provides an ideal opportunity to examine the structural and hydrogeological conditions that contribute to the generation of SSEs through detailed seismic imaging and seismic attribute measurements. A team of scientists acquired a 3-D seismic volume within a 14.7 x 60 km survey area on the northern Hikurangi margin. This 3-D dataset, with complete coverage and excellent quality, shows great potential to reveal the conditions along the plate interface and the development of these conditions. The 3-D volume will be processed with state-of-the-art 3-D pre-stack time and depth migration to image the highest possible level of structural detail while preserving reflection characteristics. The data will be analyzed and interpreted to investigate fluid flow and tectonic development of the margin.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
