Estimation of stress state and detailed structure at shallow plate boundary based on 3D seismic data

Abstract

The Earth's crust is a dynamic place, consisting of the large tectonic plates that sit atop the mantle, the extremely hot, high pressure zone of material between the crust and the core. The first several tens kilometres of the Earth's shell, the crust and uppermost mantle, is moving and shifting, causing the oceanic and continental plates to bang and crash with one another, resulting in the earthquakes and tsunamis that dramatically impact the countries at the boundaries of the plates. While the world takes notice when one of these disasters happen, we don't realise that there is constant activity in these zones causing measurable seismic waves to regularly ripple through the crust. Using artificially-generated seismic waves can help researchers to understand more about how the crust and upper mantle behave. Depending on the positioning of the plates and the nature of the crust, i.e., thickness, direction of movement and composition, the behaviour will differ. By using 'controlled sources' in marine seismic experiments, such as air-gun shooting, scientists are able to gather as much data as possible regarding the factors influencing the behaviours of the plates to help provide a better understanding of the processes leading to earthquakes.One organisation that builds and operates via international collaboration is the Japan Agency For Marine-Earth Science and Technology (JAMSTEC). Dr Ryuta Arai joined the Structural Seismology Group of JAMSTEC in 2014 and is now a scientist at the Research Institute for Marine Geodynamics of JAMSTEC. Arai is part of a team of researchers from Japan, New Zealand, the United States and the United Kingdom who are investigating the physical properties of the seismogenic area in the Hikurangi subduction zone.