P and S wave travel time tomography of the SE Asia-Australia collision zone
© 2019 Elsevier B.V. The southeast (SE)Asia - Australia collision zone is one of the most tectonically active and seismogenic regions in the world. Here, we present new 3-D P- and S-wave velocity models of the crust and upper mantle by applying regional earthquake travel-time tomography to global catalogue data. We first re-locate earthquakes provided by the standard ISC-Reviewed and ISC-EHB catalogues using a non-linear oct-tree scheme. A machine learning algorithm that clusters earthquakes depending on their spatiotemporal density was then applied to significantly improve the consistency of travel-time picks. We used the Fast Marching Tomography software package to retrieve 3-D velocity a…
The Coupled Magmatic and Hydrothermal Systems of the Restless Aluto Caldera, Ethiopia
Seismicity can be used to better understand interactions between magma bodies, hydrothermal systems and their host rocks—key factors influencing volcanic unrest. Here, we use earthquake data to image, for the first time, the seismic velocity structure beneath Aluto, a deforming volcano in the Main Ethiopian Rift. Traveltime tomography is used to jointly relocate seismicity and image 3D P- and S-wave velocity structures and the ratio between them (V P/V S). At depths of 4–9 km, the seismicity maps the top of a large low velocity zone with high V P/V S, which we interpret as a more ductile and melt-bearing region. A shallow (<3 km) hydrothermal system exhibits low seismic velocities and ve…