PhD Project Description

Thesis Title: Discriminating between spatial and temporal variations in seismic anisotropy at active volcanoes

Using a dense observational network and an automated shear wave splitting analysis, we examine local earthquakes occurring in 2008 within 100 km of Mt. Ruapehu.
We introduce a spatial averaging technique and a two-dimensional tomography of recorded delay times, to observe the spatial variation in more detail. We use this new method to create a benchmark of spatial variations in shear wave anisotropy around Mt. Ruapehu, against which future temporal changes may be measured.
Data from past deployments of three-component seismometers have been analysed and we identify a transient region of strong anisotropy centred on the volcano during the major magmatic eruption of 1995.
We also introduce a method of analysing temporal variations in seismic anisotropy at active volcanoes by using tight clusters of earthquakes and highly correlated multiplets.
Finally, we apply some of these methods to data from the 2008 eruption of Okmok volcano, Alaska.