Seismotectonics in New Zealand
New Zealand sits on the boundary between the Australian and Pacific tectonic plates, making it an exciting natural laboratory for studying a variety of active tectonic processes!
Seamount subduction along the northern Hikurangi Margin
One of my ongoing projects is to use seismic and cGPS data to understand the relationship between slow slip, tremor where seamounts on the rough incoming Pacific Plate subduct beneath the Australian plate along the northern Hikurangi Margin. This work contributes to a multidisciplinary investigation of seismic and aseismic response to fluid pressure changes in fracture networks associated with seamount subduction. This work also fits in with IODP scientific drilling projects to measure the physical properties of rocks that can host slow slip. See Todd et al., 2018 and Barker et al., 2018.
Tectonic tremor associated with shallow slow slip
As part of another project, I have been analysing the spatiotemporal relationship between seismicity and tectonic tremor with respect to a slow slip events along the northern Hikurangi Margin, New Zealand. Using land-based data from the New Zealand National Seismograph Network (operated by GeoNet; https://www.geonet.org.nz/) and offshore data from ocean bottom seismometers and absolute pressure gauges, I have been characterising the occurrence of tectonic tremor and microseismicity associated with slow slip since 2011. As part of the Hikurangi Ocean Bottom Investigation of Tremor and Slow Slip (HOBITSS) experiment, offshore instruments were originally deployed in May 2014 and have greatly improved our understanding of shallow slow slip and its associated seismicity. See Todd and Schwartz 2016 and Todd et al., 2018.
characterising seismicity in low seismicity regions like Dunedin
As part of a large Natural Hazards Research Platform project called Unknown Faults Under Cities, I have been analyzing seismic data from three seismic arrays deployed in Dunedin City in 2016 to investigate the occurrence of tectonic tremor indicating predominantly aseismic active deformation on faults at depth, microseismicity, and repeating earthquakes. Improving earthquake catalogues in regions of low seismicity can contribute a better understanding of earthquake hazards. See Villamor et al., 2018. Ongoing.
The 2011 northern Kermadec earthquake doublet and subduction zone faulting interactions
After a large earthquake doublet in the outer trench slope of the central Kermadec Arc, I analysed the event source parameters using a finite fault model to determine the focal mechanism and slip distribution on the fault. As part of this study, I also calculated Coulomb stress interactions between the intraplate and interplate faulting observed in this doublet sequence. See Todd & Lay, 2013.