Seismicity and tectonic tremor associated with shallow offshore slow slip along the northern Hikurangi Margin, New Zealand
Erin ToddPublished August 13, 2017, SCEC Contribution #7551, 2017 SCEC Annual Meeting Poster #065
Shallow (<15 km) slow slip events have been well documented offshore Gisborne on the northern Hikurangi Margin, New Zealand for over a decade. Gisborne slow slip events are associated with tectonic tremor downdip of the slow slip patch and increases in local microseismicity. The shallow subduction interface is often poorly resolved due to its distance from land where near source experiments can be conducted. To address this shortcoming, the Hikurangi Ocean Bottom Investigation of Tremor and Slow Slip deployed 24 absolute pressure gauges and 15 ocean bottom seismometers to the seafloor above the Gisborne slow slip patch to conduct a high-resolution investigation into the spatial and temporal extent of slow slip and associated tremor and earthquake activity. Here we present a detailed spatiotemporal analysis of the various interplate slip processes associated with the September/October 2014 Gisborne slow slip event in the shallow subduction environment. Tremor is collocated with slow slip and is localized over two subducted seamounts inside and updip of the geodetically determined slow slip patch. Coulomb failure stress change models suggest that seamount subduction plays a predominant role in the stress state of the shallow megathrust and that the observed interfingering of various interplate slip processes implies that stress changes from slow slip play a secondary role in the distribution of associated microseismicity.
Citation
Todd, E. (2017, 08). Seismicity and tectonic tremor associated with shallow offshore slow slip along the northern Hikurangi Margin, New Zealand. Poster Presentation at 2017 SCEC Annual Meeting.
Related Projects & Working Groups
Seismology
