Physically Understanding Localized Slip Episodisity

Subudction zones, where one tectonic palte descends benath another, produce the planet's largest earthquakes and tsunami; but what controls the timing of fault slip in these events? The recent discovery of frequent, semi-predictable slow-motion earthquakes (lasting days to years) on subudction faults, provide an untapped opportunity to investigate what tips the balance on these faults, causing them to fail. Slow-motion earthquakes on the Hikurangi subduction zone offshore New Zealand's east coast are remarkable for the range of slow and fast (seismic) slip processes occurring at shallow depths (<10 km), offering a globally unique opportunity to resolve processes driving slip on subduction zones, using near-field monitoring. Our project is designed to detect localized fault zone changes prior to slow earthquakes, revelaing the physical mechanims that regulate slip timing on a major fault capable of generating devastating earthquakes and tsunami. We use onshore and offshore sensors coupled with novel geophysical methods to detect high-resolution changes in fault properties leading into an upcoming slow-slip event offshore southern Hawkes Bay, and a recent Gisborne event. Resolving these changes will determine whether seismologically-observed changes in fault properties preceded slip, ultimately enabling future development of more accurate forecasts of both slow and possibly fast (seismic slip earthquakes.