ANZIC 's Inaugural Distinguished Lecturer – Professor Laura Wallace: Unlocking slow slip secrets with IODP .

Laura is a geophysicist at GEOMAR and Australian & New Zealand International Scientific Drilling Consortium's (ANZIC) first, and only, female Co-Chief Scientist in the 57-year history of the International Ocean Discovery Program (IODP).

A global pioneer in slow slip event (SSE) research, Laura led IODP Expedition 375, where her team installed one of just two borehole observatories in the Southern Hemisphere at New Zealand’s Hikurangi Subduction Zone. Her groundbreaking work is helping unlock the secrets of fault mechanics and is transforming seismic hazard prediction through long-term, cutting-edge monitoring.

Abstract

The discovery that slow slip events (SSE s lasting days to years) play a major role in the accommodation of plate motion at subduction zones has transformed our understanding of fault mechanics and earthquake processes. However, many outstanding questions remain regarding the physical processes and properties that promote slow slip event occurrence, and their distribution.

The northern Hikurangi subduction zone offshore New Zealand hosts the world’s shallowest, well-documented slow slip events, and presents a globally unique opportunity to use scientific ocean drilling to reveal the physical properties and processes that produce shallow SSE s. The close proximity of these events to the seafloor (less than a few km) offers important opportunities to monitor crustal deformation during SSE s in the very near-field with borehole observatories.

During IODP Expeditions 372 and 375, the JOIDES Resolution acquired geophysical logs, cores, and installed two sub-seafloor observatories on a transect across the northern Hikurangi subduction margin. The coring and logging data provide unprecedented insights into the fault rocks entering a slow slip source region, and reveals that lithological heterogeneity and the healing characteristics of the fault rocks play a major role in shallow SSE occurrence.

The Hikurangi borehole observatories have detected pore pressure changes as a proxy for volumetric strain during several SSE s, and provide an unparalleled view of the spatio-temporal distribution of both spontaneous and dynamically triggered slow slip events near the trench.

Results from IODP borehole observatories at Hikurangi, Nankai, and Costa Rica demonstrate that such observatories provide the highest fidelity measurements currently available of offshore crustal strain, and should be installed and utilised more widely.

Streaming information

Zoom link: https://bit.ly/otagogeology