Journal
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
Volume 126, Issue 5, Pages -Publisher
AMER GEOPHYSICAL UNION
DOI: 10.1029/2020JB021605
Keywords
fluids; Hikurangi margin; pore pressures; seismic tomography; slow slip events; Vp; Vs
Categories
Funding
- NSF [1551922, 1333025]
- Directorate For Geosciences
- Division Of Ocean Sciences [1551922, 1333025] Funding Source: National Science Foundation
Ask authors/readers for more resources
Researchers investigated the seismic velocity structure of the Hikurangi margin in New Zealand and discovered two high Vp/Vs anomalies, which may be related to high pore fluid pressures from subducted sediments and could trigger slow slip events. The findings suggest that subduction processes in the Hikurangi margin are highly dependent on physical features such as subducted seamounts and fluid-rich sediments.
We investigated the seismic velocity structure of the Hikurangi margin in New Zealand to uncover the physical features of the subduction zone and explore the relationships between microearthquake seismicity, seismic velocity structure, and slow slip events. Using local earthquake tomography with data collected from both temporary ocean bottom seismometers and on-land permanent seismic stations, we used the tomography code TomoFD to iteratively perform a damped least squared inversion of absolute P and S arrival times to obtain relocated hypocenters and generate 3D velocity models for Vp and Vp/Vs. The seismic tomography images show two high Vp/Vs anomalies, one offshore and adjacent to a subducted seamount and the other beneath the North Island of New Zealand. The similar to 50-km wide offshore anomaly extends similar to 10 km beneath the plate interface and lies directly beneath the area that slipped at least 50 mm during the 2 week-long 2014 slow slip event. High Vp/Vs values may be related to high pore fluid pressures from subducted sediments, and such increases in pore fluid pressures have been suggested to trigger the occurrence of slow slip events in active subduction zones. The second onshore high Vp/Vs anomaly is located in the overlying plate and subducting slab and correlates with areas suggested by other geophysical techniques to be rich in fluids. Our seismic imaging supports interpretations that subduction processes in the Hikurangi margin are highly dependent on physical features such as subducted seamounts and fluid-rich sediments.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available