NanTroSEIZE Stage 3: NanTroSEIZE plate boundary deep riser 2
Lead Research Organisation:
University of Southampton
Department Name: Sch of Ocean and Earth Science
Abstract
Subduction zones, where two lithospheric plates converge, generate the largest magnitude earthquakes on Earth. These great earthquakes commonly generate tsunami waves that impact coastal regions both local to the earthquake as well as distant communities. The 2011 Tohoku Oki and 2004 Indian Ocean earthquakes and corresponding tsunamis provide recent dramatic examples of the impact of these hazards.
Understanding of both the earthquake process and tsunami generation has significantly advanced in the last few decades with improvements in the technology for recording earthquake waves and remote study of the subsurface. However, opportunities to directly sample and measure the physical properties within the fault zones where these large earthquakes are generated are rare and require substantial resources.
The Nankai subduction zone of Japan has a long record of past earthquakes and tsunamis and is the most widely studied, and probably the best understood, subduction zone in the world. However, the challenge of directly sampling and monitoring the earthquake-generating fault system is yet to be achieved and the process of earthquake initiation and rupture is still relatively poorly understood.
The NanTroSEIZE experiment has been launched within the Integrated Ocean Drilling Program (IODP) specifically to sample, measure and monitor all parts of the subduction zone fault system, including the deeper parts (~6-7 km below the seafloor) of the system where the earthquake rupture takes place. The experiment is a long-term project staged over a period of years. The previous stages have targeted 10 different sites, each exploring a different part of the subduction system to build up a 2-D profile of the incoming rock formations and the deformation they undergo during subduction.
IODP Expedition 338, the expedition that this proposal relates to, is the second expedition of Stage 3 and will employ riser drilling to extend and case an existing borehole to a target depth of 3600 m below the seafloor in preparation for the final leg that will target the earthquake-generating fault.
A variety of methods will be used to measure sediment, rock and fault properties during Expedition 338 at a site located above the earthquake-generating part of the subduction zone:
- Samples of borehole sediments and rocks;
- Measurements of sediment-rock properties from tools in the borehole;
- In situ measurements of properties, such as pressure of fluids within the sediments and the magnitude of the strain that the rocks-sediments are under as the two tectonic plates converge;
- Preparation of the borehole for future drilling to greater depths.
The requested funds would enable the proponent to join the Core Log Seismic Integration team. Daily watchkeeping and research duties will include quality control of newly acquired data, making preliminary observations and interpretations, discussing results with other participants and contribution to the writing of the initial results.
Research interests of the proponent focus on investigating the physical properties (e.g. density, porosity) of fault structures within the prism interior. By comparing the properties of the faults located on further from the subduction zone to those within the zone of active deformation it will be possible to establish how these systems evolve through time. Determining whether the properties of these faults change gradually or abruptly will provide insights into the evolution of these systems. The data collected on this cruise will also be incorporated into the proponent's ongoing research to investigate methods of tying direct observations made at boreholes to more laterally extensive subsurface imaging data. This will provide a greater understanding about the whole subduction zone system (as well as other global subduction zones) in areas that do not benefit from direct observations.
Understanding of both the earthquake process and tsunami generation has significantly advanced in the last few decades with improvements in the technology for recording earthquake waves and remote study of the subsurface. However, opportunities to directly sample and measure the physical properties within the fault zones where these large earthquakes are generated are rare and require substantial resources.
The Nankai subduction zone of Japan has a long record of past earthquakes and tsunamis and is the most widely studied, and probably the best understood, subduction zone in the world. However, the challenge of directly sampling and monitoring the earthquake-generating fault system is yet to be achieved and the process of earthquake initiation and rupture is still relatively poorly understood.
The NanTroSEIZE experiment has been launched within the Integrated Ocean Drilling Program (IODP) specifically to sample, measure and monitor all parts of the subduction zone fault system, including the deeper parts (~6-7 km below the seafloor) of the system where the earthquake rupture takes place. The experiment is a long-term project staged over a period of years. The previous stages have targeted 10 different sites, each exploring a different part of the subduction system to build up a 2-D profile of the incoming rock formations and the deformation they undergo during subduction.
IODP Expedition 338, the expedition that this proposal relates to, is the second expedition of Stage 3 and will employ riser drilling to extend and case an existing borehole to a target depth of 3600 m below the seafloor in preparation for the final leg that will target the earthquake-generating fault.
A variety of methods will be used to measure sediment, rock and fault properties during Expedition 338 at a site located above the earthquake-generating part of the subduction zone:
- Samples of borehole sediments and rocks;
- Measurements of sediment-rock properties from tools in the borehole;
- In situ measurements of properties, such as pressure of fluids within the sediments and the magnitude of the strain that the rocks-sediments are under as the two tectonic plates converge;
- Preparation of the borehole for future drilling to greater depths.
The requested funds would enable the proponent to join the Core Log Seismic Integration team. Daily watchkeeping and research duties will include quality control of newly acquired data, making preliminary observations and interpretations, discussing results with other participants and contribution to the writing of the initial results.
Research interests of the proponent focus on investigating the physical properties (e.g. density, porosity) of fault structures within the prism interior. By comparing the properties of the faults located on further from the subduction zone to those within the zone of active deformation it will be possible to establish how these systems evolve through time. Determining whether the properties of these faults change gradually or abruptly will provide insights into the evolution of these systems. The data collected on this cruise will also be incorporated into the proponent's ongoing research to investigate methods of tying direct observations made at boreholes to more laterally extensive subsurface imaging data. This will provide a greater understanding about the whole subduction zone system (as well as other global subduction zones) in areas that do not benefit from direct observations.
Planned Impact
Science communication and public outreach is a major component of the NanTroSEIZE project and of IODP. As a Logging/Structural Geologist, my role will be to promote the objectives, results and implication to both the scientific community and public audiences.
As a participant of the NanTroSEIZE project I will have access to data collected during the cruise as well as the wider project. This will be incorporated into my postdoctoral research project, investigating the relationship between physical properties and reflector characteristics. The project-generated results will have a direct influence on future data collection planning on convergent margins, including proposals for IODP drilling. In general, interactions with the subduction zone community will result in better-targeted proposals to test hypotheses generated by this project.
Outreach activities (e.g. National Science Week Ocean and Earth Day at the National Oceanography Centre Southampton) will engage non-scientists within the public community and inform them about the processes at subduction zones, the potential hazards, the technology being developed and applied, and how the results can be used to improve mitigation of these natural hazards.
As a participant of the NanTroSEIZE project I will have access to data collected during the cruise as well as the wider project. This will be incorporated into my postdoctoral research project, investigating the relationship between physical properties and reflector characteristics. The project-generated results will have a direct influence on future data collection planning on convergent margins, including proposals for IODP drilling. In general, interactions with the subduction zone community will result in better-targeted proposals to test hypotheses generated by this project.
Outreach activities (e.g. National Science Week Ocean and Earth Day at the National Oceanography Centre Southampton) will engage non-scientists within the public community and inform them about the processes at subduction zones, the potential hazards, the technology being developed and applied, and how the results can be used to improve mitigation of these natural hazards.
Organisations
People |
ORCID iD |
| Dean Wilson (Principal Investigator) |
