IODP Exp. 362 Sumatra Seismogenic Zone - Post-cruise research

GSTDTAP

项目编号	NE/P011268/1
	IODP Exp. 362 Sumatra Seismogenic Zone - Post-cruise research
	Paola Vannucchi
主持机构	Royal Holloway, University of London
项目开始年	2017
	2017-01-15
项目结束日期	2017-12-14
资助机构	UK-NERC
项目类别	Research Grant
国家	英国
语种	英语
英文摘要	The giant 2004 Mw 9.2 Sumatra-Andaman earthquake ruptured the greatest fault length of any recorded earthquake spanning a distance of 1300 km, longer than the UK from the Shetlands to Cornwall. The rupture initiated about 30 km below the ocean floor along the megathrust that separates the Indian plate from the overlying Burma-Sunda plate. It propagated northwards for 10 minutes at a maximum speed of 2.5 km/sec. Fault slip was as large as 15 m to the west with fault-slip-linked uplift reaching 2 m. The displacement of the ocean floor was a sudden 'shock' that created the devastating tsunami waves. A comprehensive view of the variable megathrust slip characteristics and distribution was obtained by combining tsunami, seismologic and geodetic observations. In the southern Sumatra-Andaman region co-seismic slip reached the near-trench portion of the plate boundary. Three months later, in March 2005, the Mw 8.7 Nias earthquake ruptured the central portion of the Indian/Burma-Sunda megathrust. This earthquake produced a smaller, but still deadly tsunami. In the Nias segment earthquake slip concentrated below the outer forearc. The potential for seismic near-trench slip in the Sumatra-Andaman segment and the more general internal variability in rupture speed along the plate boundary has been correlated with different frictional properties of the material hosting the plate boundary interface. Megathrusts form part of the subduction conveyor belt, along which incoming sediment is ultimately transported into the zone associated with Earth's most destructive earthquakes. To assess the potential for rupture propagation near the trench the geological, physical and mechanical properties of incoming plate material should be considered together with the distribution of excess fluid pressure, the complexity of the rough plate interface geometry, and the slip deficit rate at the megathrust interface. In this study, new samples recovered by IODP Exp. 362 from incoming Indian plate sediments will be used to investigate the frictional behavior of these sediments en-route to the plate boundary interface. The UKIODP Moratorium award will be used to achieve 5 Strategic Objectives: SO 1 - identify the characteristics of the sedimentary sections to optimize the sampling strategy for friction experiments based upon onboard sedimentology, petrology, geochemistry and in-situ logging profiles. This objective will benefit from the Exp. 362 Science Party work carried out during the cruise. SO 2 - acquire a quantitative data set of the mineral assemblages, fluid permeability, and porosity for each sample. SO 3 - measure their frictional dependence on slip, slip rate, slip velocity, and normal stress by performing experiments on the collected samples under deformation conditions typical of earthquakes using the high velocity rock friction apparatus SHIVA. SO 4 - monitor gas emission, humidity, and temperature variations during friction experiments using mass spectrometry, temperature and humidity measurements with the sensors installed on the rotary shear apparatus. SO 5 - analyse the experimental fault rock material using a multidisciplinary approach that involves microstructural analysis, mineralogy, and petrology so that proxy records may be reconstructed for plate interface seismic slip. Validate these against the seismological record. The ultimate goal is to incorporate the actual physical properties of the Sumatra-Andaman incoming sedimentary section within an improved theoretical earthquake rupture propagation model. This research will develop a new approach to the assessment of extreme near-trench tsunamogenic slip based on the analysis of incoming plate sediments. This approach is also applicable to other plate-boundary megathrusts (e.g. Japan Trench, Barbados). Future studies can also consider possible lateral variations in the lithological composition of the incoming plate/subduction plate boundary material.
来源学科分类	Natural Environment Research
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/86541
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Paola Vannucchi.IODP Exp. 362 Sumatra Seismogenic Zone - Post-cruise research.2017.