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doi:10.14379/iodp.sp.362add.2016

International Ocean Discovery Program
Expedition 362 Scientific Prospectus Addendum

The Sumatra Subduction Zone:

The role of input materials in shallow seismogenic slip and forearc plateau development1


Lisa C. McNeill

Co-Chief Scientist

Ocean and Earth Science

National Oceanography Centre Southampton

University of Southampton

Southampton S014 3ZH

United Kingdom

lcmn@noc.soton.ac.uk

Brandon E. Dugan

Co-Chief Scientist

Department of Geophysics

Colorado School of Mines

Golden CO 80401

USA

dugan@mines.edu

Katerina E. Petronotis

Expedition Project Manager/Staff Scientist

International Ocean Discovery Program

Texas A&M University

1000 Discovery Drive

College Station TX 77845

USA

petronotis@iodp.tamu.edu

Published July 2016

See the full publication in PDF.

Introduction

Due to the availability of new site survey data and previous changes that defined proposed Sites SUMA-11C and SUMA-12A as the primary sites for Expedition 362, two new proposed alternate sites have been selected: SUMA-23A and SUMA-24A.

This addendum provides the scientific objectives for proposed Sites SUMA-23A and SUMA-24A, regional and detailed maps, and seismic profiles for the two sites. The site priorities and drilling and coring strategy remain unchanged from the original Expedition 362 Scientific Prospectus. The operations time estimates for all alternate sites are presented.

The new proposed alternate Sites SUMA-23A and SUMA-24A are located above Fracture Zone 7B, which is located south of the current primary and alternate sites. The sites are located close to the epicenter of one of the 2012 Mw >8 earthquakes. These sites are still part of the input section to the southern 2004 earthquake rupture region of the subduction zone.

Proposed Site SUMA-23A provides a section of Unit 1 (thin trench wedge) and a significant part of Unit 2 (Bengal-Nicobar submarine fan deposits and interbedded hemipelagite) overlying Fracture Zone 7B and includes sampling of 10 m of basement atop the basement high.

Proposed Site SUMA-24A provides a section of Unit 1 (thin trench wedge) and a thinner part of Unit 2 (Bengal-Nicobar submarine fan deposits and interbedded hemipelagite) than proposed Site SUMA-23A, which overlies Fracture Zone 7B, and includes sampling of 10 m of basement atop the basement high.

The new site survey data were acquired on board the Schmidt Ocean Institute (CA, USA) research vessel (R/V) Falkor in 2015 during the MegaTera experiment, an international project between the Earth Observatory Singapore (EOS), the Indonesian Institute of Sciences, Schmidt Ocean Institute (SOI), and Institut de Physique du Globe de Paris (France). SOI provided the R/V Falkor for the experiment, and EOS funded the rental of the seismic equipment.


1McNeill, L., Dugan, B., and Petronotis, K., 2016. Expedition 362 Scientific Prospectus Addendum: the Sumatra subduction zone. International Ocean Discovery Program. http://dx.doi.org/‚Äč10.14379/‚Äčiodp.sp.362add.2016