Ocean bottom seismometer data at Hess Deep, acquired during R/V Maurice Ewing expedition EW0305 (2003)

This cruise acquired 16 scarp-parallel MCS profiles and 7 scarp-perpendicular MCS profiles as well as OBS data across the Hess Deep, near the Pacific-Cocos-Nazca triple junction, eastern Pacific Ocean. A companion program, EW0410, took place in October-November 2004 along the Blanco Transform Fault. The primary objective of the cruise was to make a direct link between the geologic and seismic structure of intermediate-spreading oceanic crust. Questions that were to be addressed by the seismic experiments include: 1) Is there a correlation between seismic and geologic structure at the Blanco Transform? 2) Is the seismic structure at the Blanco Transform typical of intermediate-spreading crust? 3) What is the evolution of the shallow velocity structure from zero-age rise-axis crust to the 0.65-1.65 Ma crust in the study areas? Funding was provided by NSF grants OCE-0137286.

本次科考航次在东太平洋太平洋-科科斯-纳斯卡三联点附近的赫斯深渊区域，采集了16条平行于陡崖的多道地震（Multi-channel Seismic, MCS）剖面与7条垂直于陡崖的多道地震剖面，同时获取了海底地震仪（Ocean Bottom Seismometer, OBS）观测数据。配套项目EW0410于2004年10—11月沿布兰科转换断层开展。本次航次的核心科学目标是直接建立中等扩张速率洋壳的地质结构与地震结构之间的关联。本次地震实验拟解决的科学问题如下：1）布兰科转换断层处的地震结构与地质结构是否存在相关性？2）布兰科转换断层处的地震结构是否符合中等扩张速率洋壳的典型特征？3）研究区域内，从零年龄扩张轴洋壳至0.65~1.65百万年（Ma）洋壳的浅部速度结构演化规律如何？本研究获美国国家科学基金会（National Science Foundation, NSF）OCE-0137286项目资助。