Unique common mid-point (cmp) navigation for multi-channel seismic data collected by the U.S. Geological Survey on U.S. Atlantic Seaboard in 2014 (Geographic, WGS84, point shapefile 2014-011-FA_mcscmp.shp)

In summer 2014, the U.S. Geological Survey conducted a 21-day geophysical program in deep water along the Atlantic continental margin by using R/V Marcus G. Langseth (Field Activity Number 2014-011-FA). The purpose of the seismic program was to collect multichannel seismic reflection and refraction data to determine sediment thickness. These data enable the United States to delineate its Extended Continental Shelf (ECS) along the Atlantic margin. The same data can also be used to understand large submarine landslides and therefore assess their potential tsunami hazard for infrastructure and communities living along the eastern seaboard. Supporting geophysical data were collected as marine magnetic data, gravity data, 3.5-kilohertz shallow seismic reflections, multibeam echo sounder bathymetry, and multibeam backscatter. The survey was conducted from water depths of approximately 1,500 meters to abyssal seafloor depths greater than 5,000 meters. Approximately 2,761 kilometers of multi-channel seismic data was collected along with 30 sonobuoy profiles. This field program had two primary objectives: (1) to collect some of the data necessary to establish the outer limits of the U.S. Continental Shelf, or Extended Continental Shelf, as defined by Article 76 of the United Nations Convention of the Law of the Sea and (2) to study the sudden mass transport of sediments down the continental margin as submarine landslides that pose potential tsunamigenic hazards to the Atlantic and Caribbean coastal communities.2014年夏季，美国地质调查局（U.S. Geological Survey）使用“马库斯·G·兰塞斯号”（R/V Marcus G. Langseth）科考船（野外活动编号：2014-011-FA），沿大西洋大陆边缘深水区开展了为期21天的地球物理探测工作。本次地震探测任务旨在采集多道地震反射与折射数据，以测算沉积层厚度。此类数据可助力美国划定其沿大西洋大陆边缘的外大陆架（Extended Continental Shelf, ECS）范围，同时也可用于研究大型海底滑坡，进而评估其对美国东海岸沿岸基础设施与社区构成的潜在海啸灾害风险。本次任务同步采集了配套地球物理数据，包括海洋磁力数据、重力数据、3.5千赫兹浅地层地震反射数据、多波束测深仪水深测量数据以及多波束反向散射数据。 本次探测的作业水深范围约为1500米至超过5000米的深海海底，共采集了约2761千米的多道地震数据，以及30条声呐浮标剖面数据。 本次野外作业设有两项核心目标：其一，依据《联合国海洋法公约》第七十六条相关定义，采集划定美国大陆架（即外大陆架）外部界限所需的部分数据；其二，研究沿大陆边缘向下的沉积物突发性大规模运移现象——即海底滑坡，这类滑坡会对大西洋及加勒比海沿岸社区构成潜在的致灾海啸风险。