Accurate sea floor mapping: From multichannel seismic hydrophone

Abstract

Accurate sea floor maps are needed for many applications, such as geological studies, coastal safety, navigation, and climate changes, but have only been produced recently by utilizing digital multibeam technology, remotely operated vehicles, or diving in a submersible device. However, because of the cost of these operations, those maps are rare for areas that are not shallow and near the shore. The goal of this research is to investigate the feasibility of using marine seismic survey data for accurate sea floor mapping. Seismic survey data has been widely collected around the world by oil and gas companies for oil and gas exploration. The data used in this research is the multichannel marine seismic survey EW0008 in the western Atlantic Ocean obtained from the Earth Institute Marine Geoscience Data System at Columbia University. The Seismic Unix processing package from the Center of Wave Phenomena at Colorado School of Mines is used to process the EW0008 survey. By using the common midpoint gather to analyze the velocity of sound traveling between the ocean surface and floor, based on the hyperbolic move out assumption, we can precisely determine the velocity of sound to an accuracy of 1m/sec at 37.5m increment along the sail line, and determine the sea floor reflection time at 1ms time resolution. Therefore, the accuracy of sea floor mapping is approximately 0.1 percent of the water depth in this survey area.The research results show that the multichannel marine seismic survey data can be used for accurate sea floor mapping, achieving large scale sea floor coverage with an accuracy of approximately 0.1 percent. This project illustrated a creative use of the marine seismic survey data beyond its intended purposes and improved sea floor mapping accuracy and coverage significantly. It is a start of greater efforts to map Earth's sea floor.