The effects of array design on acoustic data collected during marine seismic reflection surveys

Abstract

Marine seismic reflection surveys provide an abundance of acoustic data that are potentially useful for an array of analyses within and in addition to geoacoustic studies. A single cruise typically produces thousands to tens of thousands of acoustic events, with hundreds of hydrophones recording each event over towed arrays that can span up to 15 km or more. However, the structure of the airgun source arrays and the receiver arrays is typically not obvious from the data alone and the pre-processing of the data may yield misleading results if not properly accounted for. Generally, the acoustic source consists of an array of airguns configured such that the acoustic energy is focused towards the ocean floor, significantly impacting the relative intensity of the direct and reflected paths. Additionally, each array channel output typically consists of multiple hydrophone outputs, which are not individually available, averaged to generate a single channel output. Understanding the impact of these constructions is crucial for many analyses, such as mitigation of airgun pulse impacts on marine mammals. Here, we quantify the impact that these factors have on the output data and provide an analysis of this influence for an experimental case. [Work supported by ONR.]