First Results of Inaugural Deployments of the Australian National Ocean Bottom Seismograph Fleet

Abstract

The Australian National Ocean Bottom Seismograph Fleet is part of AuScope’s Australian Geophysical Observing System (AGOS) — an initiative of the Australian Government funded through the Education Investment Fund. These instruments will greatly contribute to the understanding of the crust beneath oceanic basins surrounding Australia. In 2014–15 the Australian National OBS Fleet was utilised by the petroleum industry on a number of seismic surveys. High-quality data were recorded at all OBS deployment sites, often to offsets sufficiently large to detect Pn phases — refractions from the upper mantle. Analysis of earthquake data recorded during marine seismic surveys suggests strong interaction between anthropogenic signals (airgun source, vessel noise) and the natural environment, and allows arguing that in some instances earthquake energy contaminates marine reflection data in the frequency pass-band needed for petroleum exploration. Recording earthquake and airgun signals at fixed locations opens up a completely new possibility for calibration and comparison of those signal strengths and spectral compositions.