In seismic exploration, reflected seismic energy is detected by hydrophones to produce seismograms to emphasize a dipping formation which is of interest. The seismograms are produced by directing seismic energy from an array of sources at an angle such that it will reflect vertically from the dipping...http://www.google.com.tw/patents/US4146870?utm_source=gb-gplus-share專利 US4146870 - Seismic exploration for dipping formations
