Marine Seismic Refraction Services- Brochure

SPOTLIGHTGEOPHYSICAL SERVICESFor more information, contact Spotlight Geophysical Services at info@spotlightgeo.com on the web at www.spotlightgeo.comMarine Seismic RefractionMarine seismic refraction is a method to determine the seismicP-wave velocity structure of the subsurface. The P-wave velocity isrelated to the hardness of the sub-bottommaterials and canbeusedto map the top-of-rock, determine the dredgeability of sub-bottommaterials, and identify anomalous conditions. Seismic P-waves aregenerated by a powerful airgun in the water column and propagatethrough the water and sub-bottom strata. Refracted P-waves aresensed by a hydrophone streamer and recorded by a seismograph.The data are processed to produce a continuous P-wave velocitycross-section, fromwhichgeologic interpretations andmappingaredeveloped. Marine seismic refraction applications include harbordevelopment, channel dredging, marine geotechnical assessmentsfor bridges and piers, and assessments for geologic hazards prior tohorizontaldrillingand tunneling.0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300Station (m)-60-55-50-45-40-35-30-25-20-15-10-50DepthBelowMLL(m)1500160017001800190020002100220023002400250026002700280029003000SedimentsRockP-waveVelocity(m/s)increasinghardnessWaterSedimentRock