Because of the near-surface complexity, 3D seismic data processing for imaging deep reflectors encounters significant difficulties. Conventional refraction statics interpretation methods failed because of assuming simplified velocity structures. 3D refraction tomography is a powerful tool for solving the problem in this situation. TOMO3D was successfully applied to reconstruct the near-surface velocity structures for this case. The above images show the near-surface velocity distribution at four depths.
Downward direction is the positive increase.
The surface is at a depth of about 2500 feet above the sea level. The velocity images clearly show NW-SE structural trend. A high-velocity intrusion occurs in the central area. A major fault appears at the NE corner.