Because undercompacted shale has slow seismic velocity and low density, a high pressure zone can also be identified from sonic and density logs.<ref name=pt03r33>Magara, K., 1978, Compaction and fluid migration: New York, Elsevier Scientific Publishing Company, 319 p.</ref> | Because undercompacted shale has slow seismic velocity and low density, a high pressure zone can also be identified from sonic and density logs.<ref name=pt03r33>Magara, K., 1978, Compaction and fluid migration: New York, Elsevier Scientific Publishing Company, 319 p.</ref> |