HR: 1340h
AN: S13B-1059    [Abstracts]
TI: Study of the Northern sea of Okhotsk Tectonic Zone Using Common Depth Point (CDP) Exploration Profiles
AU: * Chalyy, K
EM: GTON@emsd.magadan.ru
AF: Magadan EMSD, Scouridina 6B, Magadan, 685000 Russian Federation
AU: Sedov, B
EM: sedov@neisri.magadan.ru
AF: Magadan EMSD, Scouridina 6B, Magadan, 685000 Russian Federation
AB: The study of seismo-tectonics in oceanic regions requires special scientific research. At the same time, many offshore regions that are oil-bearing by occur in the zones of high seismic activity, and are covered by the dense net of seismic profiles. These profiles are done by the method of common depth point (CDP). For example, the northern part of the Sea of Okhotsk is characterized by high seismic activity, and more than 50 000 km of seismic CDP profiles of have been done. The analysis of seismic sections has shown that modern active faults have characteristic features which allow to determine their major parameters. On the non-migrated reflection sections, faults are marked by the numerous diffracted waves. The active faults cross the layered sedimentary stratum from the sea bottom and are traced into the acoustic basement. The active tectonic faults are almost always grouped into zones up to a kilometer in width. The dip of the fault planes are steep; and as a rule they are located subparallel to each other. Within the zones of tectonic faults, displacements of the surface of the acoustic basement have a step-like character. Separate portions of the tectonic zones are represented by crush zones up to 200 m wide. At present, the most active tectonic faults are characterized by only horizontal displacement and are not reflected in the sea bottom relief. The most active tectonic zones are spread in latitudinal direction and have the length up to 150-350 km. The maximum amplitude of vertical displacements of the acoustic basement reaches 8-10 km. Such zones are marked by gradients in the gravity field. The length of tectonically active zones and the amplitudes of vertical displacement are the integral mark of seismicity. It makes possible to estimate the maximum possible energy of the earthquakes in the future. Besides the active faults, breaks in acoustic basement and within the low structural stages of the sedimentary stratum are distinguished on the reflection seismic sections of CDP. These faults are not active at the present time.
DE: 8000 STRUCTURAL GEOLOGY (New field, replaces single entry 8165)
DE: 8100 TECTONOPHYSICS
DE: 7200 SEISMOLOGY
SC: Seismology [S]
MN: 2004 AGU Fall Meeting