ALEUTIAN ISLANDS EXPERIMENT OCEAN-BOTTOM SEISMOGRAPHIC EXPERIMENTS
Abstract
The crustal structure across Amchitka was determined from two in-line reversed-refraction profiles located northeast and southwest of Amchitka. Both profiles employed 10 Ocean-Bottom Seismographs (OBS) spaced at 20-km intervals and 5-ton shots detonated at 20-km intervals off each end of the OBS line. Traveltimes were corrected to a reference plane 4.5 km below sea level to minimize lateral velocity variations associated with the large changes in water depth in the area. Depth to the Moho along the profile was determined from first arrivals using standard refraction analysis, wavefront methods, the time- term method and model perturbation techniques. Calculations show the Moho refractor to be dipping towards Amchitka with the root of the structure located 60 km north of Amchitka under Semisopochnoi Island. The Moho velocity is 8.1 km/sec in the area. Nearly all of the first arrivals were Moho refractions; therefore, digital techniques were employed to enhance the capability of picking secondary arrivals in order to obtain upper crustal velocity information. In general, secondary arrivals were difficult to identify, and although some apparent velocity measurements were obtained, the information could not be directly incorporated into the crustal model.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 31, 1968
- Accession Number
- AD0694099
Entities
People
- A. Frank Linville
- A. Ronald Mendina
- Gary D. Mcneely
- R. Fred Howard
- Ronald D. Bauer
Organizations
- Texas Instruments