Download or read book Comprehensive Study of the Seismotectonics of the Aleutian Arc. Annual Progress Report, March 1, 1976--February 28, 1977 written by and published by . This book was released on 1977 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Seismological, volcanological, and geodetic research supported by ERDA has contributed to knowledge of the seismotectonics of the Aleutian Island arc. Some of the results of research supported wholly or in part by ERDA have been presented in three papers: The Alaska-Aleutian Trench-Volcano Gap: Facts, and Speculations on the Role of Terrigenous Sediments on the Subduction Process; Aleutian Benioff Zone Morphology and Some Plate Tectonic Implications; and Aleutian Volcanoes as Indicators of the Regional Stress Field - Aleutians and Alaska. A catalogue of the Shumagin Islands seismicity which shows the activity of the past three years in annual and quarterly intervals is nearing completion. Focal mechanism studies of Aleutian/Alaskan earthquakes have continued. The results of 13 new solutions are presented in this report. A statistical study of Aleutian earthquakes was made to evaluate the probability of a major or great earthquake occurring within the Shumagin gap. This study concludes that it is very likely that an earthquake larger than magnitude seven will occur and that the probability that it will be larger than magnitude eight is significant. Finally, a study of surface wave dispersion to examine crust and upper mantle structure in the Pacific and Aleutian basins has begun.