FUNDAMENTAL AND APPLIED RESEARCH IN SEISMOLOGY IN ALASKA.
Final rept., 1 Jul 64-31 Dec 65.
ALASKA UNIV COLLEGE GEOPHYSICAL INST
Pagination or Media Count:
A catalogue of earthquakes using all available sources was compiled, including earthquakes up to summer 1965. Energy release of the Aleutian Chain, Alaska and the southeast was studied and mapped. About one half of the total energy was released along the coastal region of the Alaska mainland. There was also significant activity along a branch reaching into the Fairbanks area including three shocks with magnitudes in the 7 12 range since 1904. Fault plane solutions from the main and a series of aftershocks of the March 28, 1964 earthquake indicated that the predominant compressional force system was more or less directed perpendicular to the range. There was strong indication that the March 28, 1964 Alaskan earthquake and the major aftershocks of U.S.C. and G.S. magnitude or 5.5 except for the first 24 hours and located on the continental shelf were possibly triggered by low ocean tide loads. The observation was consistent with the force system derived from fault plane solutions and the land uplift and subsidence which occurred during the main shock. The pressure variation during an ocean tide cycle on the bottom of the shelf area was considered significant in carrying the last part of the stress-strain curves of the rock into the strain softening region towards failure. During the Longshot experiment, not only clear compressional P waves but also outstandingly clear PcP waves have been observed in the distance range 1800 to 2600 km. Author
- Geology, Geochemistry and Mineralogy