Studies with a small seismic array in east-central Minnesota
Greenhalgh SA. 1979. Studies with a small seismic array in east-central Minnesota. University of Minnesota
Relative arrival times from 120 mine blasts at distances of 80 to 350 km from the Central Minnesota Seismic Array were statistically analyzed to yield a crustal velocity-depth function for the area. A long range refraction profile, extending from the Mesabi Iron Range in northern Minnesota to the seismic array, was also carried out. A striking feature of the profile is the absence of direct P waves in the distance range 60 to 120 km, suggesting the presence of a fault or fracture zone near 60 km. Dispersion relations for the fundamental mode Rayleigh wave, observed on Mesabi mine blast record, were interpreted to reveal a 1.2 km thick surface layer of shear velocity 2.7 km/s overlying a half space of shear velocity 3.3 km/s. The geologic interpretation of the model is that of the Animikie Group metasediments overlying the Lower Precambrian gneisses and granities.
- Type
- Academic
- Authors
- Greenhalgh, S
- Date of Issue
- 1979
- Publisher
- University of Minnesota
- Units
- SACN
- Keywords
- arrays, body waves, Crust, Dissertation, Earthquakes, Elastic Waves, explosions, Geophysical Methods, Great Lakes region, Interpretation, Midwest, Minnesota, P waves, Rayleigh Waves, Refraction, S waves, seismic methods, seismographs, Seismology, Structure, surface waves, teleseismic signals, Velocity Structure