HR: 0800h
AN: S11B-0165    [Abstracts]
TI: Explosion Discrimination in Eastern Russia Based on Amplitude Ratios Obtained From Analog Records
AU: * Linkimer, L
EM: linkime1@msu.edu
AF: Michigan State University, Department of Geological Sciences, 206 Natural Science Building, East Lansing, MI 48824-1115 United States
AU: Mackey, K G
EM: mackeyke@msu.edu
AF: Michigan State University, Department of Geological Sciences, 206 Natural Science Building, East Lansing, MI 48824-1115 United States
AU: Fujita, K
EM: fujita@msu.edu
AF: Michigan State University, Department of Geological Sciences, 206 Natural Science Building, East Lansing, MI 48824-1115 United States
AB: Both earthquakes and explosions occur in much of Eastern Russia. In general, earthquakes are concentrated in broad areas related to the boundaries between the Eurasian, North American, Okhotsk, and Amur plates. On the other hand, industrial explosions are related to mining, and the constructions of roads, rails, and dams, much of which occurs in the same general area as do natural earthquakes. The published and unpublished Russian bulletins (such as those from the Yakutsk and Magadan regional networks) contain information about both earthquakes and explosions however very few events are explicitly marked as explosions in those bulletins. This results in the contamination of the earthquake catalog by explosions which can result in a misinterpretation of local tectonics, and an erroneous assessment of the natural seismic hazard in the region. As it is impractical to re-examine all analog records obtained in the past 40 years, a rapid method of discriminating between earthquakes and explosions based on the regional network bulletins is desirable. As a preliminary effort, 106 explosions and 194 earthquakes recorded at seismic stations which used SKM-3 seismometers between 1985 and 1989 were analyzed to see if a discriminant could be obtained. Information about amplitudes, arrival times, and location of earthquakes and explosions were taken from both published and unpublished bulletins of the Yakutsk and Magadan regional networks and from analog seismograms obtained in Russia. Different Sg/Pg amplitude ratios are compared from explosions and small earthquakes. The ratios calculated are: Sg (h)/Pg (z), Pg (z)/Sg (z), Sg (h)/Pg (h), and Sg (z)/Pg (h), where h is the horizontal component and z is the vertical component. All amplitude ratios are plotted against distance, and energy class of the seismic shock (K class) as calculated by station. We applied a distance correction to the ratios and found that most consistent discriminants for separating earthquakes from explosions are the amplitude ratios Pg(z)/Sg(h) and Pg(z)/Sg(z) as a function of K class. There is a tendency of the explosions to have higher values than earthquakes. More distinct separations can be found if the ratios are plotted for specific stations and specific ranges of distances. The clearest distinction occurs at distances from 100 to 300 km.
DE: 7203 Body waves
DE: 7219 Seismic monitoring and test-ban treaty verification
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
SC: Seismology [S]
MN: Fall Meeting 2005