Session 9: Seismology: Predicting Strong Ground Motion for Design

Location

St. Louis, Missouri

3-11-1991

3-15-1991

Abstract

The least squared, the major axis and the reduced major axis criterion are used to deduce a statistical relation between magnitude, mbLg, and intensity, I, for the earthquakes-in southeastern United States. Based on a catalog of 162 events during 1833 to 1987, with magnitudes between 1.1 and 6.9 and intensities between II and X, it is shown that the reduced major axis criterion produces: mbLg = (0.656 ± 0.058)*I + (0.402 ± 0.178), which is the best predictor equation of magnitude for the upper range of the observed intensities. The predictor equations based on the least squared and major axis criterion are: mbLg = (0.441 ± 0.038)*I + (1.359 ± 0.176) and mbLg = (0,544 ± 0.047)*I + (0.898 ± 0.424), respectively; the least squared equation is a better predictor for the lower range of the observations and the major axis equation yields predictions which are between the predictions from the other two equations. In mid-range of the observed data all three equations predict nearly the same results. A set of three similar equations are found between intensity, I, and magnitude mbLg. The effects of various conversion methods on values of a and b in the frequency-magnitude equation log N= a + b*mbLg and values of a' and b' in the frequency-intensity relation log N= a' + b'*I are negligible. Three new catalogs, with 2245 events in each were formed; in the new catalogs if the intensity or the magnitude of an event was missing it was estimated based on the above equations; then, the least squared technique was used to calculate the coefficients a, b, a', and b'; the unnormalized values of the coefficients are: a = 4.105 ± 0.144, b = -0.591 ± 0.035, a' = 3.941 ± 0.199, and b' = -0.400 ± 0.033, respectively.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Meeting Name

Second Conference

Publisher

University of Missouri--Rolla

3-11-1991

Final Version

Document Type

Article - Conference proceedings

text

English

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Mar 11th, 12:00 AM Mar 15th, 12:00 AM

Statistical Relations Between Intensity and Magnitude of Southeastern United States Earthquakes

St. Louis, Missouri

The least squared, the major axis and the reduced major axis criterion are used to deduce a statistical relation between magnitude, mbLg, and intensity, I, for the earthquakes-in southeastern United States. Based on a catalog of 162 events during 1833 to 1987, with magnitudes between 1.1 and 6.9 and intensities between II and X, it is shown that the reduced major axis criterion produces: mbLg = (0.656 ± 0.058)*I + (0.402 ± 0.178), which is the best predictor equation of magnitude for the upper range of the observed intensities. The predictor equations based on the least squared and major axis criterion are: mbLg = (0.441 ± 0.038)*I + (1.359 ± 0.176) and mbLg = (0,544 ± 0.047)*I + (0.898 ± 0.424), respectively; the least squared equation is a better predictor for the lower range of the observations and the major axis equation yields predictions which are between the predictions from the other two equations. In mid-range of the observed data all three equations predict nearly the same results. A set of three similar equations are found between intensity, I, and magnitude mbLg. The effects of various conversion methods on values of a and b in the frequency-magnitude equation log N= a + b*mbLg and values of a' and b' in the frequency-intensity relation log N= a' + b'*I are negligible. Three new catalogs, with 2245 events in each were formed; in the new catalogs if the intensity or the magnitude of an event was missing it was estimated based on the above equations; then, the least squared technique was used to calculate the coefficients a, b, a', and b'; the unnormalized values of the coefficients are: a = 4.105 ± 0.144, b = -0.591 ± 0.035, a' = 3.941 ± 0.199, and b' = -0.400 ± 0.033, respectively.