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Meridee Jones-Cecil

Publications and source records attributed to Meridee Jones-Cecil.

7 recordsLinked to original sources
USGS1994

Faults and structure in the Pierre Shale, central south Dakota

Numerous faults observed at the surface and (or) determined by geometric and geophysical methods to be present as much as several hundred meters below the surface (near-surface faults) have been mapped in a 2,000-km 2 area west of Pierre, S. Dakota. Many of these faults surround an east-west-trending structural high that has been mapped on the lower part of the Virgin Creek Member of the Pierre Shale. Generally, the geometry and displacement of many of the faults precludes slumping from surficial erosion as a mechanism to explain the faults. Seismic-reflection data indicate that several of the faults directly overlie faults in Precambrian basement that have cumulative vertical displacements of as much as 340 m. The structural high is interpreted to have been uplifted by displacements along faults that cut Upper Cretaceous sedimentary rocks. Recent low-level seismicity and fluvial-geomorphic studies of stream patterns, gradients, and orders suggest that rejuvenation of drainages may be taking place as a result of rebound or other tectonic activity. The studies indicate that repeated uplift and subsidence may have been the cause of extensive faulting mapped in the Pierre Shale since its deposition in Cretaceous time. Surficial fault displacements that cause damage to engineered structures are thought to be the result of construction-induced rebound in the Pierre Shale, although tectonic uplift cannot be ruled out as a cause.

Special Paper of the Geological Society of America↗
USGS1981

Pattern-recognition program modified and applied to southeastern United States seismicity

The pattern-recognition technique of Bongard and others (1966), Gelfand and others (1976), and Briggs and others (1977) was modified and applied in Southeastern United States to try to detect combinations or interactions of geologic, geophysical, and topographic parameters characteristic of areas with moderate and large earthquakes. The modification involved replacing the operator-defined criteria for significance of association of parameters and earthquakes with statistical estimates of significance. This was done in order to decrease the probability of random associations and to increase the flexibility of the pattern-recognition technique. The binomial distribution was used to determine the probability that each particular association could have occurred by chance. Bonferroni's inequality was invoked to determine a conservative significance level for each of the binomial tests. However, without being able to quantify the dependence among the associations, it is not possible to statistically evaluate the group of binomial tests as a whole. Preliminary results identify four independent associations characterizing spatially independent earthquake epicenters, or "dangerous" points, and seven independent associations characterizing the intervening "safe" points. When all points were reclassified using these traits, all epicenters were correctly classified as dangerous. In addition, three "safe" points were reclassified as dangerous and appear to be potential sites for future earthquakes. However, it is not possible to determine the degree of dangerousness of the points using this reclassification scheme. Two dangerous zones emerge in the northeast and southwest portions of the study area. Epicenters outside of these zones, including those of the large historic earthquakes (MMI > VIII) in Giles County, Virginia, and Charleston, South Carolina, have not been well characterized by the significant associations and may have fundamentally different causes.

southeastern United States↗