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

Meridee Jones-Cecil; Russell L. Wheeler; James W. Dewey

doi:10.3133/ofr81195

Home/Archive/USGS

USGS · ofr81195

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

Meridee Jones-Cecil·Russell L. Wheeler·James W. Dewey

View original source ↗Read source document ↗Export metadata ↓

Abstract

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.

Explore related subjects

Open-File Report Report

Source-reported bounding extent: 31.466153715024294° to 38.85682013474361° latitude; -84.28710937499999° to -75.673828125° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Meridee Jones-Cecil, Russell L. Wheeler, James W. Dewey. 1981. Pattern-recognition program modified and applied to southeastern United States seismicity. https://doi.org/10.3133/ofr81195

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

ECCOE Landsat quarterly calibration and validation report—Quarter 2, 2026

Open-File Report↗

USGS2026

ECCOE Landsat quarterly calibration and validation report—Quarter 1, 2026

Executive Summary The U.S. Geological Survey Earth Resources Observation and Science Calibration and Validation (Cal/Val) Center of Excellence (ECCOE) focuses on improving the accuracy, precision, calibration, and product quality of remote-sensing data, leveraging years of multiscale optical system geometric and radiometric calibration and characterization experience. The ECCOE Landsat Cal/Val Team continually monitors the geometric and radiometric performance of active Landsat missions and makes calibration adjustments, as needed, to maintain data quality at the highest level. This report provides observed geometric and radiometric analysis results for Landsats 8 and 9 for quarter 1 (January–March) of 2026. All data used to compile the Cal/Val analysis results presented in this report are freely available from the U.S. Geological Survey EarthExplorer website: https://earthexplorer.usgs.gov . One specific activity that the ECCOE Landsat Cal/Val Team closely monitored was a Landsat 8 Thermal Infrared Sensor encoder alerts anomaly. On March 18, 2026, the Thermal Infrared Sensor instrument’s mechanism control electronics board reset, driving several parameters to default power-on values. Subsequent telemetry and analysis determined that no persistent hardware misconfiguration was present and no radiometric or geometric degradation was observed.

Open-File Report↗

USGS2026

Floods of June 20–July 6, 2024, in the Big Sioux River, Rock River, Little Sioux River, Ocheyedan River, and Floyd River Basins, northwestern Iowa

Major flooding occurred on June 20–July 6, 2024, in northwestern Iowa affecting the Big Sioux, Rock, Little Sioux, Ocheyedan, and Floyd River Basins. Heavy rain fell in northwestern Iowa, southwestern Minnesota, and southeastern South Dakota on June 20–22, 2024. Parts of northwestern Iowa recorded 2–6 inches of rainfall and localized amounts exceeding 12 inches. A maximum peak-of-record streamflow of 175,000 cubic feet per second at the U.S. Geological Survey streamgage Big Sioux River at Akron, Iowa (06485500), was recorded on June 22, 2024, and had an annual exceedance probability range of 0.2–0.49 percent. High-water marks were measured at four locations along the Big Sioux River between U.S. Interstate 29 at Sioux City, Iowa, upstream to Iowa Highway 10 north of Hawarden, Iowa, a distance of 75.7 river miles. A maximum peak-of-record streamflow of 157,000 cubic feet per second at the U.S. Geological Survey streamgage Rock River near Rock Valley, Iowa (06483500), was recorded on June 22, 2024, and had an annual exceedance probability of less than 0.2 percent. High-water marks were measured at eight locations along the Rock River between County Road B30 east of Hudson, South Dakota, upstream to Iowa Highway 9 at Rock Rapids, Iowa, a distance of 39.3 river miles. A maximum peak-of-record streamflow of 63,000 cubic feet per second at the U.S. Geological Survey streamgage Little Sioux River at Correctionville, Iowa (06606600), was recorded on June 24, 2024, and had an annual exceedance probability range of 0.2–0.49 percent. High-water marks were measured at 11 locations along the Little Sioux River between Iowa Highway 31 west of Correctionville, Iowa, upstream to U.S. Highway 18 north of Spencer, Iowa, a distance of 134.8 river miles. A maximum streamflow of 24,500 cubic feet per second at the U.S. Geological Survey streamgage Ocheyedan River near Spencer, Iowa (06605000), was recorded on June 22, 2024, and had an annual exceedance probability range of 0.2–0.49 percent. High-water marks were measured at three locations along the Ocheyedan River between County Road M38 west of Spencer, Iowa, upstream to U.S. Highway 18 west of Everly, Iowa, a distance of 12.8 river miles. A maximum streamflow of 41,000 cubic feet per second at the U.S. Geological Survey streamgage Floyd River at Alton, Iowa (06600100), was recorded on June 22, 2024, and had an annual exceedance probability range of 1–1.99 percent. High-water marks were measured at six locations along the Floyd River between Iowa Highway 3 at Le Mars, Iowa, upstream to Iowa Highway 10 at Alton, Iowa, a distance of 27.5 river miles. The high-water marks were used to develop flood profiles for the Big Sioux, Rock, Little Sioux, Ocheyedan, and Floyd Rivers.

Iowa, Minnesota, South Dakota↗