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Susan Rhea

Publications and source records attributed to Susan Rhea.

23 records · Page 2Linked to original sources
USGS1994

Map showing locations of geophysical survey and modeling lines in the vicinity of New Madrid, Missouri

This is one of a series of five seismotectonic maps of the seismically active New Madrid area in southeast Missouri and adjacent parts of Arkansas, Kentucky, and Tennessee (table 1). We cannot legibly show all the seismotectonic data on a single map, therefore each of the five maps in this series groups a different type of related information. Rhea and others (1994) summarized the background and purpose of the seismotectonic map folio.

Missouri↗
USGS1994

Map showing structure of the Mississippi Valley Graben in the vicinity of New Madrid, Missouri

This is one of a series of five seismotectonic maps of the seismically active New Madrid area in southeast Missouri and adjacent parts of Arkansas, Kentucky, and Tennessee (table 1). We cannot legibly show all the seismotectonic data on a single map, therefore each of the five maps in this series groups a different type of related information. Rhea and others (1994) summarized the background and purpose of the seismotectonic map folio. The different types of data shown on this map are described in table 2. Except for a few exposed faults, all structures shown on the map are in Paleozoic sedimentary rocks of the midcontinent or underlying metamorphic and igneous basement rocks of presumed Precambrian age (Dart, 1992; Muehlberger, 1992). Edge of Mississippi Embayment, as shown on the map, marks the contact between gently dipping, exposed Paleozoic rocks to the northwest (Anderson and others, 1979) and unconformably overlying, flat or gently dipping Mesozoic and Cenozoic strata of the embayment to the southeast.

Missouri↗
USGS1994

Map showing surficial and hydrologic features in the vicinity of New Madrid, Missouri

This is one in a series of five seismotectonic maps of the seismically active New Madrid area in southeast Missouri and adjacent parts of Arkansas, Kentucky, and Tennessee (table 1). ). We cannot legibly show all the seismotectonic data on a single map, therefore each of the five maps in this series groups a different type of related information. Rhea and others (1994) summarized the background and purpose of the seismotectonic map folio. To aid in locating small features mentioned in the text and tables we have divided the map area into 16 tracts (fig. 1); some of the small features are identified by tract number. The focus of this map is earthquake effects in the New Madrid area. The first part of the discussion is a description of some superficial effects of three great earthquakes that struck the map area during the winter of 1811-12 (Nuttli, 1973). Next, we discuss other possible records of recent deformation that may have bearing on the assessment of seismic hazards. Finally, some features of uncertain origins are discussed; these have unknown bearing on hazard assessment. Some swampy or flooded areas, locally called sunklands, are discussed in two places because two of the sunklands formed or enlarged during the 1811-12 earthquakes, whereas the others are of uncertain origins.

Missouri↗
USGS1983

Studies related to the Charleston, South Carolina, earthquake of 1886 — Tectonics and seismicity

Since 1973, the U.S. Geological Survey (USGS), with support from the Nuclear Regulatory Commission, has conducted extensive investigations of the tectonic and seismic history of the Charleston, S.C., earthquake zone and surrounding areas. The goal of these investigations has been to discover the cause of the large intraplate Charleston earthquake of 1886, which dominates the record of seismicity in the Southeastern United States, through an understanding of the historic and modern seismicity at Charleston and of the tectonic setting of the seismicity. This goal is being pursued to evaluate the potential for additional large earthquakes in the Charleston area and surrounding regions and to determine whether the Charleston area differs tectonically in any significant fashion from other parts of the Southeastern United States. An understanding of the specific cause for the 1886 event and of the regional distribution of any structures that are generically related to or geometrically and mechanically similar to the source structure is essential for evaluation of seismic hazards throughout the Southeast. The results given herein represent significant progress toward understanding the tectonic setting of the Charleston-area seismicity. Several chapters in the volume address the distribution and origin of pre-Cretaceous rocks and structures beneath Coastal Plain sediments in the Charleston area and regionally beneath the southern Atlantic Coastal Plain and adjacent Continental Shelf. The modern seismicity at Charleston is occurring at depths equal to or greater than the known extent of these older structures, and rejuvenation of an older fault in the modern stress field is a possible cause of the seismicity. Accordingly, several chapters discuss the possible relationships of the various pre-Cretaceous structures to faults identified near Charleston that have a known Cretaceous and Cenozoic movement history and to the historic and instrumentally recorded seismicity. However, at the present time, none of the young structures can be related unequivocally to the seismicity because earthquake fault-plane solutions and hypocenter distributions do not agree with the locations and orientations of these structures. Therefore, a major emphasis of continuing USGS investigations near Charleston will be to identify additional faults, if any exist, to delineate fault movement histories, and to further refine earthquake locations, focal mechanisms, and related seismological interpretations.

Florida, Georgia, South Carolina↗