A Response Spectral Ratio Model to Account for Amplification and Attenuation Effects in the Atlantic and Gulf Coastal Plain

2021 ◽  
Author(s):  
Martin C. Chapman ◽  
Zhen Guo
Keyword(s):  
Coastal Plain ◽  
Reference Site ◽  
Spectral Ratio ◽  
Ratio Model ◽  
Eastern United States ◽  
Gulf Coastal Plain ◽  
Ground Motion Model ◽  
Linear Behavior ◽  
Psa Response ◽  
Lg Wave

ABSTRACT We used our previously published Lg-wave spectral ratio model to develop a model of pseudospectral acceleration (PSA) response ratios at sites in the Atlantic and Gulf Coastal Plain, relative to a reference site condition defined as the mean response for site locations outside the Coastal Plain. The model is strongly dependent on sediment thickness. The results of this study can be used to predict PSA response, for linear behavior, at sites in the Atlantic or Gulf Coastal Plain with a known thickness of Coastal Plain sediment, given a ground-motion model for reference site conditions outside the Coastal Plain region of the central and eastern United States.

Burial Mounds on the Gulf Coastal Plain

1958 ◽  
Vol 23 (3) ◽  
pp. 274-284 ◽  
Author(s):  
William H. Sears
Keyword(s):  
United States ◽  
Coastal Plain ◽  
Intimate Relationship ◽  
Eastern United States ◽  
Gulf Coastal Plain ◽  
Political Structure ◽  
Social Controls ◽  
Burial Mounds

Burial mounds, with their contained structures, artifacts, burials, and the patterns of relationship between these concrete items, represent the largest recoverable body of data in the eastern United States which bears directly on problems concerned with prehistoric religion and ceremonialism. These data in turn are directly applicable, with varying levels of reliability, to problems of prehistoric social and political structure. This is possible through the predictably intimate relationship between supernatural and social controls which obtains in primitive societies.

Characterizing Fundamental Resonance Peaks on Flat-Lying Sediments Using Multiple Spectral Ratio Methods: An Example from the Atlantic Coastal Plain, Eastern United States

2021 ◽  
Author(s):  
Lisa S. Schleicher ◽  
Thomas L. Pratt
Keyword(s):  
United States ◽  
Coastal Plain ◽  
Site Response ◽  
Spectral Ratio ◽  
Atlantic Coastal Plain ◽  
Unconsolidated Sediments ◽  
Eastern United States ◽  
Fundamental Resonance ◽  
Hvsr Method ◽  
Atlantic Coastal

ABSTRACT Damaging ground motions from the 2011 Mw 5.8 Virginia earthquake were likely increased due to site amplification from the unconsolidated sediments of the Atlantic Coastal Plain (ACP), highlighting the need to understand site response on these widespread strata along the coastal regions of the eastern United States. The horizontal-to-vertical spectral ratio (HVSR) method, using either earthquake signals or ambient noise as input, offers an appealing method for measuring site response on laterally extensive sediments, because it requires a single seismometer rather than requiring a nearby bedrock site to compute a horizontal sediment-to-bedrock spectral ratio (SBSR). Although previous studies show mixed results when comparing the two methods, the majority of these studies investigated site responses in confined sedimentary basins that can generate substantial 3D effects or have relatively small reflection coefficients at their base. In contrast, the flat-lying ACP strata and the underlying bedrock reflector should cause 1D resonance effects to dominate site response, with amplification of the fundamental resonance peaks controlled by the strong impedance contrast between the base of the sediments and the underlying bedrock. We compare site-response estimates on the ACP strata derived using the HVSR and SBSR methods from teleseismic signals recorded by regional arrays and observe a close match in the frequencies of the fundamental resonance peak (f0) determined by both methods. We find that correcting the HVSR amplitude using source term information from a bedrock site and multiplying the peak by a factor of 1.2 results in amplitude peaks that, on average, match SBSR results within a factor of 2. We therefore conclude that the HVSR method may successfully estimate regional linear weak-motion site-response amplifications from the ACP, or similar geologic environments, when appropriate region-specific corrections to the amplitude ratios are used.

Allometry and Paleoecology of Medial Miocene Dwarf Rhinoceroses from the Texas Gulf Coastal Plain

Paleobiology ◽  
1982 ◽  
Vol 8 (1) ◽  
pp. 16-30 ◽  
Author(s):  
Donald R. Prothero ◽  
Paul C. Sereno
Keyword(s):  
Body Size ◽  
Coastal Plain ◽  
Sympatric Species ◽  
High Plains ◽  
Gulf Coastal Plain ◽  
Canine Tooth ◽  
Positive Allometry ◽  
Mammalian Faunas ◽  
The Common ◽  
Limb Proportions

Barstovian (medial Miocene) mammalian faunas from the Texas Gulf Coastal Plain contained four apparently sympatric species of rhinoceroses: the common forms Aphelops megalodus and Teleoceras medicornutus, a dwarf Teleoceras, and a dwarf Peraceras. Previous work has suggested positive allometry in tooth area with respect to body size in several groups of mammals, i.e., larger mammals have relatively more tooth area. However, dwarfing lineages were shown to have relatively more tooth area for their body size. Our data show no significant allometry in post-canine tooth area of either artiodactyls or ceratomorphs. Similarly, dwarf rhinoceroses and hippopotami show no more tooth area than would be predicted for their size. Limbs are proportionately longer and more robust in larger living ceratomorphs (rhinos and tapirs) than predicted by previous authors. Limb proportions of both dwarf rhinoceroses and dwarf hippopotami are even more robust than in their living relatives.The high rhinoceros diversity reflects the overall high diversity of Barstovian faunas from the Texas Gulf Coastal Plain. The first appearance of several High Plains mammals in these faunas indicates “ecotone”-like conditions as faunal composition changed. Study of living continental dwarfs shows that there is commonly an ecological separation between browsing forest dwarfs and their larger forebears, which are frequently savannah grazers. This suggests that the dwarf rhinoceroses might have been forest browsers which were sympatric with the larger grazing rhinos of the High Plains during the Barstovian invasion. The continental dwarf model also suggests that insular dwarfism may be explained by the browsing food resources that predominate on islands.

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