Near-surface deformation in the New Madrid Seismic zone as imaged by high resolution SH-wave seismic methods

1993 ◽  
Vol 20 (15) ◽  
pp. 1615-1618 ◽  
Author(s):  
Edward W. Woolery ◽  
Ron L. Street ◽  
Zhenming Wang ◽  
James B. Harris
Keyword(s):  
High Resolution ◽  
Surface Deformation ◽  
New Madrid Seismic Zone ◽  
Seismic Zone ◽  
Sh Wave ◽  
Near Surface ◽  
Seismic Methods ◽  
New Madrid

Evidence for contemporary vertical fault displacement from precise leveling data near the New Madrid seismic zone, western Kentucky

1981 ◽  
Vol 71 (6) ◽  
pp. 1933-1942
Author(s):  
F. Steve Schilt ◽  
Robert E. Reilinger
Keyword(s):  
Surface Deformation ◽  
Apparent Movement ◽  
Normal Fault ◽  
Elastic Half Space ◽  
Focal Mechanisms ◽  
New Madrid Seismic Zone ◽  
Seismic Zone ◽  
The Times ◽  
Western Kentucky ◽  
New Madrid

Abstract Relative vertical displacements of bench marks in extreme western Kentucky have been determined by comparison of successive leveling surveys in 1947 and 1968. The resulting pattern of apparent surface deformation shows steep offset which can be closely modeled by a normal fault buried in an elastic half-space. The offset is located near the northern boundary of the Mississippi Embayment and the New Madrid seismic zone, an area where faults have previously been inferred on the basis of both geological and geophysical evidence. If the apparent movement is due to slip along a fault, several lines of evidence (regional structure, earthquake data, and lineations) suggest that the postulated fault trends NNE. Thirteen earthquakes were recorded in this area between the times of leveling; focal mechanisms exist for three of these. The nearest of these three focal mechanisms to the leveling offset implies normal faulting. The magnitude of the earthquake, however, appears to be too small to account for the amount of slip required by the fault model. Thus the apparent deformation may have accumulated with several undetected small earthquakes, or gradually as aseismic creep.

High-resolution Earthquake Relocation in the New Madrid Seismic Zone

2010 ◽  
Vol 81 (2) ◽  
pp. 406-413 ◽  
Author(s):  
M. Dunn ◽  
S. Horton ◽  
H. DeShon ◽  
C. Powell
Keyword(s):  
High Resolution ◽  
New Madrid Seismic Zone ◽  
Seismic Zone ◽  
Earthquake Relocation ◽  
New Madrid

Mini-Sosie High Resolution Seismic Reflection Profiles Along the Bootheel Lineament in the New Madrid Seismic Zone

1992 ◽  
Vol 63 (3) ◽  
pp. 297-307 ◽  
Author(s):  
John L. Sexton ◽  
Harvey Henson ◽  
Paul Dial ◽  
K. Shedlock
Keyword(s):  
High Resolution ◽  
Seismic Reflection ◽  
Aerial Photographs ◽  
Source Zone ◽  
Small Scale ◽  
New Madrid Seismic Zone ◽  
Seismic Zone ◽  
Geological Structures ◽  
Linear Features ◽  
New Madrid

Abstract Results of geological and geophysical research conducted in the New Madrid seismic zone since the early 1970’s indicate that much of the seismicity of the area is associated with late Precambrian age rift-related geological structures that have been reactivated by contemporary stresses. Deep seismic reflection surveys have been used to detect and delineate deeply buried geological structures thought to be associated with the seismicity. Satellite imagery and aerial photographs have recently been used to detect a linear feature named the Bootheel lineament inferred to be the surface expression of one of the faults responsible for the 1811–1812 earthquakes. To assess the seismogenic potential of these deep structures and linear features, high resolution seismic reflection and geomorphic studies are required. In July and August, 1990, Mini-Sosie high resolution reflection surveys were conducted in the New Madrid seismic zone. A total of 23 line-kilometers of high resolution reflection data were collected at nine locations. Specific targets for the new surveys include several locations on the Bootheel lineament in the New Madrid area, its northern projection near Sikeston, Missouri, and its southern projection near Blytheville, Arkansas at locations related to the Blytheville arch. A location several kilometers south of Charleston, Missouri, was also selected. Data presented in this paper consist of 7 line-kilometers recorded at locations on or close to the Bootheel lineament near New Madrid, Missouri, Hayti, Missouri, and Blytheville, Arkansas. Numerous small-offset faults, channels and other structures in Tertiary, Cretaceous and Paleozoic age rocks have been interpreted from the Mini-Sosie seismic sections. These structures, although generally not major features themselves, may be associated with deep seated rift-related reactivated structures. Many of the small-offset faults appear to deform or offset Quaternary age sediments. The spatial correlation of the observed faulting with sandblows and lineaments identified from aerial photographs, suggests the possibility that the observed faulting, sandblows, and linear features may be genetically related. If this is the case, then, because the origin of the sandblows has generally been attributed to the 1811–1812 seismic activity, the observed faulting may have been active at that time. It is not possible to directly link a single correlatable seismic signature with the Bootheel lineament, and thus we cannot state unequivocally that the lineament is continuous from Blytheville, Arkansas to New Madrid, Missouri. However, each seismic line has imaged similar small-offset faulting and gentle folding. If the faults and deformation observed are directly caused by reactivated deep structures associated with the Bootheel lineament, then, due to its great length, the total of which is yet undefined, this structure may be a source zone for major earthquakes, and therefore requires further investigations. The possibility exists, however, that the small scale faulting and deformation are ubiquitous throughout the New Madrid seismic zone. Additional high resolution seismic data are required to resolve this question.

Evidence for recurrent faulting in the New Madrid seismic zone from Mini‐Sosie high‐resolution reflection data

Geophysics ◽  
1986 ◽  
Vol 51 (9) ◽  
pp. 1760-1788 ◽  
Author(s):  
John L. Sexton ◽  
Paul B. Jones
Keyword(s):  
High Resolution ◽  
Close Association ◽  
Late Eocene ◽  
Small Displacement ◽  
New Madrid Seismic Zone ◽  
Data Sets ◽  
Reverse Fault ◽  
Seismic Zone ◽  
Reflection Data ◽  
New Madrid

A Mini‐Sosie™ high‐resolution seismic reflection survey was conducted on Reelfoot scarp in the northwestern Tennessee portion of the New Madrid seismic zone. Interpretation of the Mini‐Sosie data revealed the need to reinterpret previously collected reflection data obtained from explosive source and Vibroseis® surveys. Interpretation and integration of the three data sets have resulted in a new model for the subsurface of Reelfoot scarp and provide evidence for recurrent movement along Reelfoot fault, the major reverse fault associated with Reelfoot scarp. Estimated displacements on Reelfoot fault vary from 60 m (60 ms) for late Paleozoic rocks to 15 m (20 ms) for late Eocene sedimentary units. No clear offsets are observed on this particular fault for units younger than late Eocene age; however, uplift, folding, and related structures are observed in younger sediments. An observed variation of offset with depth (age) and the presence of the younger structures are evidence of reactivation of Reelfoot fault. Small‐offset (10 to 20 m) faults were also detected and have been interpreted to have constant displacement with depth, and therefore, to have occurred as a single faulting event rather than as recurrent movement on a fault plane. Two of these faults are interpreted to have been formed in the middle to late Eocene. A small reverse fault located a few hundred feet east of Reelfoot fault appears to be a single faulting event which extends into sediments of Holocene age. There is a small displacement graben structure which probably extends into Holocene age sediments near the apex of the folded sediments of Reelfoot scarp. The location of the graben structure coincides with a zone of small‐offset nomal faulting with 2 to 3 m of total offset within Holocene sediments observed in a trench excavated over Reelfoot scarp. This small zone of faulting has previously been interpreted to be of tectonic origin. The close association of the faults observed in the trench and the graben structure observed on the seismic data suggests that the two features are directly related, and that both structures were formed by Holocene‐era reactivation of Reelfoot fault. Additional evidence supporting our interpretation is provided by synthetic seismograms for models derived from the various data sets and paleosections of the high‐resolution reflection data. A fault map based on all the reflection data shows that our interpretation is consistent with the data sets.

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