Mini-sosie high-resolution reflection survey of the Cottonwood Grove fault in northwestern Tennessee

1988 ◽  
Vol 78 (2) ◽  
pp. 838-854
Author(s):  
John L. Sexton ◽  
Paul B. Jones
Keyword(s):  
High Resolution ◽  
Middle Eocene ◽  
Strike Slip ◽  
New Madrid Seismic Zone ◽  
Reverse Fault ◽  
Seismic Zone ◽  
Registered Trademark ◽  
The North ◽  
Paleozoic Rocks ◽  
New Madrid

Abstract The Cottonwood Grove fault is located within a portion of the New Madrid seismic zone in northwestern Tennessee. Focal mechanism studies indicate that this area is a seismic transition zone. To the southwest is a southwest-northeast seismic trend in which movements along deeper seated faults is predominantly right-lateral strike-slip. To the north is a southeast-northwest seismic trend in which reverse and normal faulting predominate. The Cottonwood Grove fault is buried beneath the poorly consolidated sediments of the Mississippi embayment. The fault, as identified by an earlier Vibroseis ®* survey is a northeast-southwest trending, eastward-dipping reverse fault with approximately 75 m (245 ft) of displacement on the Paleozoc-Cretaceous boundary. A Mini-Sosie™† high-resolution seismic reflection survey was conducted through the village of Cottonwood Grove along the previously surveyed Vibroseis line to improve estimates of the age, geometry, and displacements of the Cottonwood Grove fault. Results of the Mini-Sosie survey reveal that displacements across the major fault are relatively consistent within Cretaceous, Paleocene, and middle Eocene sedimentary rocks. In upper Eocene and younger rocks, however, there is no evidence for faulting. Our interpretation includes a previously undetected secondary fault at the boundary between upper Cretaceous and Paleocene rocks. Also included in our interpretation of the subsurface profile through Cottonwood Grove is an Eocene age channel feature located 2 km east of the Cottonwood Grove fault. In addition, the Paleozoic-Cretaceous boundary is interpreted to be an erosional surface with no intrusives included in the Paleozoic rocks. Synthetic seismogram modeling, detailed gravity survey data, and theoretical gravity calculations support this interpretation, and indicate that shallow intrusive bodies within Paleozoic rocks are not needed to explain the observed data. Seismic reflections which would be expected if the intrusives were present are not observed, and the observed Bouguer gravity anomaly can be explained by use of irregularities on the erosional Paleozoic bedrock surface along with sedimentary features within the post-Paleozoic sediments. These data suggest that Cottonwood Grove fault formed during middle Eocene time and that since that time, any major movement on deeper faults has been predominantly strike-slip with little or no vertical reactivation. This interpretation is consistent with the prevailing hypotheses relating current seismicity of the New Madrid seismic zone to the contemporary regional compressive stress field acting on zones of weakness associated with the Precambrian Reelfoot Rift Complex. ®* Registered trademark of Conoco, Inc. ™† Registered trademark of Société Nationale Elf Aquitane (Production).

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.

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

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

Faulting along the southern margin of Reelfoot Lake, Tennessee

1998 ◽  
Vol 88 (1) ◽  
pp. 131-139 ◽  
Author(s):  
Roy Van Arsdale ◽  
Jodi Purser ◽  
William Stephenson ◽  
Jack Odum
Keyword(s):  
Fault Zone ◽  
Lake Basin ◽  
New Madrid Seismic Zone ◽  
Reverse Fault ◽  
Seismic Reflection Profile ◽  
Seismic Zone ◽  
Seismic Line ◽  
Southern Margin ◽  
Main Shocks ◽  
New Madrid

Abstract The Reelfoot Lake basin, Tennessee, is structurally complex and of great interest seismologically because it is located at the junction of two seismicity trends of the New Madrid seismic zone. To better understand the structure at this location, a 7.5-km-long seismic reflection profile was acquired on roads along the southern margin of Reelfoot Lake. The seismic line reveals a westerly dipping basin bounded on the west by the Reelfoot reverse fault zone, the Ridgely right-lateral transpressive fault zone on the east, and the Cottonwood Grove right-lateral strike-slip fault in the middle of the basin. The displacement history of the Reelfoot fault zone appears to be the same as the Ridgely fault zone, thus suggesting that movement on these fault zones has been synchronous, perhaps since the Cretaceous. Since the Reelfoot and Ridgely fault systems are believed responsible for two of the main-shocks of 1811-1812, the fault history revealed in the Reelfoot Lake profile suggests that multiple mainshocks may be typical of the New Madrid seismic zone. The Ridgely fault zone consists of two northeast-striking faults that lie at the base of and within the Mississippi Valley bluff line. This fault zone has 15 m of post-Eocene, up-to-the-east displacement and appears to locally control the eastern limit of Mississippi River migration. The Cottonwood Grove fault zone passes through the center of the seismic line and has approximately 5 m of up-to-the-east displacement. Correlation of the Cottonwood Grove fault with a possible fault scarp on the floor of Reelfoot Lake and the New Markham fault north of the lake suggests the Cottonwood Grove fault may change to a northerly strike at Reelfoot Lake, thereby linking the northeast-trending zones of seismicity in the New Madrid seismic zone.

Structure of the Blytheville Arch in the New Madrid Seismic Zone

1988 ◽  
Vol 59 (4) ◽  
pp. 117-121 ◽  
Author(s):  
R.M. Hamilton ◽  
F.A. McKeown
Keyword(s):  
Seismic Hazard Assessment ◽  
New Madrid Seismic Zone ◽  
Seismic Zone ◽  
Middle Cambrian ◽  
Seismic Reflection Profiles ◽  
Paleozoic Rocks ◽  
Drill Holes ◽  
The Relationship ◽  
Strike Slip Movement ◽  
New Madrid

Abstract Seismic-reflection profiles across part of the New Madrid seismic zone in northeastern Arkansas and southeastern Missouri show a faulted and structurally complex zone, originally known as Charlie’s ridge but herein renamed Blytheville arch, which is about 10 to 15 km wide and about 110 km long. Several exploratory drill holes in the arch penetrate Upper and possibly Middle Cambrian formations directly below Cretaceous rocks, whereas drill holes off the arch penetrate the Cambrian and Ordovician Knox and Arbuckle Groups equivalents and possibly younger Paleozoic rocks below the Cretaceous; therefore, the pre-Cretaceous rocks in the arch are structurally high. Most earthquakes in the northeast-trending segment of the New Madrid seismic zone along the axis of the Reelfoot rift occur along the arch. Focal mechanisms of earthquakes in the trend show right-lateral, strike-slip movement. Epicenters in the northeastern part of the seismic trend between Caruthersville, MO, and Blytheville, AR, are spatially less dispersed than those to the southwest between Blytheville and Marked Tree, AR. Most of the hypocenters to the northeast cluster between 6 to 12 km deep, whereas those to the southwest range from near the surface to about 15 km deep. Earthquakes in the northeast part of the seismic trend are concentrated along a fault zone under the arch, whereas those to the southwest are more dispersed under the arch. A seismic trend that extends south-southwest from near Charleston, MO, projects to the northwest side of the ridge near Blytheville, where the seismicity changes character and the southeast boundary of the arch trends more easterly. The relationship between the structural boundaries of the arch and the seismicity may establish the extent of part of New Madrid seismicity and improve the basis for seismic hazard assessment.

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.

How Old is the New Madrid Seismic Zone?

1994 ◽  
Vol 65 (2) ◽  
pp. 172-179 ◽  
Author(s):  
Thomas L. Pratt
Keyword(s):  
Fault Zone ◽  
Fault Model ◽  
New Madrid Seismic Zone ◽  
Reverse Fault ◽  
Seismic Zone ◽  
Lake County ◽  
Recurrence Times ◽  
Analysis Techniques ◽  
Large Earthquakes ◽  
New Madrid

Abstract Current seismicity levels on the New Madrid seismic zone should produce about 0.11 cm/year of horizontal slip which, when compared with uplift of 42 m in the subsurface strata below the Lake County uplift and assuming a 31° reverse fault model, indicates that the present seismicity levels could not have been present for more than about 64,000 years. If seismicity in the region has persisted for a much longer period of time, then (1) the seismicity has moved spatially between several deformed zones (Crowley’s Ridge and the Crittenden County fault zone); (2) the seismicity is episodic in nature, and active periods similar to the present occur between long quiescent times; or (3) there have been far fewer large earthquakes than predicted by extrapolation of the Gutenberg-Richter relation to higher magnitudes. Any of these scenarios indicates that assessing the hazard from large earthquakes is more complicated than conventional analyses have assumed because either the seismicity locations or rates change or analysis techniques relying on the Gutenberg-Richter relation are invalid for estimating the recurrence times of large earthquakes in the New Madrid area.

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