The June 13, 1975 earthquake and its relationship to the New Madrid seismic zone

abstract The June 13, 1975 earthquake in the New Madrid seismic zone produced the first recorded strong-motion accelerograms for an event in the region, as well as the largest recorded accelerations to date for any event in eastern North America. The peak strong-motion values obtained from an analysis of the accelerograms are the following: amax = 43 cm/sec2, vmax = 1 cm/sec and dmax = 0.05 cm for the longitudinal S88°W component; amax = 31 cm/sec2, vmax = 0.6 cm/sec and dmax = 0.01 cm for the DOWN component; amax = 64 cm/sec2, vmax = 1.6 cm/sec2, and dmax = 0.09 cm for the tangential S02°E component. Source parameter estimation using long-period surface waves, Lg spectra, P-wave first motions and the integrated accelerograms leads to a consistent solution. The seismic moment is estimated to be 4E21 dyne-cm and the corner period 0.6 sec. The corner period-seismic moment pair for this event agrees with the regional scaling of these parameters observed by Street et al. (1975).

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Indication of active Faults in the New Madrid Seismic Zone from Precise Location of Hypocenters

Seismological Research Letters ◽

10.1785/gssrl.59.4.123 ◽

1988 ◽

Vol 59 (4) ◽

pp. 123-131 ◽

Cited By ~ 15

Author(s):

L. Himes ◽

W. Stauder ◽

R. B. Herrmann

Keyword(s):

Active Faults ◽

P Wave ◽

New Madrid Seismic Zone ◽

Supporting Evidence ◽

Seismic Zone ◽

Low Velocity ◽

Focal Mechanism Solutions ◽

Velocity Models ◽

Planar Surfaces ◽

New Madrid

Abstract The hypocenter locations of the larger and better recorded earthquakes of the New Madrid seismic zone are examined in order to determine how closely the hypocenters lie along planar surfaces, thus relating the foci to active fault surfaces. For this purpose more than 500 earthquakes of the region have been selected for study, based on the number (7 or more) of observing stations used in the initial hypocenter location and on the quality of the P-wave onset. These events are relocated using a joint hypocenter-velocity-depth (JHVD) algorithm. The relocated earthquakes are separated geographically into three trends: ARK, the southwest trending zone from Caruthersville, Missouri, to Marked Tree, Arkansas; DWM, the northeast trending zone from New Madrid to Charleston, Missouri; and CEN, the central, left-stepping offset zone from Ridgely, Tennessee, to New Madrid, Missouri. Vertical profiles taken along and across the ARK and DWM trends verify the strike and dip of dominantly strike slip motion on near vertical active faults along these trends. These results agree with previously determined composite focal mechanism solutions for these trends. No coherent picture has been obtained for the CEN trend. As a by-product of the study, velocity models from the JHVD inversion are found to be reasonably uniform throughout the New Madrid seismic zone, and to offer supporting evidence for the presence of a shallow low velocity zone in the central portion of the Mississippi embayment.

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Mapping P-wave azimuthal anisotropy of the New Madrid seismic zone

Physics of The Earth and Planetary Interiors ◽

10.1016/j.pepi.2019.106296 ◽

2019 ◽

Vol 295 ◽

pp. 106296 ◽

Cited By ~ 1

Author(s):

Zewei Wang ◽

Dapeng Zhao

Keyword(s):

Azimuthal Anisotropy ◽

P Wave ◽

New Madrid Seismic Zone ◽

Seismic Zone ◽

New Madrid

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Focal mechanism studies in the New Madrid seismic zone

Bulletin of the Seismological Society of America ◽

10.1785/bssa0680041095 ◽

1978 ◽

Vol 68 (4) ◽

pp. 1095-1102 ◽

Cited By ~ 6

Author(s):

Robert B. Herrmann ◽

Jose-Antonio Canas

Keyword(s):

Surface Wave ◽

Focal Mechanism ◽

Focal Mechanisms ◽

New Madrid Seismic Zone ◽

Seismic Zone ◽

Long Period ◽

Composite Focal Mechanism ◽

Surface Wave Data ◽

Array Geometry ◽

New Madrid

abstract A recent study of seismicity in the New Madrid seismic zone by Stauder et al. (1976) has shown the existence of linear micro-earthquake patterns of up to 120 km in length. This study presents the results of composite microearthquake focal mechanism studies along these trends together with focal mechanisms obtained using long-period surface-wave data from larger events. Due to the present microearthquake array geometry, the composite focal mechanism studies do not indicate a complete picture of the nature of the earthquake processes for all the trends. However, the motion on the major 120-km long trend into northeastern Arkansas has significant components of right lateral fault motion. The consistency of surface-wave focal mechanisms and the composite focal mechanism along this trend indicates that it should be considered as a single tectonic unit.

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Noise to signal: A microtremor study at liquefaction sites in the New Madrid Seismic Zone

Geophysics ◽

10.1190/1.3374357 ◽

2010 ◽

Vol 75 (3) ◽

pp. B83-B90 ◽

Cited By ~ 12

Author(s):

Kelli Hardesty ◽

Lorraine W. Wolf ◽

Paul Bodin

Keyword(s):

Strong Motion ◽

Sedimentary Basins ◽

Large Earthquake ◽

Sedimentary Facies ◽

New Madrid Seismic Zone ◽

Seismic Zone ◽

Mississippi Embayment ◽

Ground Failure ◽

Liquefaction Susceptibility ◽

New Madrid

Understanding how sedimentary basins respond to seismic-wave energy generated by large earthquake events is a significant concern for seismic-hazard estimation. This study explores the use of microtremors, or ambient noise, for evaluating strong-motion site effects. The study focuses on the Mississippi Embayment in the New Madrid Seismic Zone, where widespread liquefaction and ground failure occurred during the 1811–1812 earthquake sequence. Spectral analyses of microtremor data at sites representing different environments of deposition (and sedimentary facies), different embayment thicknesses, and varying liquefaction susceptibility show correlations between (1) calculated vulnerability indices and evidence of liquefaction, (2) sediment thickness and fundamental resonant frequency, and (3) subsurface stratigraphic boundaries and observed peaks in horizontal-to-vertical spectral ratios. Results of the study suggest that the microtremor method could be helpful in identifying those areas most vulnerable to ground amplification in intraplate sedimentary basins, where large earthquakes are infrequent but potentially damaging.

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