Paleomagnetic evidence of 1811--1812 liquefaction along the Reelfoot scarp, New Madrid seismic zone, Tennessee

Conference · Wed Jan 01 04:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5806888

Salyards, S L ^[1]

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1. Univ. of California, Los Angeles, CA (United States). Southern California Earthquake Center

A trench excavated across the Reelfoot scarp revealed liquefaction features probably of seismic origin. Two prominent liquefaction bodies show diapiric structure but no sign of eruption onto the ground surface and no definitive stratigraphic control on age. Based upon the historic seismic record and the available stratigraphic relationships they interpreted these bodies as having been produced in the 1811--1812 New Madrid earthquakes. A paleomagnetic test of he age of these features was conducted to see if the magnetic directions agreed with the magnetic direction measured in St. Louis in 1819, supporting their origin in 1811--1812. Both features have magnetic directions consistent with this direction, but one of the sandbodies has a much better quality magnetic direction for 6 stable samples of 8 samples total. Rock-magnetic measurements indicate the magnetic remanence is carried by single-domain magnetite suggesting the mean magnetic direction is not a viscous remanent magnetic moment of the present field direction. That the mean direction is due to the present magnetic field is not considered likely but can not be ruled out. The magnetic susceptibility, NRM intensity, and saturation IRM all increase downward in the sandbody showing an increasing magnetite content. The reason for susceptibility increases is not yet determined but preferred explanations are (1) downward settling of magnetite during diapiric emplacement or (2) entrainment of increasing amounts of magnetite with transport of the liquefied sand. These results suggest that the sampled sandbodies were produced in the historic 1811--1812 earthquakes and that paleomagnetics provides a correlation tool useful in paleoseismological studies of prehistoric earthquakes.

• OSTI ID: 5806888
• Report Number(s): CONF-921058--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 24:7
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
DEVELOPED COUNTRIES
EARTHQUAKES
GEOLOGIC FORMATIONS
GEOLOGIC STRUCTURES
GEOLOGY
HISTORICAL ASPECTS
IRON ORES
MAGNETIC PROPERTIES
MAGNETIC SUSCEPTIBILITY
MAGNETISM
MAGNETITE
MINERALS
NORTH AMERICA
ORES
OXIDE MINERALS
PALEOMAGNETISM
PHYSICAL PROPERTIES
SEISMIC EVENTS
SEISMICITY
STRATIGRAPHY
TENNESSEE
USA