Relations possibles entre la microseismicité récente et l'astroblème de Charlevoix

1983 ◽  
Vol 20 (10) ◽  
pp. 1613-1618 ◽  
Author(s):  
Denis W. Roy ◽  
Reynald DuBerger
Keyword(s):  
Shock Wave ◽  
North America ◽  
Seismic Activity ◽  
Ground Surface ◽  
Vertical Axis ◽  
Normal Faults ◽  
Eastern North America ◽  
Direct Effects ◽  
Mantle Boundary ◽  
Crustal Stresses

The limit of the direct effects of the Charlevoix astrobleme in the upper part of the Earth's crust outlines approximately a revolution paraboloid about a vertical axis. It reaches 14 km in depth below the center of the astrobleme and exhibits a 27 km radius at the present-day ground surface. The microearthquakes, which reflect the regional crustal stresses in eastern North America, occur on the normal faults characteristic of the St. Lawrence Lowland tectonic terrain mainly near the astrobleme paraboloid or near a second paraboloid located 7.9 km outside the first one. This second one could result from some yet undefined interference between the crust–mantle boundary and the shock wave responsible for the formation of the astrobleme 350 Ma ago. The very low seismic activity in the vicinity of Petite-Rivière–Saint-François may imply that energy is now building up in that area.

Synthesis of Recent Paleoseismic Research on Quaternary Faulting in the Eastern Tennessee Seismic Zone, Eastern North America: Implications for Seismic Hazard and Intraplate Seismicity

2022 ◽  
Author(s):  
Randel Tom Cox ◽  
Robert D. Hatcher ◽  
Steven L. Forman ◽  
Ronald Counts ◽  
James Vaughn ◽  
...  
Keyword(s):  
North America ◽  
Seismic Activity ◽  
Plate Boundary ◽  
Thrust Fault ◽  
Normal Faults ◽  
Earthquake Activity ◽  
Intraplate Seismicity ◽  
Seismic Zone ◽  
Basement Fault ◽  
Eastern Tennessee Seismic Zone

ABSTRACT Causes of intraplate seismicity remain a great unsolved problem, in contrast with plate-boundary seismicity. Modern seismicity records frequent seismic activity in plate-boundary seismic zones, but in fault zones where seismic activity is not frequent, plate boundary or intraplate, resolution of prehistoric earthquake activity is critical for estimating earthquake recurrence interval and maximum expected magnitude. Thus, documenting prehistoric earthquakes is crucial for assessing earthquake hazard posed to infrastructure, including nuclear reactors and large dams. The ∼400 km long eastern Tennessee seismic zone (ETSZ), United States, is the third most active seismic zone east of the Rocky Mountains in North America, although the largest recorded ETSZ earthquake is only Mw 4.8. Ironically, it is the least studied major eastern U.S. seismic zone. Recent ETSZ field surveys revealed an 80 km long, 060°-trending corridor containing northeast-striking Quaternary thrust, strike slip, and normal faults with displacements ≥1 m. It partially overlaps a parallel trend of seismicity that extends 30 km farther southwest, suggesting this active faulting zone may extend ∼110 km within part of the ETSZ. Near Dandridge, Tennessee, a thrust fault in French Broad River alluvium records two earthquakes in the last 40,000 yr. About 50 km southwest near Alcoa, Tennessee, a thrust fault cuts Little River alluvium and records two earthquakes between 15,000 and 10,000 yr ago. About 30 km farther southwest at Vonore, Tennessee, a thrust fault displaces bedrock ≥2 m over colluvium, and alluvium is normal faulted >2 m. This corridor, just west of the Blue Ridge escarpment, overlies a steep gradient in midcrustal S-wave velocities, consistent with a basement fault at hypocentral depths. The corridor faults may be connected to a basement fault or localized coseismic faults above a blind basement fault. Our current data suggest at least two Mw≥6.5 surface rupturing events in the last 40,000 yr.

The Identification and Study of Indian Shell Middens in Eastern North America: 1643–1861

1986 ◽  
Vol 6 (3) ◽  
pp. 227-243 ◽  
Author(s):  
Andrew L. Christenson
Keyword(s):  
Nineteenth Century ◽  
Civil War ◽  
North America ◽  
East Coast ◽  
Eastern North America ◽  
Shell Midden ◽  
Shell Middens ◽  
Work Done

Although the interest in shell middens in North America is often traced to reports of the discoveries in Danish kjoekkenmoeddings in the mid-nineteenth century, extensive shell midden studies were already occurring on the East Coast by that time. This article reviews selected examples of this early work done by geologists and naturalists, which served as a foundation for shell midden studies by archaeologists after the Civil War.

HAVE WE SEEN THE LARGEST EARTHQUAKES IN EASTERN NORTH AMERICA?

2018 ◽  
Author(s):  
James S. Neely ◽  
◽  
Seth Stein ◽  
Miguel Merino ◽  
John Adams
Keyword(s):  
North America ◽  
Eastern North America
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