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Geology/eqs around Charleston SC

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Question
Hi to all,

USGS and NASA papers and maps show gravity and magnetic anomalies around Charleston SC. Between 2012 and 2015 49 eqs occur, the epicenters (hypocenters) were recorded between -100m and - 18km.
What may causes these eqs ? No tectonic boundary far and wide, -18 km are much too deep for a collapsing sinkhole.

Could the eqs be a long-time-effect of an impact? Collapsing cavities from vaporization of the impactor may cause smaller eqs (max 4.7 in -18km). An impact may explain gravity and magnetic anomalies.

But i have no idea how deep an impactor may penetrate the ground. Of course it depends from speed, diameter, weight, angle and ground structure (sediments, limestone, basalt ...)  Are ground section maps of SC available? I can't find some.

I also think that this impactor (if existing) could not have caused the Carolina Bays in the same event. The impactor get into in an almost right angle, the CBs were formed by a shower from NW to SE incoming with may be 45 .

Finally my concern: Are there researches made to explain the Charleston earthquakes and are there explanations for the widespread hypocenters?

I appreciate your help!

Connie

Answer
Connie

I am wondering, is this some sort of homework or school work question?  If not, what is driving this interest?

Do you have a map of the occurrence of these earthquakes? I would be curious to know if they are aligned at all or if the epicenters are random in distribution.

My initial hunch is that this could be related to some loading or unloading of hte continental shelf and perhaps even some isostatic rebound.

Does this help?

Regards

Geology

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Fraser Hamilton

Expertise

I have over 15 years of professional experience in the environmental geology field. I am well versed in general geology types of questions and answers. In addition I have a keen understanding of physical stratigraphy (especially in the Valley and Ridge of Central PA) and cycles.

Experience

Eight years of education, fifteen years of professional experience. Have worked or studied in ME, PA, TX, KY, IN, TN, OH, WA and Scotland.

Publications
Geological Society of America
American Association of Petroleum Geologists
Properties Magazine
Cleveland Bar Association
Cleveland Engineering Society

Education/Credentials
BA Geology/Math, University of Maine at Farmington
MA Geology - Physical Stratigraphy, Temple University
Post Grad Studies Geology - Texas A&M University

Awards and Honors
Distinguished graduate teaching award, Temple University

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