INDIANA and TENNESSEE Earthquakes

I have no idea but it is very interesting

This shallow depth of quakes is making me curious. I've noticed the other recent quakes are around 6 to 20 miles deep and some quakes obviously much deeper like a recent one in Spain that was 300 miles deep. So, would something man made cause a quake right on the surface??? or is this not unusual for these type of shallow quakes?

I don't think it's real unusual in this part of america at all,I am more interested in the places these are happening

True. Have seen some quakes in unusual places recently. The smaller UTAH quakes seem to be very shallow as well. Maybe its just a preshock of something big in this southeastern area. Seems overdue for something based on history of the area I have read

This report on the 1811-12 New Madrid earthquake even makes me feel that liquafaction will be a major issue: [link to www.ceri.memphis.edu]

An excerpt from the report:

I happened to be passing in its neighborhood where the principal shock took place... the water that had filled the
lower cavities. . . rushed out in all quarters, bringing with it an enormous quantity of carbonized wood.. . which was
ejected to the height of from ten to fifteen feet, and fell in a black shower, mixed with the sand which its rapid motion
had forced along; at the same time, the roaring and whistling produced by the impetuosity of the air escaping from its
confinement, seemed to increase the horrible disorder of the trees which everywhere encountered each other, being
blown up cracking and splitting, and failing by thousands at a time. In the mean time, the surface was sinking and a
black liquid was rising up to the belly of my horse, who stood motionless, struck with a panic of terror. . . . . These
occurrences occupied nearly two minutes; the trees, shaken in their foundation, kept failing here and there,
and the whole surface of the country remained covered with holes, which... resembled so many craters of
volcanics...

(page 5)

that is very interesting! thanks for that information. will study up more on the new madrid and its past

Thank YOU for opening the conversation! I live in 'no-one-knows-for-sure' land in the foothills of the Smokies (about 30 miles NE of the Tennessee earthquakes, last week), and have become very interested in the long-ago quake that shook church bells in Washington, DC.

Do you think the breadth of the shake (in 1811) is possibly due to it's shallowness in bedrock? I don't think they were able to measure the depth back then.

And, according to the report i'm digesting ( [link to www.ceri.memphis.edu] the New Madrid seismic zone has only recently become a subject of interest. Apparently, the advent of proposed nuclear power plants for that area in the last two decades is what pointed up the need for more understanding of what actually happened a century ago...

This paragraph, excerpted from the summary (page 25) of this report written in 1996, indicates the surface of knowledge has only been scratched:

"We have presented a faulting scenario for the 1811-1812 New Madrid earthquakes that is consistent
with the available historical, geological, and geophysical evidence. This evidence - compiled primarily
within the past two decades- to a large measure confirms the past anecdotal reports of the dramatic effects
of the earthquakes on the land and the river of the central Mississippi Valley. The seismic moment release
of this earthquake series probably equals or exceeds the total of the continental western United States in
historic times. How this can be when the New Madrid seismic zone lies deep within the stable midplate
crust of North America leads us back to Churchill's description of Russia: Despite all the research advances
of the past several decades, much about the 1811-1812 New Madrid earthquakes remains a riddle wrapped
in a
mystery inside an enigma."

If the zone lies so deep, why are the quakes so shallow and far-reaching? Dang it! I wanted to add to the answer and not the question. Thank you, again, OP, for asking the question.

Not sure what fault lies in Tenn...but in Indiana along where this one took place, we are on a northern extention of the New Madrid, called the Wabash Fault. Runs along the Wabash River. I live less than a mile from it.

Oops, that was from me, 12000Eyes. I'm new to GLP and only lurked for a couple of months before giving in to the irresistible urge to join in the conversation. Please bear with me as i learn my way around...

Somewhere i read that there are SO many faults along the base of the Smoky Mountains that many are as of yet unknown, and most are unnamed. I'll see if i can dig up the source to refresh my taxed memory.

There are three types of earthquakes- ones where the plates pull apart, ones where they push against each other, and ones called strike=slip earthquakes where two plates rub together horizontally. Those are the type that are the most shallow, but also cause the most damage because they happen closer to the surface of the ground and sometimes even tear the ground apart. I don't know for sure but it sounds like the New Madrid fault is having shallow quakes for that reason. A low magnitude e.q. can do a lot more damage than a high magnitude one if it is shallow. It sounds scary that the New Madrid quake was shallow because if there was a high magnitude e.q. there again like there was in the early 1800s it could cause extreme damage if it was shallow.