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Quake Watch 2010

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posted on Feb, 28 2010 @ 05:48 AM
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CNN are reporting the latest 6.2 Maule, Chile quake as a new event and that it's not an aftershock.




posted on Feb, 28 2010 @ 05:51 AM
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Two new eartquakes in few minutes over 6 in chile...

28.02.2010 - 11:25:37 6.1 South America Chile Region Santa Cruz
28.02.2010 - 11:25:35 6.1 South America Chile Region del Maule



posted on Feb, 28 2010 @ 05:57 AM
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reply to post by PuterMan
 

Thank you for the clarification. Yes, they do apparently classify the Northern Mid-Atlantic Ridge as anything north of the equator. It's then up to the researcher to identify the location more specifically by the coordinates, and then go from there to check regional historic seismicity and quake density. This is why I don't just go by naming of locations to check such data, but prefer instead to search by lat. and long. within a target area.

In the case I was discussing on the Chile thread, that specific area where the 5.4 occurred yesterday is, in fact, one of its quieter zones and hasn't moved much in the past year or two. That's why I suggested it could have been affected by remote triggering from the Chile quake, as it had a 5-plus on the same day.

As you can imagine it freaked me out pretty badly when you cited such radically different data!
But now I follow your own data referencing, all is cool.

From my own observations over the past few years it seems that the upper latitudes of the Northern Mid-Atlantic Ridge tend to be more active than this one nearer the equator. I have no idea why that is, though. But that ridge and especially it's more northern reaches could be quite significant in terms of seismic activity in other places, which one reason I keep an eye on it. (If you'd like to know more just PM me and I'll refer you to some other posts I have on site about this.)

Mike



posted on Feb, 28 2010 @ 06:02 AM
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reply to post by JanusFIN
 

Could you please provide a link/links to your sources that show two different mag 6-plus quakes? According to this USGS data page there was a mag 6.2 in Chile at 11:25:35 UTC today, but I cannot find any data for another one in Chile near the same time frame.

Thank you.

Mike

EDIT: the above-referenced mag 6.2 now downgraded to a mag 6.1. Still nothing on USGS to indicate another 6.1 in the same region/time frame. The EMSC latest quakes page also only shows one 6.1 quake.


[edit on 28/2/10 by JustMike]



posted on Feb, 28 2010 @ 06:10 AM
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reply to post by JustMike
 


As they would say at UEA, what's a few data differences between friends?

Yes will do as this area, the cracks in the skin that run down the middle, are of interest to me.



posted on Feb, 28 2010 @ 06:23 AM
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Noob here, been cruising ATS for a while now and thought it was time to join.
Great site for global disaster info including quakes.

Two new ones in Chile.

hisz.rsoe.hu...

BBx2.



posted on Feb, 28 2010 @ 06:27 AM
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reply to post by JustMike
 


sorry delay... here is information from link:
hisz.rsoe.hu...



posted on Feb, 28 2010 @ 06:33 AM
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Magnitudes in Chile with power trend line since this started - excluding the 5.0 that just popped off.



Found some sort of Chilean seismo service

I just add this as a matter of interest.

[edit on 28/2/2010 by PuterMan]



posted on Feb, 28 2010 @ 04:38 PM
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5.1 Honshu right in a built up area.

Magnitude 5.1
Date-Time

* Sunday, February 28, 2010 at 22:07:47 UTC
* Monday, March 01, 2010 at 07:07:47 AM at epicenter
* Time of Earthquake in other Time Zones

Location 39.508°N, 140.426°E
Depth 124.4 km (77.3 miles)
Region EASTERN HONSHU, JAPAN
Distances 40 km (25 miles) SE of Akita, Honshu, Japan
65 km (40 miles) WSW of Morioka, Honshu, Japan
145 km (90 miles) SW of Hachinohe, Honshu, Japan
430 km (265 miles) N of TOKYO, Japan
Location Uncertainty horizontal +/- 8.5 km (5.3 miles); depth +/- 2.5 km (1.6 miles)
Parameters NST=203, Nph=236, Dmin=361.8 km, Rmss=0.63 sec, Gp=112°,
M-type=body wave magnitude (Mb), Version=6
Source

* USGS NEIC (WDCS-D)

Event ID us2010tgd8

Kamioka appears to be the largest settlement nearby. (approx 1 mile)

Quite deep though so maybe not a problem.

[edit on 28/2/2010 by PuterMan]



posted on Mar, 1 2010 @ 06:23 AM
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reply to post by JanusFIN
 

Hello Janus,

sorry for my own delay in getting back to your response. Thanks for the info. RSOE is a good resource for first reporting as they sometimes get things onto the map before others.

With the two quakes they initially reported, what most likely happened is that they got the first, auto-generated report of a mag 6.1 quake and so it was automatically added to the map by their own program. However, it's quite common that early reports get revised with slight variations to event time, location and (possibly) magnitude. This is because as more data comes in from other stations they can refine the initial estimates. So, a new report got released, and as it was slightly different from the first it auto-displayed on RSOE as a separate event.

They've since revised the map to show only the one event.

RSOE is particularly susceptible to this problem of duplicate reporting because it's like a "clearing house" for all sorts of hazard reports, and not just quakes. That's why it's good to cross-check with other, dedicated quake sites like USGS, EMSC and geonet.

Best regards,

Mike



posted on Mar, 1 2010 @ 06:32 AM
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reply to post by PuterMan
 

Yes, that's a pretty deep quake and for the Japanese, not such a big one. With their building codes most structures would be virtually unaffected. It's when they get above a mag 6 that things start getting worrisome, especially if the event is relatively shallow.

Also:
reply to post by PuterMan
 

Thank you very much for that graph.
(Star 4 u.) It helps to illustrate the typical trend following a huge quake like this one. It's perfectly natural for there to be a large number of aftershocks, especially when subduction is involved and a big chunk of (undersea) real estate has to finish settling into its new position. We could see significant aftershocks for several more days at least.

Let's just hope the big shift that happened there doesn't get another section of the Nazca plate on the move in a similar way.
Best regards,

Mike



posted on Mar, 1 2010 @ 01:27 PM
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I think I answered my own question...

[edit on 1-3-2010 by Casing]



posted on Mar, 1 2010 @ 05:07 PM
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Is it normal to have all these quakes in the same area, look at all the Chile Quakes since the 27th

01-MAR-2010 17:23:32 -34.80 -73.92 5.0 19.2 OFF COAST OF CENTRAL CHILE
01-MAR-2010 16:56:49 -36.31 -72.48 5.2 35.0 NEAR COAST OF CENTRAL CHILE
01-MAR-2010 15:52:38 -36.77 -73.61 4.9 35.0 NEAR COAST OF CENTRAL CHILE
01-MAR-2010 14:36:29 -34.36 -73.43 5.3 30.1 OFF COAST OF CENTRAL CHILE
01-MAR-2010 13:09:29 -36.56 -73.43 4.5 35.0 NEAR COAST OF CENTRAL CHILE
01-MAR-2010 12:48:22 -38.38 -73.87 4.8 35.0 NEAR COAST OF CENTRAL CHILE
01-MAR-2010 12:27:15 -34.22 -71.82 5.3 35.0 NEAR COAST OF CENTRAL CHILE
01-MAR-2010 12:20:18 -34.51 -73.64 5.2 35.0 OFF COAST OF CENTRAL CHILE
01-MAR-2010 10:17:29 -36.39 -71.86 4.8 35.0 CENTRAL CHILE
01-MAR-2010 09:23:00 -35.62 -71.76 4.8 35.0 CENTRAL CHILE
01-MAR-2010 08:58:33 -37.70 -74.39 5.3 35.0 OFF COAST OF CENTRAL CHILE
01-MAR-2010 08:46:59 -35.40 -71.03 4.9 35.0 CENTRAL CHILE
01-MAR-2010 07:49:07 -35.00 -72.86 5.3 35.0 NEAR COAST OF CENTRAL CHILE
01-MAR-2010 07:39:17 -35.97 -72.70 4.9 35.0 NEAR COAST OF CENTRAL CHILE
01-MAR-2010 07:29:15 -33.83 -72.25 4.7 35.0 OFF COAST OF CENTRAL CHILE
01-MAR-2010 06:24:52 -33.93 -73.09 4.8 35.0 OFF COAST OF CENTRAL CHILE
01-MAR-2010 06:16:11 -37.58 -74.53 5.1 35.0 OFF COAST OF CENTRAL CHILE
01-MAR-2010 05:36:57 -36.80 -73.52 4.9 35.0 NEAR COAST OF CENTRAL CHILE
01-MAR-2010 05:30:36 -34.45 -73.48 5.2 35.0 OFF COAST OF CENTRAL CHILE
01-MAR-2010 03:53:16 -38.64 -73.12 5.0 35.0 NEAR COAST OF CENTRAL CHILE
01-MAR-2010 03:07:50 -36.12 -72.80 5.1 40.0 NEAR COAST OF CENTRAL CHILE
01-MAR-2010 02:44:42 -35.09 -72.61 5.8 26.0 NEAR COAST OF CENTRAL CHILE
01-MAR-2010 01:10:58 -35.16 -71.70 5.4 42.6 CENTRAL CHILE
01-MAR-2010 00:49:15 -34.66 -72.56 4.8 35.3 NEAR COAST OF CENTRAL CHILE
01-MAR-2010 00:01:27 -38.31 -73.75 5.0 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 23:49:05 -37.36 -72.95 5.1 35.0 CENTRAL CHILE
28-FEB-2010 23:45:06 -35.28 -72.26 5.0 34.9 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 22:41:29 -36.84 -73.53 5.0 26.5 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 22:03:05 -34.20 -72.01 4.9 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 19:48:38 -38.06 -73.53 5.8 29.4 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 19:10:06 -36.83 -73.49 4.9 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 19:01:08 -36.49 -73.51 4.8 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 18:44:30 -36.63 -72.51 5.1 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 18:25:15 -35.82 -73.39 4.9 36.4 OFF COAST OF CENTRAL CHILE
28-FEB-2010 18:19:53 -34.85 -71.61 5.0 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 18:14:12 -34.37 -73.58 4.8 35.0 OFF COAST OF CENTRAL CHILE
28-FEB-2010 16:03:39 -37.48 -73.41 4.8 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 15:46:24 -35.33 -72.17 5.2 28.7 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 15:26:54 -35.08 -72.06 5.0 29.8 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 14:55:24 -33.88 -73.29 5.1 32.7 OFF COAST OF CENTRAL CHILE
28-FEB-2010 14:50:32 -33.82 -73.16 5.2 23.6 OFF COAST OF CENTRAL CHILE
28-FEB-2010 14:30:50 -36.03 -73.41 4.7 29.3 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 13:47:06 -35.33 -72.92 5.0 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 12:34:29 -36.01 -72.35 4.8 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 12:18:59 -38.13 -73.34 5.2 26.5 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 12:01:15 -35.81 -72.79 5.0 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 11:50:36 -35.07 -72.73 5.2 20.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 11:25:35 -34.74 -70.87 6.1 35.0 CHILE-ARGENTINA BORDER REGION
28-FEB-2010 11:14:26 -35.32 -72.66 5.0 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 10:43:11 -38.41 -75.22 5.1 35.0 OFF COAST OF CENTRAL CHILE
28-FEB-2010 10:11:07 -33.91 -72.03 5.0 35.0 OFF COAST OF CENTRAL CHILE
28-FEB-2010 09:14:53 -33.59 -71.77 5.2 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 09:01:23 -38.48 -73.33 4.9 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 08:47:19 -34.60 -73.73 4.7 35.0 OFF COAST OF CENTRAL CHILE
28-FEB-2010 08:15:06 -33.58 -68.36 4.9 24.7 MENDOZA PROVINCE, ARGENTINA
28-FEB-2010 08:07:46 -35.18 -72.52 5.0 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 07:36:30 -37.76 -73.14 5.0 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 07:14:20 -38.35 -73.51 5.1 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 06:22:57 -38.00 -73.05 4.9 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 05:19:35 -37.70 -73.41 5.3 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 05:13:59 -37.46 -73.01 5.3 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 05:04:05 -35.23 -71.21 5.0 35.0 CENTRAL CHILE
28-FEB-2010 04:55:49 -33.93 -71.94 5.3 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 04:29:12 -34.90 -69.63 5.0 35.0 CHILE-ARGENTINA BORDER REGION
28-FEB-2010 04:17:52 -34.72 -72.18 5.0 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 04:12:52 -34.83 -72.95 4.6 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 04:04:51 -33.74 -73.09 4.9 35.0 OFF COAST OF CENTRAL CHILE
28-FEB-2010 03:23:49 -37.68 -73.53 5.2 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 03:20:15 -33.06 -74.05 4.8 35.0 OFF COAST OF CENTRAL CHILE
28-FEB-2010 03:14:11 -33.96 -73.19 5.1 35.0 OFF COAST OF CENTRAL CHILE
28-FEB-2010 03:13:39 -35.21 -72.75 4.9 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 02:41:09 -38.05 -73.21 5.1 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 02:38:31 -38.27 -73.63 5.4 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 02:13:14 -33.00 -72.80 4.8 35.0 OFF COAST OF CENTRAL CHILE
28-FEB-2010 02:04:29 -34.61 -73.53 5.0 35.0 OFF COAST OF CENTRAL CHILE
28-FEB-2010 01:58:50 -34.88 -72.65 5.2 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 01:45:29 -34.44 -73.73 5.2 35.0 OFF COAST OF CENTRAL CHILE
28-FEB-2010 01:33:12 -36.60 -72.77 5.3 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 01:24:42 -34.73 -73.40 4.8 35.0 OFF COAST OF CENTRAL CHILE
28-FEB-2010 01:08:24 -34.11 -71.95 5.5 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 01:01:12 -36.79 -73.35 5.3 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 00:53:33 -37.95 -73.66 5.1 35.0 NEAR COAST OF CENTRAL CHILE
28-FEB-2010 00:00:49 -36.57 -73.28 5.3 35.0 NEAR COAST OF CENTRAL CHILE
27-FEB-2010 23:35:14 -33.87 -72.23 5.2 34.8 OFF COAST OF CENTRAL CHILE
27-FEB-2010 23:12:35 -34.7

[edit on 1-3-2010 by NotAgain]



posted on Mar, 1 2010 @ 05:35 PM
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reply to post by PuterMan
 


Good find: GUC(Geofisica Universidad de Chile): Sigla con la cual es conocido el Servicio Sismológico de la Universidad de Chile en la Red Sismológica Mundial
It means that is part of the world seismological net at the Geophysical University of Chile. They should have good info.
If you click on "INFORME" you get a map with the location.

[edit on 3/1/2010 by zachi]



posted on Mar, 1 2010 @ 09:23 PM
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Just had a 6.0, revised to 5.8 Luyzon Philipines.

earthquake.usgs.gov...



posted on Mar, 2 2010 @ 05:44 AM
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Originally posted by zachi
reply to post by PuterMan
 


Good find: GUC(Geofisica Universidad de Chile): Sigla con la cual es conocido el Servicio Sismológico de la Universidad de Chile en la Red Sismológica Mundial
It means that is part of the world seismological net at the Geophysical University of Chile. They should have good info.
If you click on "INFORME" you get a map with the location.

[edit on 3/1/2010 by zachi]


Just as a matter of interest. I had a look at the big quake in Chile, which is on that list as an 8.3

As you know we are calling it an 8.8 on the MM scale. Clicking on INFORME and then on Magnitud: I guess it is saying that the quake was an 8.3 on the Richter scale.

The 1960 quake was an 8.8 on the Richter scale which translated to 9.5 on the MM scale. This latest one shows again the differences between the two scales.

Edit:

Looking into this a bit more I note the quake has Mw in another column and in the INFORME info which according to the info on magnitude that they give means that they are recording this as an 8.3 on the MM scale as against the 8.8 that we have it registered as. Anyone care to comment as to whether my assessment is correct?

[edit on 2/3/2010 by PuterMan]



posted on Mar, 2 2010 @ 07:13 AM
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reply to post by NotAgain
 


After a big one like the 8.8 then yes it is perfectly normal to see so many 'aftershocks' and some new quakes as the grounds settles post the release of tension.

I will post another graph in a while

Edit: It is now officially a while! Note that the power trend line is now below the 5.0 whereas in the previous one it was above the 5.0



[edit on 2/3/2010 by PuterMan]



posted on Mar, 2 2010 @ 01:06 PM
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reply to post by PuterMan
 


Hi PuterMan,

I made it over here to Quake Watch 2010 as you wished and will be ready to answer questions later pertaining to earthquakes.

You seem to be very interested in earthquakes. I'm sure my videos at YouTube will really open your eyes as to how science is really used to predict earthquakes 100% accurately anywhere in the world.

www.youtube.com...

This revolutionary technology lets major earthquakes as well as minor earthquakes become detectable 24 hours a day, for day and weeks before the earthquakes can strike.

When the Earth's subsurface becomes stessed the rock throws out radiation that penetrates through rock, water, hills, mountains, buildings and metal. Nothing stops these signals except distance. The further the distance that they are detectable from with the power recieved at that distance is easily computed into magnitude. The greatest signal power means you are over the epicenter; the hypocenter/foci/focal point is directly below and depth is known by the distance to the nodal ring.

It's easy to understand and even children can understand it fully and make correct earthquake forecasts anywhere in the world using the technology in the videos.

www.youtube.com...

Let me know if you don't understand any of the science in the videos and I will explain it to you further, I intend to make more videos when the weather warms up.



posted on Mar, 2 2010 @ 02:19 PM
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Somebody woke up New Madrid it looks like!!!




Magnitude 3.7 - SOUTHEASTERN MISSOURI
2010 March 02 19:37:35 UTC
DetailsMapsEarthquake Details
Magnitude 3.7
Date-Time Tuesday, March 02, 2010 at 19:37:35 UTC
Tuesday, March 02, 2010 at 01:37:35 PM at epicenter

Location 36.787°N, 89.348°W
Depth 5.8 km (3.6 miles)
Region SOUTHEASTERN MISSOURI
Distances 3 km (2 miles) ENE (76°) from East Prairie, MO
5 km (3 miles) SSW (205°) from Anniston, MO
9 km (6 miles) NW (306°) from Pinhook, MO
24 km (15 miles) ESE (116°) from Sikeston, MO
179 km (111 miles) W (279°) from Clarksville, TN
219 km (136 miles) SSE (159°) from St. Louis, MO

Location Uncertainty horizontal +/- 0.5 km (0.3 miles); depth +/- 0.5 km (0.3 miles)
Parameters NST= 25, Nph= 27, Dmin=7 km, Rmss=0.12 sec, Gp=112°,
M-type="Nuttli" surface wave magnitude (mbLg), Version=B
Source Cooperative New Madrid Seismic Network

Event ID nm1937



posted on Mar, 2 2010 @ 02:28 PM
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Been about 100 years or so....hmmmmm

New Madrid Earthquakes 1811-1812


New Madrid 1811-1812 Earthquakes


•Earthquake Summary •Images
•Damage Photos from the USGS Photographic Library
•Isoseismal Map
•Overview
•Eyewithness Accounts

•New Madrid Seismic Zone Links

Earthquake Summary



1811, December 16, 08:15 UTC. Northeast Arkansas
Magnitude ~7.2 - 8.1

On the basis of the large area of damage (600,000 square kilometers), the widespread area of perceptibility (5,000,000 square kilometers), and the complex physiographic changes that occurred, the Mississippi River valley earthquakes of 1811-1812 rank as some of the largest in the United States since its settlement by Europeans. The area of strong shaking associated with these shocks is two to three times larger than that of the 1964 Alaska earthquake and 10 times larger than that of the 1906 San Francisco earthquake.

The magnitude of these series of earthquakes, usually named the New Madrid, Missouri, earthquakes, vary considerably between the mb and Ms values estimated by Nuttli. The mb was estimated from isoseismal maps, and the MS was estimated from a spectral scaling relation by Nuttli for mid-plate earthquakes. The value of MS magnitude has a functional relationship to the mb. The authors have chosen to include the Mfa magnitude because it was estimated from isoseismal maps, as were most of the historical earthquakes.

The first and second earthquakes occurred in Arkansas (December 16, 1811 - two shocks - Mfa 7.2, MSn 8.5 and Mfa 7.0, MSn 8.0) and the third and fourth in Missouri (January 23, 1812, Mfa 7.1, MSn 8.4; and February 7, 1812, Mfa 7.4, MSn 8.8). Otto Nuttli, however, has postulated another strong earthquake in Arkansas on December 16 at 18:00 UTC (MSn 8.0). This would make a total of five earthquakes of magnitude MSn 8.0 or higher occurring in the period December 16, 1811 through February 7, 1812.

The first earthquake caused only slight damage to man-made structures, mainly because of the sparse population in the epicentral area. The extent of the area that experienced damaging earth motion (MM intensity greater than or equal to VII) is estimated to be 600,000 square kilometers. However, shaking strong enough to alarm the general population (MM intensity greater than or equal to V) occurred over an area of 2.5 million square kilometers.

At the onset of the earthquake the ground rose and fell - bending the trees until their branches intertwined and opening deep cracks in the ground. Landslides swept down the steeper bluffs and hillslides; large areas of land were uplifted; and still larger areas sank and were covered with water that emerged through fissures or craterlets. Huge waves on the Mississippi River overwhelmed many boats and washed others high on the shore. High banks caved and collapsed into the river; sand bars and points of islands gave way; whole islands disappeared. Surface rupturing did not occur, however. The region most seriously affected was characterized by raised or sunken lands, fissures, sinks, sand blows, and large landslides that covered an area of 78,000 - 129,000 square kilometers, extending from Cairo, Illinois, to Memphis, Tennessee, and from Crowleys Ridge to Chickasaw Bluffs, Tennessee.

Although the motion during the first shock was violent at New Madrid, Missouri, it was not as heavy and destructive as that caused by two aftershocks about 6 hours later. Only one life was lost in falling buildings at New Madrid, but chimneys were toppled and log cabins were thrown down as far distant as Cincinnati, Ohio; St. Louis, Missouri; and in many places in Kentucky, Missouri, and Tennessee.

The Lake County uplift, about 50 kilometers long and 23 kilometers wide, upwarps the Mississippi River valley as much as 10 meters in parts of southwest Kentucky, southeast Missouri, and northwest Tennessee. The uplift apparently resulted from vertical movement along several, ancient, subsurface structures; most of this uplift has occurred during earthquakes. The Lake County uplift can be subdivided into several topographic bulges, including Tiptonville dome, Ridgely Ridge, and the south end of Sikeston Ridge. A strong correlation exists between modern seismicity and the uplift, indicating that stresses that produced the uplift still exist today.

Tiptonville dome, which is 14 kilometers in width and about 11 kilometers in length, shows the largest upwarping and the highest topographic relief on the uplift. It is bounded on the east by Reelfoot scarp, which has a zone of normal faults (displacement about 3 meters) at its base. Although most of Tiptonville dome formed between 200 and 2,000 years ago, additional uplifting deformed the northwest and southeast parts of the dome during the earthquakes of 1811-1812.

A notable area of subsidence is Reelfoot Lake in Tennessee, just east of Tiptonville dome. Subsidence there ranged from 1.5 to 6 meters, although larger amounts were reported. It may be that the lake was enlarged by compaction, upwarping, and subsidence occurring simultaneously during the New Madrid earthquakes.

Other areas subsided by as much as 5 meters, although 1.5 to 2.5 meters was more common. Lake St. Francis, in eastern Arkansas, which was formed by subsidence, is 64 kilometers long by 1 kilometer wide. Coal and sand were ejected from fissures in the swamp land adjacent to the St. Francis River, and the water level is reported to have risen there by 8 to 9 meters.

Large waves were generated on the Mississippi River by fissures opening and closing below the surface. Local uplifts of the ground and water waves moving upstream gave the illusion that the river was flowing upstream. Ponds of water also were agitated noticeably.

Otto Nuttli reported that more than 200 moderate to large earthquakes occurred on the New Madrid fault between December 16, 1811, and March 15, 1812 (5 of MS about 7.7; 10 of MS about 6.7; 35 of MS about 5.9; 65 of MS about 5.3; and 89 of Ms about 4.3). Nuttli also noted that about 1,800 earthquakes of mb about 3.0 to 4.5 occurred in that same period.


--------------------------------------------------------------------------------

1811, December 16, 14:15 UTC, Northeast Arkansas



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