quake could be mad powerful

big earthquake could really be BIG

heh, if i lived in LA, i'd be finding a flat area, in the middle of nowhere. or at least away from buildings.

Can this be the infamous earthquake that will part California into a whole bunch of mini islands.

altough it'd be really hard to activate all the fault lines in california, and then to a level where'd it shake it to the sea.

i belive the madre and san andreas faults could be significant, in like said, if they trip one an other, it could REALLY jack things up. not to mention madre and san andreas are pretty close to LA.

I posted a thread a while back (dont remember what I called it) about a new type of splay fault line they found under the San Andreas.

Before I read this, I would have said that the largest EQ to be possible in California would have been around 7.5 or so, mainly because the rock units comprising the San Andreas have been so fractured as to not be capable of containing very large amounts of energy before rupturing.

These newly found splay faults do in fact allow much higher levels of energy to be maintained, and EQs triggered from these faults are going to be much deeper than from the San Andreas, therefore can cause much wider spread damage.

I am still worried about the New Madrid fault zone, mainly because it is so deep, contains similar splay faulting, and has been largely inactive for almost 200 years, therefore has stored MUCH more energy than the San Andreas. In addition, there is evidence that the splay faults associated with the New Madrid may extend northward, and possibly interact with known fault systems, and in a really large (8.0+) EQ, might trigger quakes in Chicago.

PC, your best bet for survival in this situation doesnt neccessarily involve flat ground. Consider that Oakland Ca was nice and flat, and was totally destroyed, because it was on top of nothing but deep sedimentary deposits that allowed enormous resonant waves to build up, almost like waves in the ocean. Your best bet is to find someplace on solid rock.

here's an idea, get up in a helicopter once stuff starts shakin and watch it!

then go and raid the ruins of all the banks and kwik e marts and get the hell outta there!

Well it looks like I 'm gonna be moving soon.

No offence to anyone in Cali, but thats one state I just wont live in, for that very reason. Also, as much as I love KY and TN, I wouldnt live there, except maybe the far east end of the states.

Originally posted by dragonrider
No offence to anyone in Cali, but thats one state I just wont live in, for that very reason. Also, as much as I love KY and TN, I wouldnt live there, except maybe the far east end of the states.

I don't blame ya there DR. I would love to do some geotech work in Cali. but wouldn't want to know my family was there. The NMSZ does worry me a bit but not so much for physical damage to the area in KY where I live as much as the economic damage the entire state would suffer.

I live on the outer knobs region just South of Lexington where we have mostly A-6 and A-7 clayey soils so we wouldn't expect near the damage as the Western part and the Jackson Purchase area with their A-2 and A-4 silts.

KY Lake and Lake Barkley dams are the big danger. Combined with the lowland elevations and the Mississippi River, flooding would almost certainly be the biggest risk.

Although I'm not that worried, I did elect to keep my office on the basement floor when offered one on the second floor. Plus at home, I'm in process of trying to shore up the basement supports and beams so a large quake might not move my whole first floor into the basement. I keep hoping to get a hold of some elastic bearing pads like we set bridge beams on (don't use steel rockers anymore). Wish someone would test some and get a few extra.

Astrocreep,
You're in KY too? You seem to know the soil types in our fair commonwealth, what the heck do I live on in Louisville! I'm I safe..... is anyone safe....

What is your and DR's guesstimation on when an event might occur in the NMSZ?

Observer, hello fellow Kentuckian. Louisville is hard to say. Most samples I've done from there actually fall between a silt and a clay. See, the Ohio river was formed by glacial outwash of the Illinoian Ice Sheet so some soil is residual (weathered from rock under it) and some is outwash and some is consolidated by weight of the ice sheet in the Louisville Area. Most of Jefferson county rock structure falls under the Devonian Era. I'll give ya an interesting link. Here's the two paragraphs I find that most answer your question;

"Seltersburg and Jeffersonville Limestones (Dsj).-Exposures of this carbonate sequence are thickest in the vicinity of the Falls of the Ohio in Jefferson County, where the thickness reaches 50 ft. Three main units represented are the Jeffersonville Limestone and the Silver Creek and Beechwood Limestone Members of the Seltersburg Limestone."

Which is good and stable but...


"The basal unconformity truncates rocks ranging in age from Late Ordovician on the crest of the Cincinnati arch to Middle and Late Silurian on the flanks of the arch. In most exposures, this unconformity appears planar, as in the vicinity of Jefferson County, where it can be followed without interruption for nearly a mile along the north side of Interstate Highways I-71 and I-264. Where the unconformity truncates rocks of contrasting hardness, as in south-central Kentucky (Simmons, 1967; Kepferle, 1973), the Devonian carbonates and shales are thick over easily eroded Silurian shale but thin over nearby Silurian-dolomite capped cuestas or monadnocks."

The fly in the ointment as they say. The key word in the second quote is "planar" It means semi-smooth and allows rocks to slide by each other with minimum friction.

So thats hard to say what the effect would be depending on the mag. If this unconformity slides, I-265 and I-71 might be unusable. And as fond as I am of the Old Watterson Expressway, that would severly hinder emergency transportation in the Metro Area.

Anyway, here's the link I used and thanks for the question, you might have just given me an idea for a new research project! I'd say this is a question which really needs answering considering that its the biggest city we have now.


pubs.usgs.gov...


On a side note, link to NMSZ region of KY.

www.uky.edu...

www.uky.edu...


[Edited on 19-5-2003 by astrocreep]

[Edited on 19-5-2003 by astrocreep]

Holy MOLY Astrocreep, you MUST be either a Geology grad student at UK or a geology Prof at UK. Thanks for the info....it will take the History grad student from UL weeks to decifer though.

I glean that it might be safe to live in Anchorage but my part of town is a big question mark!

Originally posted by observer
Holy MOLY Astrocreep, you MUST be either a Geology grad student at UK or a geology Prof at UK. Thanks for the info....it will take the History grad student from UL weeks to decifer though.

I glean that it might be safe to live in Anchorage but my part of town is a big question mark!

No, not hardly. I do work for a geologist but my degree is related. I've sit through enough presentations about this and sifted enough soil til' sometimes I wonder if there could be any left in the state. Most of my work is transportation research related so I don't get to get into this juicy stuff too much. Its like having a bushel of apples and being the stem taster. I think there is a lot of aspects reguarding slopes we could be exploring but most of the earthquake stuff is handed to the structural people for obvious reasons.

Astrocreep:

I am thinking you are working for a geotech consulting firm. I did that for more than a few years, and cut my teeth on geology while I was in school taking blow counts and calculating rock competencies. Keep it up, its not the most glamorous of jobs, but you are getting a good deal of experience!

(When I was training, went out with our senior geologist. I decided to have some fun with him. We were driving split spoons in deep native clay, and when i took the spoon off the hammer, I slipped a bottle cap in the end. When he popped the spoon open and found that, he spent an hour trying to decide if he was in fill or not )

Observer, as far as when a serious seismic event might take place in the New Madrid, who knows? It has been relatively quiet for almost 200 years, and quite frankly, that is what worries me.

In the San Andreas, it releases a good sized 6.0-7.0 every 10-20 years, and essentially blows most if not all the energy it has stored. Dont worry so much about a seismic zone if it is active on a regular basis, as that activity doesnt allow it to build up dangerous levels of energy. When a seismic zone is quiet for decades or centuries, it is building up enormous amounts of energy.

In addition, the New Madrid is composed of much more competent rocks than the San Andreas, meaning the rocks are much more solid, stronger, and capable of containing much higher energy levels. Consider that a quake doesnt occur until the stored energy exceeds the strength of the rocks.

Certainly, monitor the seismic activity there in the New Madrid. There are likely to be some foreshocks before a massive quake. However, when you look and find that the New Madrid regularly releases very small 3.0 shocks on a regular basis, it is hard to identify a true foreshock.

Gee thanks DR... I feel much better now

Got a website that i can look to every once in while to see activity on the NM?

This is the only one I have on my list that is specific to the NMSZ. Most of my links are worldwide for quakes. If you find one, please let me know though!

Sorry its not the most user friendly of the bunch.

www.eas.slu.edu...

Originally posted by dragonrider
This is the only one I have on my list that is specific to the NMSZ. Most of my links are worldwide for quakes. If you find one, please let me know though!

Sorry its not the most user friendly of the bunch.

www.eas.slu.edu...

That works DR, thanks. Looks like in the last 14 days we have had a few 2.0 magnatudes at a depth of less than 100 km. I'm I reading this right?

Thats what it looks like, although I dont know how often it is updated.

The depth is worrying, but the magnitude isnt.

Observer, here is the closest station monitoring the New Madrid I can find. Its in Fulton County, KY which is the border county of KY / MO. I drilled there a month one week. Lotsa corn fields a but some damn good BBQ.

www.uky.edu...


Also, here's the full list done by the KY Geologic Survey so you can look at other real-time data across the state. To see how the shock wave travels, we can compare the strength form a closer area to one say in Louisville the next time they have a moderate one.


www.uky.edu...

Originally posted by dragonrider
Astrocreep:

I am thinking you are working for a geotech consulting firm. I did that for more than a few years, and cut my teeth on geology while I was in school taking blow counts and calculating rock competencies. Keep it up, its not the most glamorous of jobs, but you are getting a good deal of experience!

(When I was training, went out with our senior geologist. I decided to have some fun with him. We were driving split spoons in deep native clay, and when i took the spoon off the hammer, I slipped a bottle cap in the end. When he popped the spoon open and found that, he spent an hour trying to decide if he was in fill or not

)

Observer, as far as when a serious seismic event might take place in the New Madrid, who knows? It has been relatively quiet for almost 200 years, and quite frankly, that is what worries me.

In the San Andreas, it releases a good sized 6.0-7.0 every 10-20 years, and essentially blows most if not all the energy it has stored. Dont worry so much about a seismic zone if it is active on a regular basis, as that activity doesnt allow it to build up dangerous levels of energy. When a seismic zone is quiet for decades or centuries, it is building up enormous amounts of energy.

In addition, the New Madrid is composed of much more competent rocks than the San Andreas, meaning the rocks are much more solid, stronger, and capable of containing much higher energy levels. Consider that a quake doesnt occur until the stored energy exceeds the strength of the rocks.

Certainly, monitor the seismic activity there in the New Madrid. There are likely to be some foreshocks before a massive quake. However, when you look and find that the New Madrid regularly releases very small 3.0 shocks on a regular basis, it is hard to identify a true foreshock.

DragonRider, Nope, I don't work in the private sector and its been a while since I've done much drilling. I think a couple years and that was just into the subgrade under the roadway to test lime-treated soil. I do mostly transportaion type research and evaluate slides and rockfall hazards among other things. I mainly take care of soil classification tests like CBR, Particle size and Plastic index tests in the lab. We are also pioneering some testing in resilient modulus of soils which everybody seems gaga about but I find a snoozer. In the field, I handle mostly the GPS/GIS systems and manage all that data. In fact, I'm heading out the door here in a second to do some of that.

Like I said before, we've been wanting to do some earthquake studies in West KY but no-one seems too worried about the embankments just the structures. I'm afraid we are going to find out that bridges don't help much when half the highway falls away. Maybe the military with their hummers can traverse it but regular autos will have a time of it.

And your joke was hilarious. Mind if I steal that one from you? The next time we put a hole down and drive a spoon or push a Shelby tube, I'll do it.

you should all come to england!! the most dangerous thing here is lowlifes walking around with knives and chasing you if you look at them. its so FUN!! the weather.... the famous british weather, ya gotta love it.