Is Oklahoma OK?

[other one]

One of our sundayschool teachers lived in Califirnia for a long time and he told us that he had been in upper 6's and low 7's that were not as voilent as this one was here in Shawnee. We do have building damage and road damage and houses north of here that are completely going to have to be totaled. We have a retired missionary that lives here and he had brick walls collapse and thier celiing fell in. Our house is about 70 years old and it built pretty well though it's kind of weird the way it's put together. We have raised hardwood floors with a crawl space under and some of our supports for the flooring are laying on the ground and we do have some cracks in some of the older walls that are stil plaster and not dry wall. We did seem to come out better than some of our neighbors. One of the buildings at a college here (St Gregories) lost a large steeple and damaged a second one. There are four and no telling of the damage done to the rest of the building.

I'm not sure exactly how those size ratings are figured, but we seem to have a lot more damage than other places I've read about. It seems to me that most 5.x's don't really cause much damage.... We don't have a lot of earthquake codes here though.

[nChrist]

My wife and I felt the last quake at about 2250 last night. It felt like someone pushed our chairs. We live in Southwest Oklahoma 70 miles or more away from the epicenters. We haven't heard of any major damage here. The comments about the lack of building codes for earthquakes is accurate as far as I know in this part of the country. At the very least, my wife and I were reminded of the major fault line that we live about 18 miles away from.

[jmlusa2000]

I live in Lawton, Oklahoma, and I did feel the quake last night shortly before 2300. It felt as though a big train hit the building. I was putting away laundry in my room. I sorta lost my balance, then a few minutes later I felt a smaller tremor that made my feet and legs vibrate. There are no damages, and no injuries in this area of Oklahoma. A few people are reporting cracks in their ceilings and pictures knocked off the walls. A few people have reported water main breaks. Thank you everyone for keeping us here in Oklahoma in your prayers. Please continue to pray. Severe weather and tornadoes are possible tomorrow.

[ayin jade]

I am not an earthquake expert, but I do pay attention at times. From what I saw last night on the govt quake website, this one was pretty shallow, all of 3 miles deep. Other quakes in my memory are upwards of 20 miles deep. I know that depth and amplitude have something to do with severity of quake effects as well as the way buildings are built in quake zones.

[nebula]

I don't recall out 5.8 earthquake last August causing much structural damage to homes. I'm puzzled at the comparison?

Depends on the building. Brick does not bend, it breaks. Wood flexes with shock and does not break. This was learned during the 1906 San Francisco quake. There are more brick buildings in the Midwest and the east by far then in California. You see I have noticed this as It sorta freaked me out seeing so many brick buildings, I noticed it when I moved to Denver and when I visited my friends in Pennsylvania. Along with a few documentaries about the potential for major disaster because the mid west has some major faults that go very rarely and they shake the bedrock worse then it does in California, and they have no real earthquake building code, so when they do have even a stronger little earthquake they suffer much more damage then in California.

Neb it has to do with the strata as well as the building composites. Here in the East the quakes are dampened a bit due to the strata at least that's what I recall hearing.

I am not an earthquake expert, but I do pay attention at times. From what I saw last night on the govt quake website, this one was pretty shallow, all of 3 miles deep. Other quakes in my memory are upwards of 20 miles deep. I know that depth and amplitude have something to do with severity of quake effects as well as the way buildings are built in quake zones.

OK - thanks!

[Guest]

Why do some earthquakes cause more damage than others?

Earthquake's release compressional shear and surface waves with the surface waves being the slowest and most destructive. Depending on the material the Surface waves (Love and Rayleigh waves) pass through they will increase or decrease in amplitude or frequency. Bedrock or solid material decreases the amplitude and frequency of these waves causing less overall shaking. Unconsolidated sediment however increases both amplitude and frequency causing more violent shaking. This is why there can be pockets of more destruction and less destruction depending on the underlying stratigraphy.

Buildings also oscillate at a certain frequency i.e. Tacoma narrows bridge (galloping girde) so if the frequency that the seismic waves are oscillating at match the buildings frequency it will cause it to engage in harmonic motion and eventually tear itself apart. Smaller or shorter buildings tend to have higher frequencies whereas larger skyscrapers will oscillate at a lower frequency.

Read more: http://wiki.answers.com/Q/Why_do_some_earthquakes_cause_more_damage_than_others#ixzz1cyn71Sgx

~

Introduction: Seismic wave animations are used to illustrate different types of wave propagation through elastic materials. Animations are provided to view wave propagation in a 3-dimensional solid for Compressional (P), Shear (S), Rayleigh ® and Love (L) waves. Wave characteristics and particle motions of these wave types can be easily illustrated using the seismic wave animations.

~

Types of Seismic Waves

There are several different kinds of seismic waves, and they all move in different ways. The two main types of waves are body waves and surface waves. Body waves can travel through the earth's inner layers, but surface waves can only move along the surface of the planet like ripples on water. Earthquakes radiate seismic energy as both body and surface waves.

http://www.geo.mtu.e...Seis/waves.html

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Analyses of earthquake damage in Washington and elsewhere suggest that the severity of shaking depends on several factors besides the distance and magnitude of an earthquake. (See Structural Failure of Buildings) These factors include the kinds and thicknesses of geologic materials exposed at the surface and the subsurface geologic structure (Rasmussen and others, 1974; Newman and Hall, 1982). Natural and artificial unconsolidated materials, such as sediments in river deltas and materials used as landfill, commonly amplify ground motions relative to motion in consolidated sediments or bedrock. Such areas, in general, have had higher levels of ground shaking in past Washington earthquakes. The thickness of unconsolidated material may also affect the amount of ground shaking produced. Certain frequencies of ground shaking may generate disproportionately large motions because of wave resonance in sedimentary basins. Just as the pitch of sound from an organ pipe depends on the length of the pipe and the density and compressibility of air, the various frequencies at which a sedimentary basin will resonate when shaken by seismic waves depend on the thickness, density, and stiffness of the sedimentary layers.

Subsurface structures, such as sedimentary layers that vary in thickness or degree of consolidation, may increase ground motion by focusing seismic wave energy at a particular site. The curved surfaces of buried bedrock topography may also focus waves. Langston and Lee (1983) suggested focusing as a mechanism to explain why the severity of damage observed in West Seattle during the 1965 Seattle-Tacoma earthquake seemed unrelated to surface geology in many places (Mullineaux and others, 1967; Yount, 1983). The depth to bedrock changes from very near the surface in the West Seattle area to significantly deeper just a short distance away in downtown Seattle.

[jmlusa2000]

I am not an earthquake expert, but I do pay attention at times. From what I saw last night on the govt quake website, this one was pretty shallow, all of 3 miles deep. Other quakes in my memory are upwards of 20 miles deep. I know that depth and amplitude have something to do with severity of quake effects as well as the way buildings are built in quake zones.

smart Jadey.

[mizzdy]

One of our sundayschool teachers lived in Califirnia for a long time and he told us that he had been in upper 6's and low 7's that were not as voilent as this one was here in Shawnee. We do have building damage and road damage and houses north of here that are completely going to have to be totaled. We have a retired missionary that lives here and he had brick walls collapse and thier celiing fell in. Our house is about 70 years old and it built pretty well though it's kind of weird the way it's put together. We have raised hardwood floors with a crawl space under and some of our supports for the flooring are laying on the ground and we do have some cracks in some of the older walls that are stil plaster and not dry wall. We did seem to come out better than some of our neighbors. One of the buildings at a college here (St Gregories) lost a large steeple and damaged a second one. There are four and no telling of the damage done to the rest of the building.

I'm not sure exactly how those size ratings are figured, but we seem to have a lot more damage than other places I've read about. It seems to me that most 5.x's don't really cause much damage.... We don't have a lot of earthquake codes here though.

It depends on the soil, bedrock and all that. I lived all over So.Cal and was in a lot of earthquakes. What I found is that even the quakes in the LA/Anaheim regions felt different than in the upper deserts of the state, and even some of the same size quakes are different depending on the fault.

[other one]

Ok, so we had another one (4.7) this time about an hour ago. It shook about as much as the 5.6 last night, but only felt it for about 15 seconds this time. Heliplots showed it lasted for about a minute but the last part wasn't strong enough to feel.

So, we are having tornado watches and warnings....... how safe is it to be in a cellar with 10 tons of concrete over your head in an earthquake..

[~candice~]

I'm just waiting for someone, anyone, to come up with the hypothesis that Oklahoma somehow sinned against God and this is His divine judgement. Oh and Christmas Trees, where oh where has that pesky thread gone, oh where, oh where can it be?

On a more serious note, I'm glad everyone is OK .