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• Reputation: 148 Q&A: 6 0 0 28 0 0 Classifieds: 0 0 what's this? Follow Following 0 Paul Bodin

  1 0 During an earthquake we observe several different sorts of ground failures. Let's imagine the earthquake process in a couple of stages, First, driven by stressed rock, a fault plane ruptures (i.e., one side moves relative to the other). This release of elastic energy -- like a stretched rubber band, but rather stored in the stretched rocks around the fault, radiates outward as seismic waves in all directions. These seismic waves cruise outward through the rock and, near Earth's surface, interact with lots of just normal rocks and soils. But there are also pockets of soft weak soil, wet sandy muck (another technical term!), cliffs, and other topographic features. Seismic waves can cause failures in these weak features, too. So: Ground failure #1 is where a fault rupture itself intersects Earth's surface. Different types of faults lead to different detailed patterns in the faulting. But since the dominant motion of a fault rupture is shear -- the sides slide along against each other -- fault breaks aren't likely to swallow anybody up! This just doesn't happen. Ground failure #2 is related to liquefaction--where a wet sandy soil is shaken so violently that it looses cohesion and compacts--often squirting water and sand out onto the surface--and looses it's bearing capacity; buildings may list, or even fall over. If there is the slightest slope, liquefied soils will flow, and may break up into blocks. The wonderful picture of the Turnagain Heights liquefaction features in Anchorage that O my captain attached to his answer is a beautiful example of this type of ground failure. Ground failure #3 is triggered landslides. This one's easy, you shake a hillside and gravity tumbles it down. This can bury folks, like any landslide. However nothing opens up and swallows you. Yes I've spent a professional lifetime telling people not to worry, the ground WILL NOT open up and swallow you and then close again. THEN I took this picture after the ChiChi earthquake in Taiwan, 1999. My team and I couldn't figure out how---but this is the only thing I've ever seen that made believe it was possible....(!) Paul Bodin answered in Earthquake! over 2 years ago | Report 1 comment by O my captain… 0 0 I stand corrected. Thanks for the nod, but it was Mahtli that posted the photo. I just recognised it. O my captain commented over 2 years ago | Report Enter your comment or ask a new question New comments are not being accepted at this time.

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  0 0 I would say it's mostly fiction. But, check out this pic from Anchorage, Alaska in 1964. That was a 9.2 magnitude quake, making it the second largest in recorded history, and also lasted for five minutes. I'd say a repeat of that is extremely unlikely. However, this was also what's known as a "megathrust" quake, which is the same type of quake that hit this region in 1700. Mahtli69 answered in Earthquake! over 2 years ago | Report 1 comment by O my captain… 0 0 I've been there. 40 years after the quake, I walked these streets with historical photos like this one, and tried to match up the locations. What this photo doesn't convey, is that the left side of the street has slipped partially down a slope, and the resulting rebuild has all buildins along this street starting one story down (that is, you walk into the second floor from street level. THIS IS NOT A PICTURE OF A SINK HOLE. This is a hillside slip. The majority of damage in Anchorage appeared to have been slope failure and block sliding down to the shoreline. So, no Kristine, don't fear a sink hole opening up and swallowing you up. Instead, plan on where to store gear, food, shoes, water & supplies to be accessed immediately after the big one. If the building collapses, how can you reach in from the outside to retrive your earthquake survival backpack, etc. O my captain commented over 2 years ago | Report Enter your comment or ask a new question New comments are not being accepted at this time.

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  0 0 I think it can, especially if it's big enough. I think it's more likely to happen during flooding. And it can get big enough to take out a car, like the picture below, but probably not like Hollywood's 2012. That's fake. Crezman answered in Earthquake! over 2 years ago | Report Comment on this answer Enter your comment or ask a new question New comments are not being accepted at this time.

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  0 0 Judging from the beacon hill LINK tunnel and the geology lessons (unaccounted sand pockets turning into frontyard sinkholes) there about our local ground... yes there's danger ...IF you live above a LINK tunnel. =) Rev.Enant answered in Earthquake! over 2 years ago | Report Comment on this answer Enter your comment or ask a new question New comments are not being accepted at this time.

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