I am a earthquake seismologist. AMA. 5th anniversary of Louisa Quake
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Anonymous
Then how do we know "big ones" are going to hit certain areas based on data and how do we know the San Andreas fault is loaded with energy and going to pop soon - we can't predict the dates/times of earthquakes but scientists absolutely can take data and determine if a quake is going to hit within a good idea. Cmon. |
Anonymous
The author of this thread addressed this question earlier. Not sure where you get the idea that she doesn't know what she's talking about. If I asked a lawyer questions about their job, do you think they'd spit out Blue Book cites? |
Anonymous
Yes to all, but it will not happen. |
Anonymous
Not OP. The difference is geologic vs human time. The scales are so vastly different that knowing something is a near certainty to occur 'soon' in geologic terms doesn't necessarily help for disaster planning in the human time scale. Humans think of 'soon' in terms of days or maybe months and at the outside years - the Earth's definition of 'soon' is very different. |
Anonymous
| How did you end up in seismology? What degrees do you have? |
Anonymous
The OP can't predict the future. This thread was started before today's quakes. |
Anonymous
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I was in Japan a few weeks ago and they had 2 small earthquakes over the course of a few days. People treat it as normal. People have an app on their phone to show where there was an earthquake. One ocurred while I was out drinking at a bar and people just went on their usual business. Then the subways had signs, even in English, to state how strong and secure the tunnels would be during an earthquake and so on. They have sea-level elevation markers on street signs, I guess for tsunami situations so you know if you need to get to higher ground.
Are there other countries as prepared for it? What could the US do better? |
Anonymous
What are you talking about... The questions were posted AFTER the quakes happened which means the OP actually COULD discuss them. |
Anonymous
At least 75 people have died and entire towns have been leveled. How can you say 6.2 is not "big" in relation to the structures the quake is hitting. It may not be "big" compared to an 8.2, but a 6.2 can cause massive damage and kill people. |
Anonymous
The OP hasn't posted anything that shows superior knowledge on this subject. Every answer to very specific questions has been vague and very easy to find info from news reports. If I was a lawyer I could post about the laws at a level higher than the average person. OP is not doing that and hasn't addressed much. |
Anonymous
We can look at historical data to say an area is more likely to have earthquakes because we know there have been past earthquakes. In addition, plate tectonics shows us where there should be significant faults. Add in GPS data, and we can see where the earth is deforming. For example, the North Amarican plate is moving south relative to the pacific plate. In California, the slip rate is several centimeters/year. The motion concentrates on the San Andreas Fault, but includes other faults (e.g., Hayward fault, the various thrust faulting adjacent to the San Andreas Fault, the normal faulting in the Basin and Range. Putting it all together, we can say which areas are more likely to have earthquakes. Fast plate motions => more earthquakes. That is Alaska. For the probabilistic hazard analysis, we can draw maps of shaking probability. But, outside of plate boundaries, they just show where earthquakes have occurred. And because of this, we get surprised. Prior to 2004, conventional wisdom was Northern Sumatra / Andaman islands was not capable of producing a large earthquake. Then it did. Prior to 2011, the conventional wisdom was the subduction off Sendai Japan produced a maximum earthquake of 8.3. But, on March 11, 2011, that view changed over a few minutes with a 9.1 earthquake. Similarly, when I was in graduate school, there was debate that the Cascadia subduction zone off the Pacific NW was Aseismic because there were no earthquakes. Paleoseismic and paleotsunami studies, which look at geological effect to understand earthquake/tsunami history prior to written history, indicated there had been past earthquakes. As the science has progressed, particularly with ability to model tsunamis, scientists looked at the "orphan tsunami of Jan 27-28 1700": https://pubs.er.usgs.gov/publication/pp1707. This was a tsunami recorded in Japan without a known source. Modeling the tsunami arrival times and the tsunami and the amplitudes, they concluded that the orphan tsunami was triggered by a magnitude 9.0 earthquake in Cascadia on Jan 27, 1700. That is how we know the Pacific Northwest is a hazard area. The report is very easy to read, and a wonderful combination of combing through historic reports coupled as data to feed into modern computer simulations. Anyway, that is how we know which areas are more likely to have an earthquake. |
Anonymous
I was interested in it. BS in Geophysics, MA/PHD in Geological Sciences (but work was in geophysics) |
Anonymous
Big is defined by energy release. 6.2 is not that big. Killing people is not what defines the size of an earthquake. Rather, it is the energy (or more accurately) moment release of the earthquake, not the human effects. The human effects can be mitigated with proper construction techniques. |
Anonymous
What triggered your interest? Did you know going into undergrad? Have a class that sparked something? |
Anonymous
I am trying to answer the questions at a level so that the average person can understand. I could talk about focal mechanisms, moment tensors, finite fault inversions, radiated energies, geophysical inversion, but that will not help in the understanding of the field. I thought this would be fun to do on the 5th anniversary of the Lousia Earthquake. I had no idea the Italy or Burma quakes would happen. Oh, and yes, you can find most of the information on line. As a discipline, seismology is extremely good at sharing data and reports. We understand the fear of earthquakes. We try to educate the public. For example, you can get data from many seismic stations globally through an NSF funded university consortium, IRIS (http://www.iris.edu). The data is as recent as 10 seconds old. |