Edit - Earth Science Stack Exchange - 江南体育网页版

You are notlogged in. Your edit will be placed in a queue until it ispeer reviewed.

We welcome edits that make the post easier to understand and more valuable for readers. Because community members review edits, please try to make the post substantially better than how you found it, for example, by fixing grammar or adding additional resources and hyperlinks.

可以两次大地震发生在s /三次吗ame place within a short timeframe

I want to know if large earthquakes can happen twice in the same region? The reason is that the recent earthquake in Nepal was followed by many after shocks of considerable magnitude.

I wanted to know if there are chances of earthquake of this magnitude in the same region again. Can we expect another earthquake in the same region, lets say in a month or few months?

Answer

It can happen but not like you may guess. I believe you have seen rupture maps for large earthquakes, such as the 2011 Japan earthquake. In that earthquake, a foreshock of 7.3 took place at the perimeter of the area of largest slip during the main earthquake. This could be interpreted like this (using the asperity model): the foreshock hit at the "slopes" of the asperity but failed to "climb" up immediately; aftershocks were slowly migrating towards the "top" of the asperity, then the main shock happened. Furthermore, once the whole fault was activated, slip at the shallowest parts went beyond charts (40, 50, even 80m of slip were reported locally). The main (deep) asperity had the fewest aftershocks (it slipped completely and without restraints), but there were enough of them in the shallowest parts of the fault. This is probably because the shallower slip was not due to an asperity but rather due to diffused slip of unconsolidated sediments (the "bookshelf" model was used, plus there were aftershocks that appeared to actually... pull back the pieces closer to their original locations). Anyways let's focus on the deeper asperity. An earthquake can take place at the "slopes" of a large asperity but fail to rupture towards the "top" It can however rupture towards the perimeter and achieve respectable sizes. Then another earthquake can take place nearby, but still low at the "slopes". Finally an earthquake can climb over the top and force even the previously ruptured areas to re-rupture. All 3 earthquakes can very well have epicenters pretty close to one another (such as the two eastern Nepal aftershocks recently). It seems that the 1960 huge Valdivia earthquake demonstrated this behavior but I have yet to find a good, detailed, open-access study on it. Concerning Fred's answer, unfortunately [Bilham](http://cires1.colorado.edu/~bilham/2015%20Nepal/Nepal_2015_earthquake.html) (he mentions Jones and Molnar, 1986) (search for "preceded") says that 10% of strong earthquakes in the history of Himalaya have been preceded by strong shocks. Other sources support Fred's answer, but I would choose to believe Bilham. Concerning the "lots of aftershocks" notice that the author of the question pointed, for a given earthquake with a normal aftershock sequence it is expected that its strongest aftershock is 1.2 magnitude smaller than the mainshock. For this case, this would yield 6.6. In fact, the strongest ones were the 7.3, an 6.7 and a 6.6, so yes this is anomalous, but the empirical 1.2 value I mentioned is a bit smaller for Himalayas. Still, an 7.3 is anomalously large but *before* that time we had no reason to suspect an anomalous aftershock sequence (to my knowledge of course, I searched for b-values but did not find anything during the first days of aftershock activity).

Edit Summary

Cancel

Add a comment |

Correct minor typos or mistakes
Clarify meaning without changing it
Add related resources or links
Alwaysrespect the author’s intent
Don’t use edits to reply to the author

create code fences with backticks ` or tildes ~
```
like so
```
add language identifier to highlight code
```python
deffunction(foo):
print(foo)
```
put returns between paragraphs
for linebreak add 2 spaces at end
_italic_or**bold**
quote by placing > at start of line
to make links (use https whenever possible)

[example](https://example.com)
example
MathJax equations $\sin^2 \theta$

formatting help »
answering help »

MathJax help »