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Is there any possibility that the West Coast of USA will have a strong earthquake in the next 5-10 years?
Question Date: 2019-10-18
Answer 1:

Yes, it is possible that the West Coast will have a strong earthquake in the next 5-10 years. It is not possible to accurately predict when and where an earthquake of a particular magnitude will occur, but you can calculate the probability of one, based on what has occurred in the past.

For example, according to the United States Geological Survey, for the Los Angeles area over 10 years’ time, there is a 20% chance of a magnitude 6.7 earthquake, a 15% chance of a magnitude 7 earthquake, and a 10% chance of a magnitude 7.5 earthquake. Since it is not possible to predict when an earthquake will actually occur, if you live in an area prone to earthquakes, you should always be prepared for one by practicing and keeping emergency supplies just in case.

Answer 2:

Without question. There is ALWAYS a non-zero probability that a strong EQ will occur along the western coast of the US within the next 5-10 years. But, that's a VERY small bit of time (geologically-speaking). So geologists look at trends on longer (but still human-length) timescales instead. Most probability estimates are based on a 30-year forecast model (see below figure).


I took the above screenshot from the 3rd Uniform California Earthquake Rupture Forecast, which was produced by the USGS (you can find it here .)

Answer 3:

There is a good possibility that the West Coast of the USA will have a strong earthquake in the future. This is because the west coast of the USA is at the edge of a tectonic plate.

When earth scientists estimate the chance of an earthquake, it is very hard to say when exactly an earthquake will occur. We can predict that an earthquake will happen in the next 100 years, but it's very hard to predict if it will happen in the next 5-10 years.

Here is a photo from NASA showing all the tectonic plates in the world. Anywhere where there is a plate boundary (edge of a plate), there is a higher chance of "activity" (volcanoes or earthquakes). The west coast of USA is right along a plate boundary, so we can predict it will have a higher chance of earthquakes than the interior USA.

This photo is from a website by nasa, which has a ton of cool photos and explanations of how faults and plates cause earthquakes: here.

Answer 4:

Yes, the west coast contains many faults (the San Andreas being one of the most famous). These are areas where the earth’s plates are in close contact. While the surface of the earth seems stationary, the plates actually are continuously moving (just very slowly). As they move, they can get caught on one another, building tension. Once this “snag” breaks free, the tension is released, causing an earthquake.

Imagine you are walking down a side walk and your shirt gets caught on a fence. Once it gets caught, you feel a lot of resistance. If you keep walking forward, fighting the resistance, you will eventually break free, but as soon as you do, you will fly forward. This is essentially what is happening with the plates, they get caught, keep trying to move, and eventually break free causing a jerking force (earthquake). Building form this, the longer they are caught without breaking free, the more force will be built up, so once they do eventually break free, the earthquake will be stronger. This is not a universal truth, but generally speaking, the longer the west coast goes without any small earthquakes, the more likely it is the next earthquake is large.

Answer 5:

Yes. At earthquake faults, there is a small probability [a small chance] that large earthquakes will happen - large earthquakes don't happen very often.

There's a middle-sized probability that middle-sized earthquakes will happen - middle sized earthquakes happen sometimes. There's a high probability that little earthquakes will happen - little earthquakes happen often.

We don't know when the next strong earthquake will happen.

Answer 6:

Yes, although it is difficult to say how likely it is. It also depends on what a "strong" earthquake means (i.e. how strong is strong?).

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