I would assume someone new to CA would find it concerning.

It's fun to think about it - some Japanese people would move to CA just because of the more stable geology.

> The U.S. Geological Survey's most recent forecast, known as UCERF3 (Uniform California Earthquake Rupture Forecast 3), released in November 2013, estimated that an earthquake of magnitude 6.7 M or greater (i.e. equal to or greater than the 1994 Northridge earthquake) occurs about once every 6.7 years statewide. The same report also estimated there is a 7% probability that an earthquake of magnitude 8.0 or greater will occur in the next 30 years somewhere along the San Andreas Fault.

~ https://en.wikipedia.org/wiki/San_Andreas_Fault#The_next_%22...

I question their research skills. I would avoid California if geology was my main motivator.

▲

kijin 8 hours ago | parent [-]

There is an 80% probability that an earthquake of magnitude 8-9 will occur in the Nankai trough (massive subduction zone along the Pacific coast of Japan) in the next 30 years. Yes, you read that correctly. Eighty percent. It's almost a certainty.

San Andreas sounds like nothing by comparison, especially since it doesn't pose as much of a tsunami risk.

▲

dredmorbius 5 hours ago | parent [-]

It's also worth noting that a mag 8 is about the maximum expected from the San Andreas fault, a strike-slip fault, and most quakes come in well under that. The two largest quakes I'm aware of, the 1906 San Francisco and 1857 Fort Tejon quakes, were mag 7.8 and 7.9 respectively.

Significant damage can be experienced starting at about mag 6, though that tends to be pretty specific (individual structures, often pre-dating earthquake codes, and locations on poorly-suited terrain such as riverbottoms, reclaimed wetlands, or sand). Widespread general damage would only be experienced with larger quakes (mag 7--8).

Japan has a significantly higher risk of mag 8--9 quakes. The 2011 Tōhoku quake was a magnitude 9, which is 100 times more powerful than a mag 7, and over 100,000 times more powerful than this morning's temblor in Berkeley. Japanese faults include subduction zones and considerable tsunami risk.

Similar risks exist between the California-Oregon border through to British Columbia on the Cascadia Subduction Zone, and could similarly product a mag 9 event.

<https://en.wikipedia.org/wiki/UCERF3>

<https://en.wikipedia.org/wiki/Cascadia_subduction_zone>

▲

jandrewrogers 5 hours ago | parent | next [-]

> a magnitude 9, which is 100 times more powerful than a mag 7

That is actually 1,000x more powerful. For historical reasons, the magnitude scale is 10^1.5 between whole numbers.

▲

kijin 5 hours ago | parent | prev [-]

The Cascadia earthquake in January 1700 produced a tsunami that traveled all the way across the ocean and hit Japan with 16-foot waves. That's what mag 9 looks like.

	▲	saltcured 4 hours ago \| parent [-]
		Similarly, the Boxing Day tsunami in 2004 was from a 9.1 magnitude quake in Indonesia.

▲

bamboozled 8 hours ago | parent | prev [-]

Why would Japanese people move to CA for the more stable geology ?

	▲	ChrisMarshallNY 8 hours ago \| parent \| next [-]
		Japan is one of the most seismically-active areas in the world. As a result, [modern] Japanese construction is incredibly resilient. I've never been in Tokyo, during a strong quake, but I'm told the skyscrapers wave around like drunken dancers.
	▲	0manrho 7 hours ago \| parent \| prev \| next [-]
		It's a point of comparison to illustrate the differences. CA is seismically active, but not to the degree of Japan. Reading any further into it than that was clearly not the intent and would be foolish.
	▲	notmyjob 8 hours ago \| parent \| prev [-]
		Because there are no longer any other good reasons to move here.