Geologists Say California May Be Next 258
Hugh Pickens writes "Newsweek reports that first there was a violent magnitude-8.8 event in Chile in 2010, then a horrifically destructive Pacific earthquake in New Zealand on February 22, and now the recent earthquake in Japan. Though there is still no hard scientific evidence to explain why, there is little doubt now that earthquakes do tend to occur in clusters: a significant event on one side of a major tectonic plate is often — not invariably, but often enough to be noticeable — followed some weeks or months later by another on the plate's far side. 'It is as though the earth becomes like a great brass bell, which when struck by an enormous hammer blow on one side sets to vibrating and ringing from all over. Now there have been catastrophic events at three corners of the Pacific Plate — one in the northwest, on Friday; one in the southwest, last month; one in the southeast, last year.' That leaves just one corner unaffected — the northeast. And the fault line in the northeast of the Pacific Plate is the San Andreas Fault. Although geologists believe a 9.0 quake is virtually impossible along the San Andreas, USGS studies put the probability of California being hit by a quake measuring 7.5 or more in the next 30 years at 46 percent, and the likelihood of a 6.7 quake, comparable in size to the temblors that rocked San Francisco in 1989 and Los Angeles in 1994, at 99 percent statewide."
Re:9.0 magnitude earthquake Unpossible? (Score:3, Informative)
>>>The link doesn't explain why the San Andreas fault can't have a 9.0 magnitude earthquake
Quote: "Geologists believe a 9.0 quake is virtually impossible along the San Andreas, a network of "strike-slip" faults smaller and more fragmented, than the great chasm that exists where two continent-sized plates of the Earth's crust meet along the Japanese islands."
"This subduction zone beneath the Pacific, where one tectonic plate is thrust up over another, is capable of producing the biggest quakes on Earth, on an order of magnitude higher than any recorded in California."
Economist Article (Score:4, Informative)
There was an article in the Economist on this issue this week. The potential for a really big Earthquake lies further north off the cost of Washington State and British Columbia.
http://www.economist.com/blogs/babbage/2011/03/megaquakes
Re:9.0 magnitude earthquake Unpossible? (Score:5, Informative)
Re:What about New Nadrid (Score:4, Informative)
And the nuclear plants will be fine. If you check, there were 4 power plants, each with multiple reactors, near the site of the Japanese 9.0 quake. All of those reactors shut down normally and survived the earthquake.
Only one of those sites is having any trouble -- and it is only because an 8m tall wall of water topped their tsunami protection wall (it was designed to stop a 6m tsunami). The water knocked out their connection to the power grid, flooded their backup generators AND the backup backup generators. It also damaged many of the electrically driven pumps. Fukushima Dai-ichi is a rare case where, due to an essentially unforeseeable event, a single cause destroyed the primary power connection, primary cooling pumps and all of the backup systems simultaneously.
You can be sure that once the situation in northern Japan is stabilized, changes will be made. Now that they know an 8m tsunami is possible they will upgrade all of the tsunami barriers over the next decade or two.
Re:9.0 magnitude earthquake Unpossible? (Score:4, Informative)
Actually, we've been expecting a magnitude 8+ for the last 30 years, and probably more, I can recall the last 25 of those years. At this point it's likely approaching a 9. We've only had a magnitude 5.3 and a 6.8 in the last 15 years or so on top of the regular minor earthquakes. So, we are very much aware that we're due for one.
OTOH, our mayor McJackass seems more concerned with killing our tunnel than with replacing the viaduct that we've known will go down in an earthquake ever since the Loma Prieta quake did the same thing to 880.
Re:Blame it on the solar cycle (Score:5, Informative)
It's very likely that there were more than eight 8.5+ magnitude earthquakes before 1900. The Wikipedia you reference says "(est)" after those quakes because reliable global earthquake monitoring only started in the last century. Those eight quakes are famous and, deadly, and most importantly, directly affected (and killed) Europeans. The magnitudes were estimated from historical records.
There were certainly many more large earthquakes between 1700 and 1900, but they weren't recorded.
A little more info on large quakes (including references to the sources for the data on large earthquakes since 1900) here, if you're interested: USGS list of 8.5+ magnitude earthquakes since 1900 [usgs.gov]