With just my mobile phone, I could tell in advance that something might be coming of the coast of Japan. There are apps for both the iPhone ("I Felt That Earthquake") and Android smart phones ("Latest Quakes ") that amalgamate the up-to-the-minute quake reports from the U.S. Geological Survey. The one on my Droid 2 presents the information in list form and as markers on a zoom-able/pan-able map of the world.
As I checked in from time to time over the last few weeks, I could see that the east coast of Honshu was getting hammered with fours and fives for a week before the big one. Ever since that terrifying 9.0, the same area has been seeing a five every hour or so as the earth rings like a big bell.
We all live with hundreds of quakes a day. If you look at the map display frequently, you can see patterns. (You can also imagine patterns; the human brain is tuned for that. Separating actual correlation from non- connected events is the reason we pay actuaries a lot of money.)
Many California quakes display a pattern. There's one in the sea off Fortuna; the Geysers region naturally displays seismic activity. From Chile to Alaska, to Japan, to Indonesia, the Pacific "Ring of Fire is active.
One of the most interesting correlations, which you don't need an actuary to find, is happening in Arkansas. Every day, my Droid app lists one or more quakes in the two to three range in "Arkansas." Conveniently, The app makes it possible to superimpose the markers for the last several days of quakes at any place on Earth you want to look at. If I drag the map image around to the state of Arkansas, I find that all the quakes occur exactly at the same place that looks to be about 30 miles north of Little Rock. Talk about correlation!
When I saw that happening, I was curious, so I did some Googling. Not much info is available, but the most compelling explanation to me (and, I confess, to the on-line "doomer" community) is that it's due to hydraulic fracturing, or "frac-ing." Apparently, the Arkansans are extracting natural gas in that area by injecting water into the earth to break up sedimentary rock layers. (I wrote an article once for DuPont about how they do the same thing on the oil patch. Halliburton creates the fracturing with its pumping technology, and DuPont supplies a "proppant" material that forces tiny particles into the cracks to keep them open after the pressure is relieved.)
This is not to equate what happened in Japan to the situation in Arkansas. What's going on in Arkansas is at far shallower depths than tectonic plates. but it's still weird to see all those little quakes pile up over the course of a week.
Perhaps the most fascinating thing is that you can create your own correlations in your mind with simple apps on that telephone in your pocket. The iTunes download costs a buck; the Android version's a freebie (with ads.)