The United States Geological Survey has vast data on earthquakes. I looked at their “Largest and Deadliest Earthquake” list, which spans 1990 to 2011.
I looked at just those quakes on the Pacific Ring of Fire. I was looking to see if there was an increase in frequency and/or magnitude over the past 21 years.
There were a total of 31 “largest/deadliest” earthquakes on the Pacific Ring of Fire. The magnitudes ranged from 6.3 to 9.1 Richter scale. It looks like the amount of activity is spread evenly over the past 21 years, but it’s deceptive. From year to year the pattern of activity is interesting.
1990 one, 1991 two, 1992 one, 1993 one, 1994 two, 1995 three, 1996 one, 1997 two, 1998 one, 1999 one. At this point it looks like there is a loose pattern; 1/2/1/1/2/3/1/2/1/1.
2000 two, 2001 one, 2002 one, 2003 one, 2004 two, 2005 one, 2006 two, 2007 two, 2008 zero, 2009 two, 2010 one, 2011 two. The pattern is different; 2/1/1/1/2/1/2/2/0/2/1/2.
Where the most quakes hit changes as well. In the 1990s Japan was hit by one large/deadly quake. From 2000 to 2011, Japan has been hit by two large/deadly quakes. But check out Indonesia. In the 1990s the Indonesian islands were hit with two large/deadly quakes. From 2000 to 2010 the Indonesian islands suffered six large/deadly quakes. On the Americas side of the Pacific Ring it looks like quakes are more evenly spread out over the years. From 1990 to 2011 a total of eight large/deadly earthquakes were spread from Alaska to Chile.
What is clear is that the activity is more frequent, and stronger, on the Asian side of the Pacific Ring (probably because that’s where the Pacific plate slams under the Eurasian plate). But that’s no reason not to prepare, if you don’t live on the Asian side.
Note: The Japanese islands and the Indonesia islands are affected by several plates. Japan sits on the Eurasian plate, which is being hit by the Pacific plate and Philippine plate. Indonesia straddles the Eurasian and Philippine plates, which are getting hit by the Pacific plate.