Hi All. Just out of curiosity I thought I would see if large quakes do occur in clusters as it has been suggested by some seismologists. I suppose it largely depends on what your definition of a cluster is so that these quakes may be considered as a cluster then again maybe not. It just depends on your definition of what a cluster is.

There were 4 M>9.0+ quakes in the 20th Century over a 12 year period. That is an average of one quake every 3 years. When you look at the list of the quakes below you can see the 3 year average is pretty close with the last M>9.0+ in 1964.

More then 40 years later we have an M>9.0 quake. Does this mean we can have another in the next 5 years or so and if so where would that quake most likely be? I suppose it’s one of those wait and see things again. That means it’s time for me to put my feet up, sit back and wait and see what happens. Wonder how long I’m going to have to do that?

I was a little surprised and yet pleased when I learned that the miniPBOs in the Bay Area did record the quake. However I don’t know what it means. I’m still in the process of learning. Take Care…Don in creepy town

Nov. 4, 1952, magnitude-9.0, Kamchatka peninsula, Soviet Union (now Russia).

March 9, 1957, magnitude-9.1, Andreanof Islands, Alaska.

May 22, 1960, magnitude-9.5, Chile.

March 28, 1964, magnitude-9.2, Prince William Sound, Alaska.

Dec. 26, 2004, magnitude-9.0, Sumatra, Indonesia.