Sent to you by moya via Google Reader:
It does seem like there have been a lot of major earthquakes in recent years, but the fact remains that the Earth is geologically active and currently tectonically unstable, meaning that the crust has not solidified and is still in motion. Earthquakes of all magnitudes are going on repeatedly around the world, and monsters of the size that struck Haiti last year and Japan this year, are not uncommon, though mainly they are confined to distant locations offshore, near major subduction zones.
Japan, being near the boundaries of two crustal plates (part of the well-known "Pacific Ring of Fire") is susceptible to earthquakes, and as such, this event, other than its sheer magnitude, is not unusual. The reason for earthquakes of such high Richter numbers is a tremendous amount of tension built up as crustal plates rub against each other. Almost like Velcro, they stick as they move, due to imperfections in the surfaces of the plates. This creates the tremendous friction that causes crust to melt and become magma, that feeds volcanoes. This friction also causes strain to build at plate boundaries and associated faults, and when the strain reaches beyond the tolerance of the material in the crust, it snaps loose. Denser, more compact crust, mainly granitic in nature, cause higher magnitudes because it has higher inherent resistance to fracture.
To sum up — it seems like there have been more high-magnitude earthquakes of late because we are seeing them at major plate boundaries, as those boundaries release their energy. The Earth is always in motion, and this is the price we pay for living on its surface. That is has remained stable enough to allow humans to evolve to our present state is one of the miracles of the universe.
*nodnod* absolutely. Secondary disasters such as tsunamis may be affected by climate change, but I don't think recent earthquakes have any human-made component to them.
I went googling for some info and found out drilling for gas and oil can cause induced seismicity. A few days ago, drilling was halted in Arkansas because of earthquakes:
"Two oil and gas companies agreed to temporarily shut down wastewater disposal wells in Arkansas that some experts believe are connected to a recent swarm of earthquakes." Waste Wells To Be Closed In Arkansas, Campbell Robertson NewYorkTimes March 4, 2011
Like you said, the big earthquakes along fault lines are to be expected. But I'm wondering if drilling can make them more frequent? Trigger increased intensity? I've only been googling for about 15minutes, but the conspiracy theorist in me is suspicious…