Very interesting fact I never knew!
http://www.accuweather.com/blogs/news/story/45653/earthquake-nofrost-quake.asp
Makes sense to me. Ive often pondered the various thermal effects on the earth. Also global warming, of the air and ocean, will warm and expand the crust, causing stress which will need to be relieved. ie: Earthquakes. further stress is caused by deep wells pumping water, or oil and gas from the ground. we get settling of the earth, and movement. there are lots of things we do without thinking, and are then surprised by the consequences.