Earthquakes in the US: Alaska
Alaska’s earthquakes in the week of 19-25 June 2013. Image credit: USGS
Some describe Alaska as the India of North America – a large piece of continental crust driving against an even larger continent. In fact the northwards movement of the Pacific plate has carried a number of slivers of crust – microplates- against the stable North American plate over millions of years.
This motion, as well as raising the mountains of the Alaska and Brooks ranges and generating the volcanic arc of the Aleutian Islands, generates earthquakes along the length of the collision zone and, where continental crust and continental crust collide, further inland.
Quakes and Predictions
Seismologist Roger Musson, in his book The Million Death Quake, muses on the science of earthquake prediction, how ‘easy’ it is, how his prediction of a tremor of at least M4 in the Pacific in a given week is guaranteed. “I could be even be even more specific and still have a huge chance of success – magnitude greater than 6, Pacific Region, next week.”
This week, Dr Musson’s prediction might not have been fulfilled – but the lack of large earthquakes in the Pacific and the occurrence of a large tremor in the Atlantic go to demonstrate not just the variability of earthquakes but also the range of settings in which they occur.
Sources
Musson, R. The Million Death Quake. (2012). Macmillan.
Okal, E.A. and Stein, S. The 1942 Southwest Indian Ocean Ridge Earthquake: Largest Ever Recorded on an Ocean Transform Fault.(1987). Geophysical Research Letters. Accessed 25 June, 2013
USGS. Real time earthquake map. (2013). Accessed 25 June 2013
Yeats, R. Active Faults of the World. (2013). Cambridge University Press.
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