posted on Aug, 12 2010 @ 05:41 PM
I'm more into earthquakes than lava but ................
I was just reading this article on geology.com about Novarupta volcano eruption in Alaska in 1912.
The largest eruption of material in the 20th century.
What caught my interest is that they say the eruption finished on the 9th July.
There were 3 very strong 7+ quakes within 100miles after that date over the next 5 months, the first four days later according to ANSS.
150km ( 83 miles) to the NE at the end of the volcano chain and the entrance to Cook Inlet
Date/Time: 1912/6/10 16:6:6
Lat: 59 Long: -153
84km (51 miles) in Shelikof Strait
Date/Time: 1912/11/7 7:40:
Lat: 57.5 Long: -155
108km ( 67miles) SSE on Kodiak Island
Date/Time: 1912/12/5 12:27:36
Lat: 57.5 Long: -154
I don't know if I just haven't noticed this before, wasn't paying attention? or is this a common occurance to have big quakes after a big
eruption?. I know that quakes do preceed most eruptions, in many cases Mag 7+ size.
My thoughts are that perhaps because so much volume of magma was withdrawn from the earth during that eruption that these quakes are perhaps related
to the change / re-structure of the crust to compensate for the big hole left behind.
I could be oversimplifying it. It may be quite common.