Quakes Pack More Punch in Eastern Than in Central United States

[rangerrebew]

 Quakes Pack More Punch in Eastern Than in Central United States

A new finding rests on the recognition that fault types differ between the two regions. It helps explain prior evidence that human-induced quakes and natural ones behave the same in the nation’s center.
 

By Kimberly M. S. Cartier 18 August 2017

Earthquakes in the eastern United States and Canada are many times more severe than central U.S. earthquakes of human or natural origin, earthquake scientists have found, highlighting a crucial need to separate the two regions when designing future earthquake hazard maps. The study separated the regions from the Mississippi-Alabama border up to the base of Lake Michigan, approximately 87°W.

https://eos.org/articles/quakes-pack-more-punch-in-eastern-than-in-central-united-states

[IsailedawayfromFR]

Quakes Pack More Punch in Eastern Than in Central United States

A new finding rests on the recognition that fault types differ between the two regions. It helps explain prior evidence that human-induced quakes and natural ones behave the same in the nation’s center.
 

By Kimberly M. S. Cartier 18 August 2017

Earthquakes in the eastern United States and Canada are many times more severe than central U.S. earthquakes of human or natural origin, earthquake scientists have found, highlighting a crucial need to separate the two regions when designing future earthquake hazard maps. The study separated the regions from the Mississippi-Alabama border up to the base of Lake Michigan, approximately 87°W.

https://eos.org/articles/quakes-pack-more-punch-in-eastern-than-in-central-united-states

@Smokin Joe - maybe due to harder, more dense rock in the east, and a relatively soft middle?

[Smokin Joe]

@Smokin Joe - maybe due to harder, more dense rock in the east, and a relatively soft middle?

Pretty much. The crystalline basement rocks (Igneous and metamorphic) are closer to the surface in the East as a rule than they are in the middle, where thicker sedimentary rocks overlay those crystalline rocks. That may well be the mechanism that dampens the effects in the middle of the craton.

The map shows the older rocks of the east in contrast to the coastal sediments of the Gulf region and those of the Western US.

[Mad Max]

Pretty much. The crystalline basement rocks (Igneous and metamorphic) are closer to the surface in the East as a rule than they are in the middle, where thicker sedimentary rocks overlay those crystalline rocks. That may well be the mechanism that dampens the effects in the middle of the craton.