MadSci Network: Earth Sciences

Re: Is there any correlation between global warming and increases in Geological

Date: Sun Nov 13 23:09:05 2005
Posted By: David Dunbar, Staff, Geophysics, GeoCenter, Inc.
Area of science: Earth Sciences
ID: 1131636046.Es


Interesting question. Heat from global warming would have to penetrate
several kilometers into the Earth to affect the earthquake frequency. Rock
is actually a fairly good insulator so it would take hundreds to thousands
of years for heat to penetrate deep enough to reach the focal depth of
earthquakes.  Earthquakes occur as deep as 800 km, but most are much closer
to the surface.

The sources of volcanoes are also fairly deep, on the order of 20 to 60 km.
A change in the surface temperature would take thousands of years to
penetrate that far. 

A question that comes up fairly often is is the frequency of earthquakes
increasing. The answer is no. What has increased is the ability to record
and locate smaller earthquakes. Earthquakes of magnitude of 6.5 and above
have generally been well located anywhere in the world since at least 1900.
The number of these earthquakes has been fairly steady at roughly 152 per
year on average. In 1963 the World Wide Seismic Standard Seismograph
Network came on line. The number of well located earthquakes of magnitude
4.5 and above jumped. This was not an increase in the frequency of
earthquakes, it was an increase in the ability to detect them. Also reports
of distant disasters have been covered more in the news media.


A couple of web sites that may be of interest are:

National Earthquake Information Center

A paper by 
V. G. Kossobokov


Current Queue | Current Queue for Earth Sciences | Earth Sciences archives

Try the links in the MadSci Library for more information on Earth Sciences.

MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci

MadSci Network,
© 1995-2005. All rights reserved.