Do the earthquakes going on now mean something is going on with the earth's crust?
May 10, 2010
in
Earthquake Questions
Okay, there have been a lot of earthquakes recently: a small on in Chicago, the one in Haiti, one in Chile, one in Mexico and one near Tibet, and now there’s volcanic activity in Iceland, which is basically a little chunk of land on a fault line. All of the earthquakes except for the 2.5 one in
Chicago have been above 7.0 in magnitude. Does this mean something’s going on with the earth’s crust?
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3 comments
Aj on May 10, 2010 at 5:16 am
The number and intensity of earthquakes is not increasing. Our ability to detect them is greatly increasing. They are also being reported by the news media more rapidly and covered more widely.
Earthquakes of the magnitude of the Haiti and Chile quakes happen on the average 2 to 3 times per year. It is just coincidence that these two occurred closely together. Disaster makes more exciting news than "Everything was calm and quiet today."
"The USGS estimates that several million earthquakes occur in the world each year. Many go undetected because they hit remote areas or have very small magnitudes. The NEIC now locates about 50 earthquakes each day, or about 20,000 a year.
As more and more seismographs are installed in the world, more earthquakes can be and have been located. However, the number of large earthquakes (magnitude 6.0 and greater) has stayed relatively constant.
A partial explanation may lie in the fact that in the last twenty years, we have definitely had an increase in the number of earthquakes we have been able to locate each year. This is because of the tremendous increase in the number of seismograph stations in the world and the many improvements in global communications. In 1931, there were about 350 stations operating in the world; today, there are more than 8,000 stations and the data now comes in rapidly from these stations by electronic mail, internet and satellite. This increase in the number of stations and the more timely receipt of data has allowed us and other seismological centers to locate earthquakes more rapidly and to locate many small earthquakes which were undetected in earlier years. The NEIC now locates about 20,000 earthquakes each year or approximately 50 per day. Also, because of the improvements in communications and the increased interest in the environment and natural disasters, the public now learns about more earthquakes.
According to long-term records (since about 1900), we expect about 17 major earthquakes (7.0 – 7.9) and one great earthquake (8.0 or above) in any given year."
Soilguy on May 10, 2010 at 5:16 am
Yes, it means that the crust is acting as it normally does.
The apparent increase in earthquakes that you’re noticing is because you are made more aware of them. The ones in Haiti and Chile were especially easy for the US media to cover.
See the link. The number of earthquakes we’ve had recently is in line with historical earthquake frequency.
Geology Rock Star on May 10, 2010 at 5:16 am
Yes. Heat is escaping from the earth’s interior causing convection currents within the the earth’s mantle. These convection currents cause the crust to split into different plates and move across the earth’s surface. These earthquakes are indeed, normal. It might seem unusual, but that’s only because the media is doing a better job of reporting them. that is all.