The National Aeronautics and Space Administration (NASA) has provided us with some interesting observations about why the February 2011 earthquake in the Christchurch, New Zealand area did so much more damage that the one that occurred in September 2010. Check out their satellite image showing the varying severity levels of the quake as well as their explanation about how time of day and location are often even more powerful factors in resulting damage than the severity on the Richter scale–visit http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=49586&src=eorss-nh. Note that in addition to the shaking and movement of the earth, in these quakes, there is also “liquefaction” of the soil when groundwater and earth are forced together, which creates yet another kind of impact on the surrounding areas.
Archive for the ‘Earthquakes’ Category
The University of Canterbury Library remains closed following the earthquake that struck Christchurch, New Zealand, on February 22nd. Their electronic resources are still available and they have set up a special Earthquake Recovery page, which you can see by clicking on the following URL: http://wiki.canterbury.ac.nz/display/LIBRARY/Earthquake+Recovery+At+UC+Library.
Just after 11pm on February 27th, a 4.7-magnitude earthquake struck central Arkansas, serving as a reminder that earthquakes can happen east of the Rockies. Below is a magnitude scale chart that I found at a Michigan Tech site (http://www.geo.mtu.edu/UPSeis/magnitude.html). You can use the chart to see the difference between the Arkansas earthquake and the 6.3-magnitude earthquake that hit Christchurch, New Zealand last week. (A 7.1-magnitude earthquake also struck Christchurch on September 4th.) When was the last earthquake in your state? To find out, click on the following URL from the United States Geological Society: http://earthquake.usgs.gov/earthquakes/eqarchives/last_event/states/.
|Magnitude||Earthquake Effects||Estimated Number
|2.5 or less||Usually not felt, but can be recorded by seismograph.||900,000|
|2.5 to 5.4||Often felt, but only causes minor damage.||30,000|
|5.5 to 6.0||Slight damage to buildings and other structures.||500|
|6.1 to 6.9||May cause a lot of damage in very populated areas.||100|
|7.0 to 7.9||Major earthquake. Serious damage.||20|
|8.0 or greater||Great earthquake. Can totally destroy communities near the epicenter.||One every 5 to 10 years|
We have been following events in Christchurch, New Zealand, since a 7.1 magnitude earthquake hit the city back on September 4th. The library at the University of Canterbury was damaged by the quake and was scheduled to re-open this month. Sadly, a 6.3 magnitude earthquake struck the city yesterday and there are fatalities. Here’s a link to an article about the earthquake from the Christian Science Monitor: http://www.csmonitor.com/World/Asia-Pacific/2011/0222/New-Zealand-earthquake-Authorities-scramble-after-temblor-leaves-at-least-65-dead. You can also follow news reports and personal accounts on Twitter by searching #christchurch.