This year has seen major quakes in Haiti, Chile, Mexico, and now China. However, while this succession of major, devastating quakes could be seen as unusual, there is little reason to believe that frequency of major earthquakes has increased significantly since the network of seismographs was established.
Photo by photos. com.
According to the United States Geological Survey, the annual number of earthquakes worldwide having a magnitude of M6.0-M6.9 is 134. For quakes M7.0-M7.9, the number lowers to 17. For great quakes of M8.0 or greater, the number is near 1.
The estimates for M6.0-M6.9 temblors are based upon data since 1990. Otherwise, the dates reflect observations since 1900.
Image Credit: USGS
For quakes above M7.0, there has been no important annual rise in frequency since 1900, according to the USGS. But reporting of quakes of M6.0-M6.9 seems to have risen perceptibly. That lesser earthquakes are reported with increasing frequency since the establishment of a seismic network likely owes to the continuing proliferation of seismic stations around the Earth.
Another important thing to consider is that the timing between natural events such as earthquakes tends to be uneven, with flurries of activity followed by relative breaks. This owes to the randomness that is inherent in natural phenomena.
Then, too, there is the matter of perception. A quick succession of major earthquakes can make headlines and become embedded in memory, but the spells of relative quiet are rarely, if ever, borne in mind.
Story by AccuWeather.com Senior Forecaster Jim Andrews.
Two children were killed and at least another 15 people were injured Monday evening, as strong storms forced a circus tent to collapse in Lancaster, New Hampshire.
A fall-like cooldown is in store through the end of the week for the Northeast.
Unsettled weather responsible for flooding downpours in Florida last week will gradually lessen over the next several days.
Tropical Storm Guillermo will continue its path toward Hawaii in the coming days bringing large swells and enhanced rainfall to the islands.
After a very hot end to July, some relief is on the way this week for Seattle and other areas of the Northwest.
Building heat across Europe this week will approach monthly and all-time record high levels in several cities.
Louisville, KY (2009)
4.52 inches of rain fell, breaking the old daily record of 1.72 inches set in 1938.
Erie, PA (1915)
Flood killed 75 people, many streets flooded, bridges torn out.
Ossian, IA (1979)
Strong winds from a thunderstorm damaged a roller rink roof 50 miles NE of Waterloo, IA. A barn was destroyed and trees and power lines were downed.