One of our most reassuring comforts is that when we look out our window at the yard, or take a walk down the street, or go to the beach, or go rock climbing, is that we are interacting with “solid earth.” When things operate “as usual,” it is “solid earth.”
About 1.4 million times each year, the earth shows us that it really is not as solid as it appears. That is the number of earthquakes of at least magnitude 2 on the Richter scale that affect our home planet, according to the USGS (United States Geological Survey). Earthquakes less than magnitude 2 are not normally felt by humans, and are known as microquakes.
Even small quakes, that do little more than wake you up at night or rattle the dishes on the shelves, can be scary events. Large quakes, that cause great property damage and loss of life, are terrifying.
There have been deadly quakes throughout history. Of the ten deadliest recorded quakes in history, all have been in Asia. Of 24 deadliest quakes (those that have caused 50,000 or more deaths), 18 have been in Asia, five have been in Europe, and one in South America. Among the reasons for the seeming over-representation of Asia on the list of deadly quakes are two notable ones: the fact that Asia has a larger population than any other continent, and much of the continent sits at or near tectonic plate boundaries, which are the focus for the majority of earthquakes.
The deadliest quake in history is that of 23 January 1556, centered near Huaxian, Shaanxi (Shensi) Province, China. It is known as the Shaanxi quake, or, in China, the Great Jiajing Earthquake (after the name of the emperor at the time). Based on evidence of destruction, it is thought to have been a magnitude 8 earthquake. At least 830,000 people lost their lives. According to records from the time, “the identified death toll of soldiers and civilians was 830,000, and the unidentified was uncountable.” (1) the quake was felt in all or parts of 9 of the provinces of China at the time. One reason for the huge loss of life was that many thousands of people lived in “yaodongs” (artificial caves) in loess cliffs in the area of the quake, and they collapsed completely.
The next deadliest quake in history was also in China, and occurred at Tangshan, Hebei Province, China on 28 July 1976. It had a magnitude of at least 7.5. The death toll has been variously reported (in large part because the government did not want to admit to the severity of the quake) as anywhere from 240,000 to 655,000, and injured numbers of in the neighborhood of 750,000 (again, varying numbers are cited). There was damage as far away as Beijing, 140 km (87 miles) away.
The Indian Ocean quake of 26 December 2004 was epicentered off Aceh Province, Sumatra, Indonesia, and had a magnitude of approximately 9.3. Dead and missing numbered anywhere from 225,000 to 300,000 as a result of the earthquake and the subsequent tsunami that touched 11 nations around the Indian Ocean. A further 1,700,000 people lost their homes. More than $7 billion in humanitarian aid was sent to the affected nations.
11 October 1138 was the date of the Aleppo (Syria) earthquake that is estimated at a magnitude 8.5. The death toll of 230,000 was first reported in historical writings from the 15th century, and may have included statistics from other earthquakes in the same general time period.
There were three other earthquakes that had death tolls estimated at 200,000:
Damghan, Iran, on 22 December 856. Little information is available on this quake.
Haiyuan County, Ningxia (then Gansu) Province, China on 16 December 1920. This earthquake had a magnitude of 7.8 (or, according to Chinese sources, 8.5), and caused damage in 7 provinces. The Ningxia Daily has given figures of 240,000 deaths, while the USGS uses a figure of 200,000.
The final 200,000-range earthquake was also a Chinese quake. It was the 22 May 1927 quake of Xining, Xinghai, China, with a magnitude of 7.8.
Our home is very active, constantly in motion. This bring many natural disasters along with all the natural beauty and bounty.
(1)http://earthquake.usgs.gov/regional/world/most_destructive.php
http://geography.about.com/b/2006/09/06/number-of-earthquakes-per-magnitude-each-year-worldwide.htm
http://www.infoplease.com/ipa/A0884804.html
http://en.wikipedia.org/wiki/List_of_earthquakes
http://www.cbc.ca/news/background/forcesofnature/earthquakes.html
