Earthquake Frequency has not Increased in 2010
Planet Earth certainly seems to be experiencing a large number of strong earthquakes recently. All of this destruction has people asking whether there has been an increase in the number of earthquakes within the last several years. The answer is actually no, there has NOT been an increase in the number of earthquakes of any magnitude in the last decade, when compared to records kept since 1900.
According to the US Geological Survey, the earth has experienced, on average, 16 earthquakes of magnitude 7.0 and greater each year, 15 in the 7.0 – 7.9 range, and 1 of magnitude >8.0.
So far in 2010 we have seen 6 major earthquakes, one of >8.0 (Chile 02.27.10) and 5 in the 7.0-7.9 category (Solomon Islands 01.03.10 M7.1; Haiti 01.12.10 M7.0; Ryukyu Islands, Japan 02.26.10 M7.0; Baja California, Mexico 04.04.10 M7.2; and Sumatra Indonesia 04.06.10 M 7.7).
While large earthquakes are certainly rare and newsworthy, the earthquake in southern China on Wednesday (M6.9) shows that even earthquakes in the magnitude 6.0-6.9 range can be very destructive. Unfortunately, the earth experiences and average of 134 such earthquakes each year. So far in 2010 we have experienced 59, well within the average. Some of these were aftershocks of the major earthquakes of 2010. Others were independent events, including the Qinghai Province earthquake, a M6.3 in Spain earlier this month, and the M6.1 earthquake in Eastern Turkey in March.
Number of Earthquakes Worldwide for 2003 – 2010
Located by the US Geological Survey National Earthquake Information Center
Click the link to see the full table (2000-2010) on the USGS site
|8.0 to 9.9||1||2||1||2||4||0||1||1|
|7.0 to 7.9||14||14||10||9||14||12||16||5|
|6.0 to 6.9||140||141||140||142||178||168||142||59|
|5.0 to 5.9||1203||1515||1693||1712||2074||1768||1725||717|
|4.0 to 4.9||8462||10888||13917||12838||12078||12291||6956||2413|
|3.0 to 3.9||7624||7932||9191||9990||9889||11735||2897||489|
|2.0 to 2.9||7727||6316||4636||4027||3597||3860||3007||697|
|1.0 to 1.9||2506||1344||26||18||42||21||26||7|
|0.1 to 0.9||134||103||0||2||2||0||1||0|
* Starting in January 2009, the USGS National Earthquake Information Center no longer locates earthquakes smaller than magnitude 4.5 outside the United States, unless we receive specific information that the earthquake was felt or caused damage.
Why does it seem like we are having more major earthquakes when we are really not?
1) Impact of human tragedy – as the world’s population increases, the number of people living in earthquake prone areas also increases. The earthquakes in 2010 have not been more powerful or more frequent than in past years, but they have occurred more often near populated areas. Often those areas were not well prepared for a major earthquake (Haiti, southern China). This has dramatically increased the number of casualties, injuries and homelessness from earthquakes compared to the past 10 years, as you can see from the last row of the chart above. The exception to this is 2004. The casualty figures for that year include the 227,898 people killed or missing/presumed killed in the terrible southeast Asian tsunami caused by a M9.1 earthquake off the coast of Sumatra.
2) Improved global communication – the world feels smaller and smaller every day as more and more people are connected by satellite, telephone and the Internet. News travels faster and farther today than in the past, and so we are more likely to get extensive news coverage of destructive earthquakes in other parts of the world.
3) Improved ability to detect earthquakes – there are now 4000 seismology stations detecting earthquake activity worldwide, more than at any time in history. This increased monitoring increased the speed and accuracy of earthquake detection, allowing reliable reports to reach the public in near-real time instead of days or weeks later. This means that even earthquakes in remote parts of the world are detected and reported to the public.
Post updated 12.30.10 to correct for 2009 and 2010 being cut off the table by my new theme’s page width formatting. The full table with information on earthquakes in 2000, 2001 and 2002 is available on the USGS website.