MIT earthquake expert Nafi Toksoz says the clustering of four major earthquakes in land areas this year has been statistically unusual, but the earthquakes are nonetheless unrelated.
The past three months have seen a magnitude 7.4 earthquake in Izmit, Turkey; a magnitude 7.6 earthquake in Taiwan; and a magnitude 7.5 earthquake near Oaxaca, Mexico. Most recently, there was a magnitude 7.0 earthquake in a remote region of the Mojave Desert in southern California on October 16. The last two caused less damage than the Turkey earthquake, which killed 17,000 and left half a million people homeless, and the Taiwan quake, which caused 2,000 deaths and extensive damage.
"The occurrence of four major earthquakes in different parts of the world close to population centers is unusual, but given that these earthquakes occurred in widely separated regions of the world, they are not related," said Dr. Toksoz, professor of earth, atmospheric and planetary sciences.
On average, about a dozen earthquakes of magnitude 7 or greater occur around the globe every year. Most of these are located in the Circum-Pacific belt, offshore and in remote areas. The last time a clustering of earthquakes occurred in land areas was in 1976, when earthquakes in Guatemala, China, Italy and Turkey were responsible for more than 300,000 deaths.
A version of this article appeared in MIT Tech Talk on October 27, 1999.