The number of major earthquakes for 1999 was above normal, and quake-related casualties were double the annual average, according to premilimary figures issued in early January by the U.S. Geological Survey (USGS).
Earthquakes caused more than 22,000 deaths worldwide in 1999. More than 17,000 people were killed as a result of the magnitude 7.4 Izmit, Turkey, earthquake on Aug. 17.
“Dense urban populations coupled with weak building structures along the epicenters are responsible for most fatalities,” said Waverly Person, geophysicist with the USGS National Earthquake Information Center in Golden, Colo.
The annual, long-term average is 10,000 deaths worldwide. In 1998, fatalities totaled 8,928, while 2,907 people were killed in 1997. The deadliest year in this century was 1976 when at least 255,000 people, and perhaps more than 600,000, were killed after one quake rocked Tianjin (formerly Tangshan), China.
“Overall, earthquake activity isn’t on the rise,” said Person. “We’re simply able to locate more lower magnitude earthquakes due to advances in the technology.”
A typical year for earthquakes consists of 18 major temblors (magnitude 7.0 to 7.9) and one great quake (8.0 or higher), according to the USGS. In 1999, no great quakes occurred, but 20 major earthquakes shook the globe. This figure is far below the 41 major and great earthquakes recorded in 1943.
Colombia felt the fatal effects early in 1999 when a magnitude 6.3 killed nearly 1,200 people on January 25. Turkey was the hardest hit, sustaining two major quakes — the Aug. 17 magnitude 7.4 and a magnitude 7.1 on Nov. 12. Taiwan suffered the year’s largest event, a magnitude 7.6 quake on Sept. 20 that killed more than 2,400 people.
The USGS estimates that several million earthquakes occur in the world each year. Many go undetected because they hit remote areas or have very small magnitudes. The agency now locates about 50 earthquakes each day, totaling 20,000 a year.