Replies

Thrust faulting in the 21st Century

an ‘Olympic’ and then some event..

Time has this..

—

The Ring of Fire: Why Chile’s Quake Wasn’t Unexpected

http://news.yahoo.com/s/time/20100227/wl_time/08599196852700

Scientists still can’t predict exactly when earthquakes will occur, but the massive temblor that struck off the coast of Chile early Saturday was anything but unexpected. Chile sits on the Ring of Fire, the volatile, 40,000 km-long (25,000 MILE) zone that encircles the Pacific Ocean and includes the most seismically dangerous ground on the planet. The unstable plate tectonics along the Ring produce some 90% of the world’s earthquakes as well as most of its volcanic eruptions. (See where experts predict the next five major earthquakes will be.)

Because the Ring follows the coastlines of Pacific Ocean, almost any major quake can also produce a tsunami, a powerful wave that travels from the epicenter of the temblor across the ocean basin. That’s what happened in 2004, when a 9.3-magnitude quake off the Indonesian island of Sumatra triggered a devastating tsunami, and that’s is what’s likely to happen following today’s 8.8-magnitude quake off the coast of Chile. (See the latest photos of the earthquake in Chile.)

Temblors in the Ring of Fire are so common that a 7.0-magntitude quake hit Japan’s Ryuku Islands yesterday. Today’s Chilean quake occurred on one of the more powerful fault lines in the region, where the underwater Nazca Plate in the Pacific gradually submerges beneath the westward moving South American plate. The border between these two plates is known as a thrust fault, and the sudden rubbing of the plates against each other resulted in an earthquake that ripped across an estimated 400 miles of the fault. With a Richter scale magnitude of 8.8, the Chilean quake was nearly 1,000 times stronger than the temblor that hit Haiti last month.

Chile, however, is no stranger to major earthquakes. In 1960, a 9.5-magnitude temblor - the strongest quake ever recorded by scientific instruments - hit the Chilean city of Valdivia, killing nearly 2,000 people. And although today’s quake is the strongest in the last half-century to hit Chile, the country has had 13 quakes of 7.0 or higher on the Richter scale since 1973. That geologic history helps explain why building codes are far tougher in Chile than they are in Haiti, which should help limit the number of casualties from today’s quake. ..