Chile Will Study San Francisco Quake

Scientists and engineers in Chile, which has the distinction of playing host to the largest earthquake ever measured, are waiting with serious interest reports on the Oct. 17 San Francisco earthquake.

Measured by magnitude, “Chile is the world’s most seismic country,” said building engineer Elias Arze, president of the Chilean Seismology and Anti-Seismic Engineering Assn.

The San Francisco quake measuring 7.1 was comparable to the earthquake that struck Santiago and central Chile in March, 1985, killing 180 people and toppling some 70,000 homes.

And like California, Chile is still waiting for another “big one,” an earthquake of magnitude 8 or more. Both areas are situated along the Pacific “ring of fire,” the huge faults created by the collision of massive plates of the earth’s surface.

“Chile, along with Alaska, are the sites that have had the biggest seismic occurrences,” said Prof. Edgar Kausel, chairman of the Geophysics Department at the University of Chile.

Chile has about 2,270 miles of its coast along the earthquake fault between the Nazca plate and the South American plate. The frequency of earth movements prompts Chileans to say that every president has at least one major earthquake during the traditional six-year term in office.

The long history of earth movements in Chile has led to a sharing of information with U.S. and Japanese scientists and engineers over the behavior of the earth and of buildings during earthquakes.

Arze said after the 1985 earthquake, teams of foreign experts arrived in Chile to study the effects of the earthquake on buildings.

“Our buildings performed very well,” he said.

Since earthquake building codes were implemented in Chile in the 1930s, only two engineered buildings have collapsed, he said. Older buildings have been replaced over the years.

“We have so many earthquakes in Chile it has cleaned up our construction,” Arze said.

Chilean earthquakes tend to be sharper and last longer than those of California, leading to differences in building design.

While California engineers have promoted a flexible design of steel framed buildings that allows them to swing in a quake, Chileans opt for stiffer construction. Chilean buildings are of reinforced concrete with more inside walls.

“Our buildings move little compared to (those of) the Americans,” said Arze.

Descriptions of earthquakes in Chile date back to Spanish settlers in 1575.

In an 1835 journal entry about a stop the ship the Beagle made in Chile, scientist Charles Darwin described an earthquake he experienced.

Just a few months before the 1906 earthquake in San Francisco, a quake measuring 8.5 struck the central Chilean coast, destroying the city of Valparaiso.

On May 21, 1960, an earthquake measuring 9.5 struck an area about 600 miles long in southern Chile, releasing energy nearly 1,000 times that of this year’s San Francisco quake. Parts of the coast stretching south from the city of Concepcion, 325 miles south of Santiago, dropped nine feet.

“It was the biggest registered in the history of seismic instrumention,” said Kausel.

About 5,000 people were killed in the sparsely populated area, most of them when the coastline dropped. A tsunami, a tidal wave created by the earthquake, killed others and caused considerable damage in Japan and Hawaii.