GUAM EARTHQUAKE AFTERSHOCKS RECORDED

admin's picture

By Theresa Merto

HAGÅTÑA, Guam (April 30, 2002 – Pacific Daily News)---More aftershocks are expected to sway the island as a result of Saturday morning's earthquake, but there is no way to accurately forecast temblors.

"We have not gotten to the point where the information is reliable and accurate," said Paul Hattori, a geophysicist with the U.S. Geological Survey station on Guam.

"I was not even expecting this earthquake."

The 7.2-magnitude temblor, which caused an island wide power outage, damaged buildings and broke water pipes, shook residents out of bed at 2:06 a.m. Saturday.

As officials continue to assess damage, Hattori said more than 100 aftershocks have hit Guam since the weekend temblor, and a few more with magnitudes from 4.0 to 6.0 are expected. Since the quake, there have been at least four temblors with a magnitude of at least 4.0, while the other quakes were minor, he said.

The epicenter of Saturday's quake was 30 miles southwest of Hagåtña and 47.5 miles deep, according to a U.S. Geological Survey report from Civil Defense. The quake lasted less than a minute, but some residents may have felt the earth move longer if they were closer to the epicenter.

The quake eclipsed the 7.0-magnitude temblor that shook Guam Oct. 13 and was the strongest to hit the island since the 7.5-magnitude temblor in August 1993.

Hattori said Saturday's quake was related to both of those quakes.

He also said that Saturday's temblor may be the continuation of the October quake.

"Possibly, the October 2001 was never completed," he said. "It is not common, but it is not unheard of."

Hattori said Guam does not experience as much damage from quakes as the U.S. mainland and other countries because most of the island is not on sedimentary soil, and because structures here are built strong enough to sustain typhoons and major temblors.

'Ring of fire'

An earthquake is caused by a sudden slip on a fault, according to the U.S. Geological Survey Web site, http://www.earthquake.usgs.gov. Stresses in the earth's outer layer push the sides of the fault together. Stress builds up and the rock slips suddenly, releasing energy in waves that travel through the earth's crust and cause the shaking felt during an earthquake. An earthquake occurs when plates grind and scrape against each other.

Guam is susceptible to more quakes, in part, because of the "ring of fire," Hattori said.

Volcanic arcs and oceanic trenches partly encircling the Pacific Basin form the ring -- a zone of frequent earthquakes and volcanic eruptions.

Guam is located in the Pacific ''ring of fire,'' where earthquakes and volcanic activity are common.

History

Hattori said though it is difficult to forecast quakes, the island may experience another major temblor if history repeats itself -- but not any time soon.

A handful of highly destructive quakes have hit Guam.

In 1849, a quake of similar strength to the August 1993 temblor hit the island. Hattori said at least one person died from that quake, which generated a tsunami in Umatac Bay and caused flooding in Agat, Inarajan and Pago Bay.

On Sept. 22, 1902, another major quake shook the island. A newly built tower at the Dulce Nombre de Maria Cathedral- Basilica collapsed after the 8.1 magnitude earthquake, according to Pacific Daily News files.

On Dec. 10, 1909, a quake damaged homes and several caused fissures to open in the ground and riverbeds to sink in several places, files state.

"If history is an indication, we will have an earthquake stronger than August 1993, but that is sometime off in the future," Hattori said.

"Hopefully, that will occur in 200- or 300-year cycles."

 

FULL GUAM EARTHQUAKE DAMAGE ASSESSMENT MAY TAKE SEVERAL WEEKS

By Theresa Merto

HAGÅTÑA, Guam (April 30, 2002 – Pacific Daily News)---It may be several weeks before officials complete damage assessments and tally the cost of Saturday's 7.2-magnitude earthquake.

Government officials and structural engineers continue to assess quake damage, said Leo Espia, Guam's Office of Civil Defense earthquake and typhoon program manager.

Espia said officials yesterday looked over damage at P.C. Lujan Elementary School, which sustained structural damage.

"That is the main concern right now," Espia said.

Four classrooms were closed temporarily and the students have been moved to different rooms.

Several government agencies reported only minor structural damage, including small cracks in buildings.

"We are fortunate that we did not have any major damage," Espia said. He said residents also are encouraged to report any structural damage to their village mayors for safety reasons.

For additional reports from the Pacific Daily News, go to PACIFIC ISLANDS REPORT News/Information Links: Newspapers/Pacific Daily News (Guam).

Rate this article: 
No votes yet

Add new comment