City buildings designed for worse quakes: Experts

JAKARTA (JP): High rise buildings in Jakarta were designed to withstand earthquakes of much greater intensity than Monday's tremors, experts here said.

The intensity would have to be at least two and a half times that of Monday to damage buildings, architect and building consultant Wiratman Wangsadinata said yesterday.

"For a building to be on the verge of collapse the intensity of a quake would have to be 15 times that of yesterday," the owner of Wiratman and Associates said.

Fathur Rachman of the Indonesian Association of Architects said buildings here were designed to withstand quakes up to 7 on the Richter scale. Monday's quake at 3:05 p.m. measured 6.0 on the Richter scale. Its epicenter was 300 kilometers southwest of here and 33 kilometers under the Indian Ocean.

Cracks caused by the quake would mean there were faults in either planning or construction, Wiratman said.

"All buildings with cracks should be thoroughly inspected," he said. "But slight cracks are not a source of worry," he added.

Public works officials checked several high rise buildings yesterday but their investigation results are not yet available.

A hotel on Jl. Jend. Sudirman, a bank building in Central Jakarta and the third floor of a building's parking lot were among those reported to have cracks.

The hotel's maintenance employee said the cracks on the walls of several floors would be repaired soon and the floors were open as usual.

A source at the bank said there was a five to six-centimeter crack on the outside wall, and ceilings from the second to fifth floor were cracked.

"A piece of concrete as big as a typewriter fell to the second floor," the building's security guard said. The fall caused severe damage to part of the ceiling and the aluminum door frame, he said.

The building management were unavailable for comment.

The earthquake caused panic across Jakarta and in West Java. Thousands spilled out of high rise buildings, fighting their way down emergency stairs.

Wiratman said the intensity of Monday's quake recorded at V Modified Mercalli Intensity in Jakarta was a two percent acceleration in gravity (G).

"Rules on building design in Jakarta are anticipated to withstand five percent of G, meaning a building should stand unharmed in a quake more than double that of yesterday," he said.

A building would collapse if a quake was 30 percent G, or 15 times that of Monday's intensity, Wiratman said.

The standards anticipate a 10 percent probability of a building's collapse in 50 years, the average age of a building, he added.

The public order office also reported cracks on an apartment wall in Central Jakarta and that a car window was smashed near the Sarinah department store on Jl. M.H. Thamrin, by a piece of falling marble.

A National Science Institute employee was slightly injured when he fell out of the building after smashing a window of the first floor, the report said.

Wiratman added it was useless trying to flee in a quake.

"If a strong quake lasts for 20 seconds the building could collapse in 20 seconds," he said. People should immediately seek safety under furniture, and only go out when tremors have subsided. (anr/04/ste)