High rises unaffected by quakes: BMG

Mustaqim Adamrah and Adianto P. Simamora, The Jakarta Post, Jakarta

The Meteorology and Geophysics Agency (BMG) said Thursday the earthquake and aftershocks that rattled western Sumatra on Wednesday would not affect buildings in the capital.

"All buildings and infrastructure in Jakarta have been designed to adapt to quakes," earthquake division head Suhardjono said at the agency's headquarters.

The epicenter of Wednesday's 7.9-Richter-scale earthquake was some 100 kilometers southwest of the capital of Bengkulu and at a depth of about 15 kilometers.

Bystanders on Jl. Jend. Sudirman, Central Jakarta, reportedly saw office buildings sway during the quake.

The Jakarta disaster coordinating task force head, Bobby Aryono, said the unit had not received any reports of damaged buildings as of Thursday afternoon.

Suhardjono said the buildings and infrastructure were designed to sway according to the movement created by an earthquake and thus were safe from it.

"So, Jakartans should not have panicked or been hysterical. Moreover, the epicenter was far (from the capital). It would have been another story if the epicenter were nearby," he said.

However, geotechnical engineering researcher at the Indonesian Institute of Sciences Adrin Tohari said that Jakarta's northern coastal area was vulnerable to liquefaction during earthquakes as it sat on unsolid soil.

Liquefaction makes the ground lose its ability to support structures.

"It would ruin buildings and blow up pipelines planted below the surface. The reclamation areas on the northern coastline are prone to liquefaction," he told The Jakarta Post on Thursday.

Adrin made the prediction based on his research on the impact of an earthquake on liquefaction risks in Bengkulu.

The research, carried out in July, found that an earthquake measuring 7.3 on the Richter scale that hit Bengkulu in 2000 caused land subsidence of between 20 centimeters to 30 cm in coastal areas.

"The composition of Bengkulu's coastal areas is mostly cohesion-less sands and clay similar to Jakarta's northern coastal zone," he said.

Houses in coastal areas of Bengkulu collapsed in the 2000 earthquake.

The Jakarta administration is reclaiming a 32-kilometer stretch of northern coastline to add about 2,700 hectares of land to the city.

The land will be used for industrial parks, hotels, office buildings and upscale accommodation for up to 1.19 million residents.

The BMG recorded three aftershocks in Sumatra on Wednesday and Thursday and issued a tsunami warning.

Suhardjono said that the quake and its aftershocks resulted from clashes and friction between the Indo-Australian tectonic plate and the Eurasian tectonic plate.