Sun, 13 Aug 2000

Indonesia world's most earthquake-prone country

By William Furney

JAKARTA (JP): Every day, some 20 earthquakes rock various parts of Indonesia, leading to a total of about 7,000 subterranean movements each year. Of that number, only about 60 are felt. Among those, however, are what are known as killer quakes -- earthquakes whose magnitude is great enough to destroy buildings, roads and lives.

Such was the case on June 4 this year when a quake measuring 7.3 on the Richter scale flattened much of the town of Bengkulu in the southwestern tip of Sumatra island.

The unrelenting forces of nature are harsh in this tropical country, with lives persistently being ruined by natural disasters such as volcanoes, mudslides and earthquakes, Indonesia having more of the latter than any other country on earth. The Bengkulu quake killed 90 people, seriously injured 803 and left another 1,782 others slightly injured. The quake damaged 30,374 houses, 513 places of worship and destroyed roads in 26 locations. Prosaic though they may be, powerful large-magnitude earthquakes are not something that can be foreseen and when they occur they do so with little regard for human life.

Sri Diharto is used to being woken in the early hours of the morning. After four years as head of the Meteorological and Geophysics Agency (BMG) of the Department of Communications, he is adept at fielding enquiries from jittery journalists. "They want to know everything at once, where the epicenter was and the scale of the quake. They should be more patient," he said in an interview with The Jakarta Post.

But the frustrations of waiting journalists as they edge toward their deadlines and those of his own office are now the stuff of yesteryear, belonging in a small room in the agency's office that houses ancient seismographs from the Dutch era. For, it now has enough leading edge imported technology to make the mouths of the most ardent earthquake trackers salivate. A "Supercomputer Room", chilled by strong air-conditioners awaits the arrival "soon", through a soft loan, of an estimated US$19.5 million terabyte cruncher.

Vice President Megawati Soekarnoputri was due to open the newly renovated facility last month, but due to ongoing political snafus, the opening has been postponed until later in the month.

The new facility encompasses BMG's Communications and Computer Center, Weather and Climate Center, National Earthquake Center and the agency's Air Quality Center.

Operating 24 hours a day and with a total workforce of 3,500, 750 of whom are based at the Jakarta headquarters, BMG is responsible for disseminating information about earthquakes when they occur. Not only to the public and media, but also the National Disaster Management Coordination Board and related government departments so they can send relief or rescue teams.

Said Sri Diharto: "When a quake happens we need at least 15 minutes to determine where the epicenter was. But then we have people on the phone wanting immediate answers and we have to make an estimation. Sometimes, the estimations are wrong, as with the Sukabumi quake. We said the epicenter was in Pandeglang, when later we determined that it had been in Sukabumi."


Even with its new and sophisticated technology, BMG, like other agencies around the world, cannot predict when a quake will occur. But there are certain areas in the country that are more prone than others. West Sumatra, along the Indian Ocean down to the Sunda Strait; the south of West Java around the Sukabumi area which is traversed by the Cimandiri fault; the Nusa Tenggara area; the Maluku islands; and Sulawesi are earthquake hot zones. Also Irian Jaya, which has many local faults and is very prone to earthquakes. The Indoaustralia plate meets with the Euroasia and Pacific plates, and their movements cause intense tectonic activity in Indonesia. Because of the pressure, the Indoaustralia plate moves 7 cm to 12 cm per year. Along of the coast of Sumatra is the most earthquake-prone area, while Kalimantan is virtually quake-free.

Earthquakes are caused by tectonic movements, the shifting of plates in the Earth's crust. If a quake happens on land, like the recent 5.1 magnitude Sukabumi quake, it will be felt and the effects are often devastating. But if an earthquake happens on the sea floor, even with those of large magnitude, the effects are limited and in many cases tremors will not be noticed. The danger of earthquakes under the sea, however, is that they are often followed by tsunami, giant waves caused by the submarine earth movements.

Earthquakes are measured on the Richter scale, which determines the magnitude at the center of a quake while the Modified Mercalli Indicator is what is felt, depending on the distance from the epicenter.

The Bengkulu quake was the most severe over the past few years. The last high-scale earthquake in Bengkulu was in 1833, and there were resulting tsunami.

In the past, houses were made from wood and bamboo but concrete has long been the material of choice and is naturally heavier and not so pliable. The Ministry of Public Works, however, issues guidelines to builders about the construction of buildings in quake-prone areas.

In terms of monitoring the country, BMG divides Indonesia into five regions: Medan, North Sumatra; Jakarta, Java; Denpasar, Bali; Makassar, Sulawesi; and Jayapura, Irian Jaya. Monitoring stations in each of these regions use Indonesia's Palapa satellite to relay real-time information back to BMG headquarters.

As with any period of uncertainty, be it during power outages, volcanic eruptions or earthquakes, the public reach for the phone to call relevant officials for information. Up to now, this has been a problem for the agency, as there is a limited number of telephone lines. BMG, however, has just established a new information service.

"Every time there is a quake, the telephone lines are jammed. To counter this, I've installed a new telephone system which will have all the information about new earthquakes. It'll make our office more efficient. This facility is available to the public," said Sri Diharto.

Recent reports have been saying that with the increasing number of quakes in the capital, Jakarta can expect a sizable earthquake. Sri Diharto, however, refutes this.

"It depends on the scientific approach. People have their own ideas, and whatever the newspapers say becomes the news. We are an official agency and can only tell the public what has happened. If we look back over the last 100 years, there have been no severe earthquakes in Jakarta.

"There have been numerous quakes in Jakarta over the last few months but none of the many high-rise buildings in the capital have collapsed. Even small magnitude quakes could cause them to fall down if they were not built correctly and according to procedures. We've seen some damage in some of the older buildings though, such as City Hall, which developed cracks after a quake in 1996."

Seismologist and head of the National Earthquake Center, based at BMG headquarters, Suhardjono says the Indoaustralia plate, which Jakarta sits on, is getting deeper each year, meaning the likelihood of a strong earthquake in the capital is remote.

But when earthquakes do occur, he said, people should "get out of the house, if they can. But earthquakes happen so quickly and only last a short time. Therefore, if you live in a high-rise building, you should know your surroundings so that you can get under the nearest table or chair. These are the safe things to do. It's not always advisable to stand under a door frame because sometimes it's not strong enough and can collapse."

Suhardjono said people living in high-rise buildings should hold drills twice a year so that they would know what to do in the event of a quake.

"Outside, you've got to watch the ground, because it sometimes opens up. Going to a beach is not a good idea as sometimes the water recedes and there are lots of fish stranded. People go and collect them and are drowned when the sea quickly comes back in. This is what happened a long time ago in France."

After the tremors, houses should be inspected for cracks, he said.

-- BMG's earthquake information hotline numbers are 654-6316 and 420-9103.