Indonesia has launched a new tsunami early warning system, designed to give people in coastal areas enough time to escape tsunamis before they reach land.
But experts involved in setting up the system admit that some areas of the country, including the province of Aceh, are not fully protected by it.
The project is a direct result of the devastating Indian Ocean tsunami which hit the country in 2004.
A quarter of a million people died, more than half of them in Aceh.
The new early warning system was launched in Jakarta by Indonesian President Susilo Bambang Yudhoyono.
But Dr Lauterjung, a spokesman for the German government which is assisting in the programme, said that deep sea buoys - the Deep-ocean Assessment and Reporting of Tsunami (Dart) system - responsible for detecting changes in sea levels had not yet been installed around the islands of Bali, Flores and the northern part of Sumatra, which includes Aceh, meaning there would be a "time delay" in predicting a tsunami.
DART EARLY WARNING SYSTEM
1. Recorder on seabed measures pressure and sends data to buoy. 2. Buoy also detects changes in sea level and motion. Tide gauges, usually sited on land, detect tidal changes. 3. Information is transmitted via satellite to ground stations which assess risk of tsunami.
Around a third of the seismographs stipulated in the government's plan are also not yet in place.
And Dr Sri Woro, the head of Indonesia's meteorological agency, said there were still what she called "infrastructure problems" in making the network of sensors and stations work smoothly together.
Tuesday's ceremony marked the formal launch of the system, which is expected to be fully completed by 2010, though much of it is already operational.
Since the Indian Ocean tsunami four years ago, Indonesia has experienced two other waves along its Javan and Sumatran coastlines.
The last of these, in September last year, was successfully predicted by the new system.
The new system relies on three main parts: first, seismographs warn of any earthquakes that are likely to trigger a tsunami, then satellites monitor changes in the earth's crust, while tide gauges and deep-sea buoys measure whether sea levels are actually changing as a result.
Indonesia sits at the meeting point of three of the earth's tectonic plates and almost 60% of its vast coastline is at risk of tsunamis.
The new network has been built with the help of several foreign donors, including Germany, Japan and China.
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