All 22 of the early-warning buoys Indonesia deployed after the 2004 tsunami disaster were inoperable when a massive undersea earthquake struck off the coast on Wednesday, a National Disaster Mitigation Agency official says.
The 7.8-magnitude quake did not trigger a tsunami, and there were no deaths and no major damage, but it did expose gaps in the systems put in place to prevent a disaster similar to the Indian Ocean quake that killed more than 200,000 people 11 years ago.
In addition to the malfunctioning of buoys designed to warn of massive waves, authorities said there were not enough evacuation routes or shelters in Padang, a Sumatra island port city of around one million people that felt the quake.
"There was definitely panic last night, that cannot be denied," said Zulfiatno, the head of the disaster management agency in Padang who uses only one name, adding that shelters had the capacity to only hold around 200,000 people.
"But the situation has improved from previous years. People have started to understand how to evacuate safely."
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The 9.15-magnitude quake of December 2004 opened a fault line deep beneath the ocean, triggering a wave as high as 17.4 metres that crashed ashore in more than a dozen countries to wipe some communities off the map in seconds.
Indonesia straddles the so-called "Pacific Ring of Fire", a highly seismically active zone, where different plates on the earth's crust meet and create a large number of earthquakes and volcanoes.
The province of Aceh on the northwest tip of Sumatra bore the brunt of the 2004 tsunami, with at least 168,000 killed.
Soon after that disaster, Indonesia introduced a sophisticated early warning system using buoys, sea-level gauges and seismometers that can send alerts to countries' tsunami warning centres within 10 minutes of a quake.
Officials said the procedure is to issue a tsunami warning if a quake of more than 6.5 magnitude and with its epicentre less than 20 km deep happens at sea, and that went smoothly on Wednesday.
But the buoys, which measure the force and speed of water movement, were a missing link in the chain, with many damaged or inoperable.
There were 11 aftershocks during the night following the main quake, but authorities called for calm as they had diminished in strength.
