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By Heri Retnowati
SUGIHWARAS, Indonesia, Nov 3 (Reuters) - Indonesia’s Mount Kelud volcano has erupted, according to seismographic signals, but no signs of ash or lava could be seen because of heavy cloud cover, a top official said on Saturday.
An estimated 350,000 people live within 10 km (6 miles) of the volcano, which is about 90 km southwest of Surabaya, Indonesia’s second-largest city and one of its busiest airports.
In Sugihwaras, a village 8 km from the crater that suffered casualties and was badly damaged during an eruption in 1990, many people panicked when they heard the reports.
"The mosque announced that Kelud had erupted and there was a half hour to evacuate," said Ngatijo, a villager.
When Mount Kelud erupted in 1990 at least 30 people were killed. In 1919, about 5,000 died as Kelud ejected scalding water from its crater lake.
Saut Simatupang, an official at Indonesia’s Centre for Vulcanology and Geological Hazard Mitigation, told Reuters continuous tremors had been detected, indicating an eruption, but this was impossible to confirm visually because of the heavy cloud in the area.
"There is heavy cloud over there, so even ash could not be seen. But instrumentally it has erupted, as shown by the seismographic records that were over the scale," he said.
The authorities have been monitoring the volcano in East Java for several weeks and raised its alert status to the highest level about two weeks ago as its activity increased and an eruption appeared imminent.
The volcano’s crater lake makes it much harder to monitor than others, but in recent weeks the lake temperature has risen and the frequency of tremors has increased.
Indonesia has the highest number of active volcanoes of any country, sitting on a belt of intense seismic activity known as the "Pacific Ring of Fire".
Indonesian officials are also closely monitoring three other volcanoes for increased activity. (Additional reporting by Telly Nathalia in Jakarta)