The US Geological Survey (USGS) on Wednesday issued a red alert for the eruption of the Kilauea volcano in Hawaii, which led to the evacuation of hundreds of people from the area last week.
A red alert means a "major volcanic eruption is imminent, underway, or suspected", Efe news reported citing a statement on the USGS website.
"Ash eruption at the summit has increased in intensity. NWS (National Weather Service) radar & pilot reports show the top of the ash cloud is as high as 10,000-12,000 feet (3,000-3,600 metres) above sea level," the agency said in a statement.
"At any time, the activity may become more explosive, increasing the intensity of ash production and producing ballistic projectiles near the vent," the statement said, although it added that activity might vary in intensity.
Local authorities have warned residents near the volcano to be prepared to be evacuated at short notice or directly without any previous warning.
The 1,700 people evacuated earlier are still staying away from their houses.
The eruption started on May 3 and around 20 fissures have opened up since then, with the lava destroying dozens of homes.
A number of earthquakes have also been registered, with the biggest tremors reaching magnitude 5.0.
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