A brief calm Thursday in Ecuador's rumbling Tungurahua volcano could be a sign that a violent eruption is coming, experts warned according to AP. «This calm the volcano is showing is typical of very strong, explosive events,» Jorge Bustillos, a vulcanologist at Ecuador's Geophysics Institute, told The Associated Press. The 16,575-foot (5,023-meter) volcano in central Ecuador has been active since 1999 and been spitting out ash and gases intermittently since late last year. On Wednesday, the volcano shot ash miles (kilometers) into the sky, and caused significant damage to farms near the volcano. But on Thursday the volcano appeared calm. Civil Defense officials said they have evacuated 1,500 villagers living near Tungurahua's flanks, half the number the government said must be evacuated from the volcano-side hamlets. «We're maintaining a red alert,» said Juan Salazar, mayor of the village of Penipe near the volcano slopes. «The people are worried because they know (this) could mean a big explosion later.» Experts at the Geophysics Institute warned that the intense activity shows no sign of slowing down, and compared it to the massive 2006 Tungurahua eruptions that buried entire villages, leaving at least four dead and thousands homeless.