Activity is intensifying Monday at Indonesia's Mount Merapi with the volcano spewing out near continuous clouds of deadly hot ash and debris, according to eyewitness reports. Villagers who had not left the area were told to stand by for possible evacuation and wait by the side of the road on the slopes of the volcano. One of the eruptions was the most powerful yet, sending ash, rock fragments and volcanic gas almost four kilometers (2.5 miles) down the mountain's western flank, Ratdomopurbo, the region's chief vulcanologist, told the Associated Press. It was followed by several other huge explosions on the crater. Scientists are warning that the mountain's growing lava dome could soon collapse with potentially catastrophic consequences. Indonesian authorities on Saturday ordered the evacuation of thousands of residents near Mount Merapi, which has been rumbling for about a month. "Clearly, it looks like it may be getting much worse," Michael Ramsey, associate professor in the Geology and Planetary Science Department of the University of Pittsburgh said. "You can almost think of it as a cork in a bottle that's being shook up and the pressurization going on underneath there as the new lava moves up can only mean bad things," he said. On Sunday, however, many villagers tried to return to their homes along the slopes of smoking Mount Merapi, news services reported.