Eruptions at Indonesia's deadly volcano appeared to be intensifying Thursday as towering clouds of ash shot from the crater with a thunder-like roar, dusting towns up to 150 miles away and forcing motorists to switch on their headlights during the day.The death toll climbed to 44 — with six more casualties recorded in the last 24 hours — and the government repeated orders to airlines to stay clear of the unpredictable mountain.Mount Merapi, which means "Fire Mountain," is one of the world's most active volcanoes.But even those who have dedicated a lifetime to studying it have been baffled by its erratic behavior since its first Oct. 26 eruption, which has been followed by more than a dozen other powerful blasts and thousands of volcanic tremors.They'd earlier hoped that would result in a long, slow release of energy."But we have no idea what to expect now," said Surono, a state volcanologist, adding that he has never seen the needle on Merapi's seismograph working with such intensity.The fear is that a new lava dome forming in the mouth of the crater will collapse, triggering a deadly surge of up to 1,800 degree Fahrenheit ash and gas — known to experts as pyroclastic flows — at speeds of 60 miles per hour. Though more than 75,000 people living along its fertile slopes have been evacuated to crowded emergency shelters away from the crater, dozens risk their lives to return during periods of calm to check on their livestock and homes.With no winds early Thursday, white clouds from Merapi fired a spectacular 20,000 feet into the sky. Gusts later carried the smoke westward, dusting roof tops, trees and laundry lines far away with thick white powder. Rain pounded the region later in the day, clogging mountainside rivers with molten rocks and debris.Activity at Merapi has at times briefly forced nearby airports to close and the Transportation Ministry reiterated Thursday that flight paths near the mountain had been shut down for safety reasons.Officials insisted, however, that a Qantas jetliner forced to make an emergency landing after one of its four engines failed over Batam, an island 800 miles to the west, was unrelated."There was no connection with Mount Merapi," said Bambang Ervan, a spokesman for the Transportation Ministry. "It was too far from the volcano — the sky over Singapore and Sumatra island is free of dust."Merapi has killed at least 44 people since Oct. 26, said Eka Saputra, a disaster official, raising the toll after three people died in a ferocious eruption Wednesday and another succumbed to injuries from an earlier blast. The cause of the other two most recent deaths was not clear.In 1994, 60 people were killed, while in 1930, more than a dozen villages were torched, leaving up to 1,300 dead.Mount Merapi's "danger zone" was widened for the second time in as many days Friday following another booming explosion around midnight. Subandrio, a state volcanologist, said people living in villages and emergency camps within 12 miles of the crater were told to clear out.Thousands of men, women and children were loaded into trucks and taken to stadiums in cities far from the mountain, while others, covered in soot, jumped onto motorcycles and into cars.Indonesia, a vast archipelago of 235 million people, is prone to earthquakes and volcanos because it sits along the Pacific "Ring of Fire," a horseshoe-shaped string of faults that lines the Pacific.The volcano's initial blast occurred less than 24 hours after a towering tsunami slammed into the remote Mentawai islands on the western end of the country, sweeping entire villages to sea and killing at least 428 people.There, too, thousands of people were displaced, many living in government camps.