UPDATE 1-Chile volcano prompts new evacuations, flights to Argentina cancelled
(Adds new evacuations, LATAM Airlines' with normal operations, comments from head of geological service)
SANTIAGO, April 24 (Reuters) - Chilean volcano Calbuco, which erupted without warning on Wednesday, is still puffing out ash and smoke on Friday, prompting new evacuations and leading airlines to cancel flights to Argentine capital Buenos Aires, some 1,400 kilometers east.
Calbuco, considered one of the most dangerous along Chile's chain of around 2,000 volcanoes, erupted twice in 24 hours on Wednesday and Thursday, sending up a spectacular 17 kilometer-high (11 miles) cloud and coating nearby towns in a thick layer of grey ash.
Authorities have set up a 20 kilometer (12 mile) cordon around Calbuco, which is located in the scenic Los Lagos region, around 1,000 kilometers (621 miles) south of capital Santiago.
An increase in volcanic activity caused potentially deadly lahars, a mix of water and rock fragments that flow down a volcano's slopes and river valleys, prompting authorities to evacuate an additional 2,000 people.
"This is a complex (volcanic) process that could last for weeks," said Rodrigo Alvarez, head of Chile's mining and geological service.
Television images showed residents in a town close to Lake Chapo quickly driving down ash-laden streets away from the smoldering volcano. Some houses and schools located close to the volcano have collapsed under the weight of the ash.
The ash also presents a threat to air traffic, as particles in the atmosphere can cause problems for planes.
With winds blowing the ash cloud north-east into neighboring Argentina, Argentine air traffic was the worst affected by Friday. Continuación...