A major earthquake north of Concepcion, Chile has disrupted communication and electricity infrastructure though President Bachelet says emergency response is proceeding as planned. "The quake struck at 0634 GMT about 91km (56 miles) north-east of the city of Concepcion and 317km south-west of the capital, Santiago. President Michelle Bachelet also said a large wave had affected one southern island group and she appealed for the Chilean people to remain calm. The US issued an initial tsunami warning for Chile, Peru and Ecuador. That was later extended to Colombia, Antarctica and Central America. Japan's meteorological agency warned of a potential tsunami across large areas of the Pacific. Santiago airport has been closed and all flights cancelled until further notice, airline officials say. President Bachelet called on people to remain calm and contact the authorities if they needed help. She said a "wave of large proportion" had affected the Juan Fernandez island group, reaching halfway into one inhabited area. She said if there were more aftershocks, people in coastal areas should go to higher ground. Ms Bachelet warned people not to travel on roads in affected areas as a number of bridges were down. Chilean officials said the worst affected town appeared to be Parral, close to the epicentre. Chilean television said there had been a fire involving chemicals in the town of Colina, 20km north of Santiago, but that it was now under control. Several hospitals have had to be evacuated in a number of areas, including Santiago, because of structural damage. Many of Chile's news websites and radio stations are still not accessible."