More than 300 families have been evacuated after massive amounts of ash billowed from the Mayon volcano over the weekend due to the collapse of lava deposits from its slopes, Philippine officials said on Monday.There was no explosive eruption from Mayon, which has been erupting mildly on and off since January, but huge deposits of lava on its southwestern slope suddenly cascaded down in a pyroclastic flow – an avalanche of hot rocks, ash and gas – before nightfall on Saturday, said Teresito...