Yesterday teams of workers were struggling to clear volcanic ash from Quito's airport, a task expected to take up to six days. The white ash, which made the city look like it had been hit by a snowstorm, clogs jet turbines and makes the runways treacherous for landings and take offs. All flights were being diverted to the port of Guayaquil, Ecuador's second city, and another airport in Latacunga, 55 miles south of Quito.
In an Andean valley almost 9,500ft above sea level, Quito is ringed by nine active volcanoes. Guagua Pichincha, only seven miles from the city, last erupted 340 years ago, but has been rumbling since September. Ash from its 15,700ft crater has shut the airport half a dozen times since then.
Schools were closed after Thursday night's explosion. The mayor, Roque Sevilla, called for calm, told residents to use masks to protect eyes and lungs from abrasive ash and asked them to help sweep the streets. Thieves took advantage of the half-light to steal CDs and equipment from a local radio station, slipping into the studios while guards took shelter from the noxious ash.
Since September, Quito has gone from yellow to orange alert several times - meaning an eruption was likely in days or weeks. But a red alert such as the one declared around Tungurahua - which predicts an eruption in hours - has yet to be reached. An eruption by Guagua Pichincha could shower Quito with a thick rain of dangerous volcanic ash, and would send lava down onto villages below the crater.