QUITO, Ecuador (AP) - A volcano near the capital erupted with a 5-1/2-mile-high cloud of vapor and ash late    Friday, one of the most powerful explosions yet since Pichincha came back to life last year. Prevailing winds were    blowing the volcanic ash away from Quito. The eruption "was a marvelous spectacle, but also frightening," said Quito    Mayor Roque Sevilla. "All indications are that the wind will dissipate the cloud in a matter of hours." He said it    appeared to be one of the largest eruptions since Pichincha awoke from 339 years of inactivity last year. The    15,840-foot volcano that overshadows this city of 1.4 million residents has erupted several times since September.