Ecuador's Tungurahua volcano, which has been rumbling on and off since 1999, registered a "strong explosion" Sunday, belching ash and gases skyward, the Geophysics Institute reported.

It issued an "orange alert," the second highest warning level under red.

The explosion at the volcano on the eastern Andean range, soaring over 5,000 meters (16,000 feet), came at 0647 local time (1147 GMT) and was heard even in the city of Guayaquil on the Pacific.

The gas and dust could be seen as far away as the capital Quito, about 153 kilometers (95 miles) north of the volcano.

Its name means "Throat of Fire" in the indigenous Quechua language.