Quito, May 23 --(EFE)-- Five earthquakes and 41 hybrid events were registered
Sunday in Mt. Guagua Pichincha, which rises above the Ecuadorian capital, the
Geophysical Institute of the National Polytechnic School announced.

A water vapor explosion was followed by a brief tremor Saturday at 11:44 p.m.
(0444 GMT), a press release sent to EFE explained.

The explosion spewed ashes to the north and west of the crater and some rocks
were displaced on the mountain's northwestern face.

Hybrid events are a mixture of volcanic and tectonic earthquakes, which entail the
rupture of rocks and long-lasting tremors as a result of movements of fluids under
the volcano.

Quito's city government has had a yellow alert in effect in the area since last
October, when ``abnormal activity'' was first reported in the volcano.