Mount Pinatubo’s eruption on June 15, 1991, is considered the second largest volcanic eruption of the 20th century. It is also a case study on the importance of preparedness in reducing casualties from natural calamities.

Mount Pinatubo did not fail to warn communities living near the slopes before its imminent eruption. In March 1991, months before the volcano unleashed its full fury, a group of Aetas living in the upper slopes of Mount Pinatubo felt minor earthquakes (with magnitudes not greater than 4) around the volcano.

Source: http://www.rappler.com/move-ph/issues/disasters/96424-1991-mount-pinatubo-eruption