September 28, 1965 Tsunami: Taal, Luzon Island, Philippines

1965, Sept 28. Estimates range 150 to 355 including those drowned and several murdered. Witham lists range of 190-355. Many of the fatalities occurred when tsunami capsized boats filled with fleeing residents. Newspaper and other reports suggesting 3,000-5,000 deaths are very unreliable. (reference #9675)

A moderately violent phreatomagmatic explosive eruption of Taal Volcano, in the Philippines, occurred from 28 to 30 September 1965. The main phreatic explosions, which were preceded by ejection of basaltic spatter, opened a new crater 1.5 kilometers long and 0.3 kilometer wide on the southwest side of Volcano Island in Lake Taal. The eruption covered an area of about 60 square kilometers with a blanket of ash more than 25 centimeters thick and killed approximately 190 persons. ..

The explosions within the crater area produced shock waves that generated water waves, which probably reached

maximum height between Volcano Island and the west shore of Lake Taal. These waves capsized some of the boats filled with the fleeing residents of the island and accounted for many of the fatalities. The maximum height of the waves is not known, because evidence of wave height during the early, most violent phase of the eruption is now covered by layers of ash. However, on the west shore of Lake Taal, directly west of the mouth of the explosion crater, there is clear evidence that waves reached 4.7 meters above lake

level and swept inshore as much as 80 meters. The debris left by these waves is on top of the air-fall ash, hence the waves must have occurred very late in the eruption. Undoubtedly much larger waves swept that coast earlier.

A streamflow gage 1.5 kilometers downstream from the outlet of Lake Taal shows an increase of flow from an average of 20,500 liters per second for several days before the eruption to a maximum of 28,400 liters per second on 28 September, followed by decreases to 23,800 liters per second

on 29 September, and 22,800 liters per second on 30 September. Such an increase is probably due to excessive

wave action and to seiches produced by the explosion shock waves, as well as to displacement of water by the ash fall and to the inordinately heavy rain that accompanied the eruption.

(above from reference #5094)

Many of the 190-355 fatalities occurred when tsunami waves capsized boats containing residents fleeing from Taal Island to the western shore of the lake (near Agoncillo). The waves inundated areas up to 4.7 m above the level of the lake (Moore et al. 1966). (reference #12533)