ERUPTION OF TAAL VOLCANO. 69 



and Lemery were most shaken. In Lemery the tower of the Casaysay 

 Church was partly demolished. (See Plate XII, fig. 1.) Masonry gate- 

 posts in the wall which surrounds the church were overturned and fell to 

 the west. This church is directly in the line of one of the fissures and 

 some of the damage is evidently due to the vertical displacement along it 

 as the west side dropped. With the exception of the fissuring, which is 

 usually connected with more intense earthquakes, the evidence in Taal 

 and Lemery bears out Father Maso's conclusion that the strongest 

 earthquakes did not exceed intensity VII. ISTumerous small landslides 

 occurred in the steeply eroded hills of volcanic tufE to the west of Lake 

 Bombon. The shocks cracked and displaced several old masonry walls 

 in Talisay. 



Water wave. — It has already been stated that Lake Bombon rose 

 suddenly Just after the main eruption. This wave (or series of waves 

 close together) washed up on the lake shore through a vertical distance 

 of 2.5 or 3 meters carrying away houses and causing loss of life in some 

 of the barrios. If, as seems established, no severe earthquake occurred 

 for some time before this wave was observed, its cause must be sought 

 in another direction. 



It will be brought out in another part of this paper that the whole 

 of Volcano Island sank from 1 to 3 meters during the recent activity. 

 If this subsidence took place in one quick drop, it probably caused a 

 large wave to pass over the lake surface. However, it is inconceivable, 

 considering its size, that the island could be moved suddenly enough, 

 and through a sufficient distance to cause such a water wave, without 

 also producing a very severe earthquake. Moreover, some subsidence 

 had already occurred when Mr. Martin visited the island Sunday 

 morning and observations indicate that there was further subsidence 

 after the activity had become insignificant. It is probable, on the 

 whole, that the island sank gradually, causing only minor earthquakes 

 and very slight disturbance to the lake surface. Comparison of photo- 

 graphs of the crater taken on January 30 and 31, indicates the disap- 

 pearance of certain portions of the margin of the active center at some 

 time between the above dates. See Plate I, fig. 2 and Plate II, fig. 1, 

 in the paper by Charles Martin. 



The explosive rush of gases down the volcano slopes affords a possible 

 explanation of the water wave. This blast, the strength of which is 

 'intimated by the absolute destruction it wrought not only over the whole 

 island but on the west lake shore, moved with a considerable downward 

 component (tending to expand equally in all directions) until the 

 moment it reached the lake level. Eesponding to this downward pres- 

 sure, the lake surface would be depressed, and its reaction would cause 



