82 PRATT. 



people were killed out of a total population of 180, and this proportion 

 would probably have been the same if 26,000 people had been living in 

 Gulod, as there were in St. Vincent. 



RESUME, 



First, the eruption of Taal Volcano which occurred January 30, 1911, 

 was probably the most severe, considering the number of lives lost and 

 the damage caused, the area of the region aifected and the changes 

 wrought in the volcano itself, which has occurred in historic times in the 

 Philippines. It was of the explosive type, the violent activity con- 

 tinuing only a few hours, and the attendant phenomena being typical 

 of this class of eruption. 



Second, the principal ejecta from Taal Volcano during this eruption 

 were steam and volcanic ash or mud. Some incandescent stones were 

 thrown out. The volcanic ash or mud probably resulted from the at- 

 trition, by mutual friction within the cloud, of bedded tuff which was 

 torn from the floor of the crater. Little, if any, ejecta came (recently) 

 from a great depth. The mud or ash spread over an area of 2,000 square 

 kilometers. 



Third, the violent action of the eruption was more effective to the 

 west of the volcano, due largely to the contour of the crater rim. 



Fourth, a system of earth fissures opened during the eruption, the trend 

 of which indicate a tectonic line passing through Balayan Bay, Taal Vol- 

 cano, along the probable fault block, the eastern scarp of which is marked 

 by Mount Gonzales, and through Laguna de Bay. Tovms along this line 

 near the volcano suffered most from the earthquakes accompanying the 

 eruption, and are most liable to damage from earthquakes during pos- 

 sible future eruptions. 



Fifth, general subsidence of the ground level took place over a con- 

 siderable area after this eruption. The island on which the volcano is 

 located subsided and the surrounding lake changed its level. The cra- 

 ter was materially deepened through the removal of material from its 

 floor. 



Sizth, the most significant thing about this eruption is the probability 

 that aU its solid ejecta were surface material and the apparent absence 

 even at the seat of volcanic activity of molten lava, which most theories 

 of vulcanism require to account for this type of eruption. 



Seventh, the chief agent of destruction and the main cause of death 

 resulting from the eruption was the explosive expansion of the escaping 

 steam, which was violent owing to its movement and suffocating owing 

 to its heat, its burden of mud, and a content of sulphur dioxide. 



It is remarkable to be able to sum up perfectly the phenomena of 



