THE 



AMERICAN JOURNAL OF SCIENCE 



[FOURTH SERIES.] 



Aet. XXXIX. — Subsidence Phenomena at Kilauea in the 

 Sammer of 1911 : by Frank A. Peeret. 



A column of liquid lava filling the conduit and reaching the 

 crater of a volcano, and, therefore, in communication with the 

 atmosphere, is, like the mercury of a barometer, in a condition 

 of balance, and the same may be said of the rate of emission 

 of its gases. It is, in a way, comparable to a steam engine lift- 

 ing a load against gravity and exhausting against atmospheric 

 pressure, in which any variation in the head of steam, or in the 

 load, or in back pressure against the exhaust, would have a 

 direct effect upon the work done. And, inasmuch as the height 

 of the lava and the rate of gas now directly affect the volcanic 

 edifice and concur in the initiation of actual, external eruption, 

 it behooves the volcanologist to study the variations of the lava 

 column in connection with every possible cause, whether endog- 

 enous, superficial or extra-terrestrial. 



During July, August and September, 1911, the height of the 

 Kilauea lava column was taken by daily triangulations from 

 the writer's observing station and abode on the east brink of 

 Halemaumau, and from these a curve has been plotted as 

 reproduced in fig. 1. The variations in the height of the lava, 

 as shown in the curve, are expressed by the column of figures 

 at the left in meters below the station. From these it will be 

 seen that a rise of five meters in the early part of July brought 

 the lava to the " high water mark " for this season, when it 

 stood at seventy meters below the brink — an elevation which 

 approximates 1114 meters above the sea. From this time to the 

 end of September there was a general subsidence of the lava 

 column, amounting to more than fifty meters, the abnormali- 

 ties of which, with their causes and their immediate effects, are 

 briefly examined in the present paper. 



Am. Jour. Sci.— Fourth Series, Vol. XXXV, No. 209.— May, 1913. 

 33 



