Jaggar — Activity of Mauna Loa. 



623 



instantaneous sympathy with the eruption of Mauna Loa was 

 shown by Kilauea, yet there was a very pronounced rise of the 

 Kilauea lava column which immediately followed the date of 

 the Mauna Loa outbreak November 25. (Fig. 2.) 



The seismic prelude to the eruption has been described by 

 H. O. Wood.* The number of local shocks per month was as 

 follows : 



April 17 shocks. August-September, incompletely recorded. 



May... 11 " October 14 shocks. 



June... 13 " November *74 " 



July... 34 " December 13 " 



Fig. 2. 



I! 



P,T JAN FEB MAR APR MAY JUN 



FEET 



IOO 



DOWN 



4" 370D 



JUL AUdSEP DCTNDV DEC 



3E00 



340D 



4DQ 



Fig. 2. Diagram showing rise of lava column of Kilaiiea volcano, in 

 Halemaumau Pit during year 1914, and rapid acceleration after November 

 25, the date of Mauna Loa outbreak. By T. A. Jaggar. 



During the year preceding October 1914 there were at least 

 two sharp shocks on Hawaii, one of them in the Mauna Loa 

 axis ; and in July and September there were seismic spasms of 

 numerous earthquakes lasting two or three days. The com- 

 puted distance of origin of many of the local earthquakes of 

 the year, notably from September to December, corresponded 

 to the distance from the Observatory to the Mauna Loa rift 

 line, namely eighteen to thirty miles. Immediately after the 

 outbreak, from November to December 8 inclusive, eleven 

 days, no earthquakes were registered at the Observatory, show- 



*The Seismic Prelude to the 1914 Eruption of Mauna Loa, by Harry O. 

 Wood, Bull. Seis. Soc. Amer., vol. v, pp. 39-50, March 1915. 



