94: J. D. Dana — Eruptions of Kilauea and Mt Loa. . 



C. H. Hitchcock, and gave it exit nearly all the way, occasion- 

 ing their rapid progress seaward. 



Here then it is clear what the earthquakes did to produce 

 the eruption. They, or the cause generating them, broke a 

 hole into the conduit, and the lava escaped. The lava of the 

 conduit was not thrown into commotion or projected to great 

 altitudes at the summit ; instead, it sank out of sight, follow- 

 ing the rent to the surface far down the mountain. These 

 events were repeated almost precisely in the Mt. Loa eruption 

 of 1887. The locus of the outflow and of the earthquakes in 

 both cases was far south in southern Hawaii, and the two 

 streams followed near and parallel lines ; the chief difference 

 between them was in the higher outlet in 1887 by 2500 or 

 3000 feet (see map, page 82). 



The earthquake eruption of Kilauea was coincident with 

 the first of the two Mt. Loa eruptions in April, 1868. The 

 earthquakes were the same identical earthquakes ; and that 

 "terrible shock" of April 2d was for each the special discharg- 

 ing agent. Immediately after the shock the fires of Kilauea, 

 before unusually active,* commenced to decline ; by night of 

 that Thursday, all the burning cones, by night of Saturday all 

 the smaller lava-lakes, and by Sunday night, the great South 

 Lake, had become extinct. And then, the lavas having run 

 off, half the floor of the crater sunk down 300 feet. 



A genetic connection between the earthquake disturbance 

 and the eruption cannot be doubted. The earthquakes came 

 after the crater had reached a state of unusual activity, and 

 hence could have taken no part in the preparation. They 

 simply discharged the lava by breaking the conduit that held it. 



Moreover, the earthquakes which thus emptied Kilauea were 

 of Mt. Loa origin ; they had their center thirty miles or more 

 west of Kilauea, and were made through the Mt. Loa fires. It 

 is a case, therefore, of one mountain-volcano accidentally dis- 

 charging the conduit-lava of another. The work was simply a 

 fracturing of the mountain in different directions ; for the 

 island was violently shaken from the west side to Hilo on the 

 east coast ; and, in the general fracturing, the two volcanic 

 conduits were broken at once, an accident not likely to often 

 happen. 



It is also to be noted that the earthquakes viere of local or 

 volcanic origin. This is established by the fact that only two 

 of the heaviest shocks reached westward to Honolulu on Oahu 



* Dr. Hillebrand states that for two months previous to the eruption there were 

 eight lava-lakes in the bottom; and until March 17th, a very active blow-hole in 

 the northwest corner, where " large masses of vapor were thrown off as from a 

 steam engine " on Thursday, April 2d, after the earthquake, there were fearful 

 detonations in the crater, and portions of the wall tumbled in ; and then began 

 the decline. 



