J. D. Dana — Eruptions of Kilauea and Mt Loa. 93 



The escaping vapors have spent their force mostly in making 

 jets and fountains and feeble outflows ; and still more quiet 

 has been the work of the ascensive force. Eruptions have been 

 a sequel to years of this quiet work, but not a direct effect of 

 the action. 



3. Agency of Earthquakes. — Earthquakes have often been 

 considered an effective agent in eruptions. But during the 

 past sixty-five years only two of the eruptions of Mt. Loa and 

 one of Kilauea have been introduced or attended by noticeable 

 earthquakes. The eruptive agent in both volcanoes has in 

 general worked quietly, " as quietly as the moon rises," says 

 one writer, without much exaggeration. The star-like light on 

 Mt. Loa has been followed soon by a stronger glow ; and, ac- 

 companying this, a rising of clouds into heaps and lofty 

 columns. After a day or two or three, the summit-light 

 having disappeared, the flow has begun one, two, or three 

 thousand feet below the top ; and a line of light has then 

 slowly lengthened down the mountain for twenty or thirty 

 miles ; and all this, quietly. It is the grandest of volcanic 

 work with the least possible display of force. 



The facts connected with the two eruptions of Mt. Loa 

 and one of Kilauea, that were attended by earthquakes, merit 

 special review in this place because they teach what earth- 

 quakes may do, and by w T hat means. The three occurred in 

 the years 1868 and 1887. 



On a Friday in 1868, March 27' (p. M and xxxiv, 91), a 

 light was seen on the mountain and feeble earthshocks oc- 

 curred. Only slight eruptions followed. Then, in accordance 

 with the ordinary rule, these first fires at the summit dis- 

 appeared. But the earthquakes increased in violence — not 

 about the summit, but far to the southward, within the lower 

 three or four thousand feet of the mountain. And they con- 

 tinued increasing until that " terrible shock" of Thursday, April 

 2d. Five days later, April 7th, the lava burst out from an 

 opened fissure at a point, 23 miles distant from the summit 

 and only 10 or 11 from the sea-coast. 



It is here manifest that the earthquakes had nothing to do 

 with preparing for the eruption ; they were too late for this. 

 It is possible that the first break near the summit anticipated 

 the first earthshock But below, in the region of most violent 

 disturbance, greater fissures were opened, the profoundest prob- 

 ably at the very time of that " terrible shock ;" and as soon 

 after as the subterranean passage could be made — about five 

 days — the lava from the broken lava-conduit or reservoir made 

 its appearance at the surface and hurried down the moun- 

 tain to the sea. But at the sea-border and elsewhere the 

 fissures were probably ahead of the lava, according to Professor 



