350 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 60 



EP-' — ^ 



;\'.'^$-Xy Slopes of 



'■'• .' ■• .~\-'"oN~« Mauna Loa 



.,'. '.Kilauea ^'^\V-:r-> 

 •,V / ' fr3'«*£Ii^ 1959 activity - : 





KK'"" 



Mauna 

 50 100 ISOmilcs Kilauea 



LANAl 

 KAH001.AWE 





I55°00' 



Figure 1. — Oblique perspective of a portion of the Island of Hawaii, showing the 1959-60 

 eruption sites on the summit and east rift zone of Kilauea Volcano. Vertical scale is 

 exaggerated. Small-scale inset map shows principal islands in the Hawaiian Archipelago. 



Within this large summit caldera of Kilauea is still another smaller 

 depression, known as Halemaumau, the usual site of Kilauea summit 

 eruptions. 



The 1959-60 eruptive episode of Kilauea had its real beginning 

 months before the first surface outbreak and miles beneath the Kilauea 

 summit. Between October 1958 and February 1959, analysis of data 

 from the U.S. Geological Survey's liquid-level tiltmeter bases,^ in- 

 stalled around the summit, indicated that the whole caldera region 

 was swelling upward, suggesting that magma was welling up quietly 

 from the depths and accumulating in a zone several miles beneath 

 the caldera. Following several moderate earthquakes during Feb- 

 ruary 1959, the swelling stopped; and from May until August the 

 summit slowly subsided. In August a great swarm of earthquakes 

 and tremors originating about 35 miles beneath the caldera was re- 

 corded by the U.S. Geological Survey's seismograph net on Hawaii. 

 Magma moving into the deep volcanic plumbing system during this 

 period made itself felt at the surface shortly, for rapid swelling of 

 Kilauea resumed. In mid-September a very sensitive telerecording 

 seismograph at the northeast edge of Halemaumau began recording 

 a swarm of tiny quakes originating less than half a mile away. Al- 



^ Piers for a portable water-tube leveling system which Is capable of measuring very 

 small differences In the inclination of the land surface. 



