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  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1943 
  

  

  The 
  latest 
  period 
  of 
  activity 
  of 
  Mauna 
  Loa 
  commenced 
  on 
  April 
  

   26, 
  1942. 
  A 
  fissure 
  opened 
  across 
  the 
  caldera 
  and 
  a 
  short 
  way 
  down 
  

   the 
  northeastern 
  slope, 
  and 
  lava 
  fountains 
  played 
  along 
  it. 
  Two 
  

   days 
  later 
  the 
  principal 
  eruption 
  began 
  along 
  a 
  fissure 
  in 
  the 
  north- 
  

   east 
  rift 
  zone, 
  at 
  an 
  altitude 
  of 
  9,200 
  feet. 
  Activity 
  continued 
  until 
  

   May 
  10, 
  1942. 
  The 
  last 
  preceding 
  activity 
  had 
  been 
  in 
  1940, 
  when 
  

  

  156° 
  

  

  155° 
  

  

  156° 
  155° 
  

  

  Figure 
  1.— 
  Outline 
  map 
  of 
  the 
  island 
  of 
  Hawaii, 
  showing 
  the 
  location 
  of 
  the 
  1942 
  

   lava 
  flow 
  (solid 
  black), 
  and 
  other 
  historic 
  flows 
  of 
  Mauna 
  Loa 
  and 
  Kilauea. 
  

  

  lava 
  fountains 
  played 
  in 
  the 
  summit 
  caldera 
  with 
  gradually 
  abating 
  

   strength 
  from 
  April 
  7 
  until 
  August. 
  

  

  The 
  following 
  account 
  of 
  the 
  eruption 
  of 
  1942 
  is 
  based 
  partly 
  on 
  

   personal 
  observation 
  and 
  partly 
  on 
  data 
  gathered 
  from 
  other 
  ob- 
  

   servers. 
  The 
  activity 
  at 
  the 
  vent 
  at 
  9,200 
  feet 
  was 
  watched 
  at 
  close 
  

   range 
  throughout 
  its 
  duration 
  by 
  a 
  succession 
  of 
  witnesses, 
  but 
  the 
  

   early 
  summit 
  activity 
  was 
  seen 
  only 
  from 
  a 
  distance. 
  Most 
  of 
  the 
  

  

  