﻿ERUPTION 
  OF 
  MAUN 
  A 
  LOA 
  — 
  MACDONALD 
  

  

  205 
  

  

  orange 
  to 
  pale 
  yellow, 
  indicating 
  temperatures 
  in 
  the 
  vicinity 
  of 
  900° 
  to 
  

   1050° 
  C. 
  Irregular 
  shreds 
  of 
  molten 
  lava, 
  many 
  of 
  them 
  several 
  feet 
  

   across, 
  were 
  hurled 
  into 
  the 
  air 
  (pi. 
  1, 
  fig. 
  2), 
  accompanied 
  by 
  the 
  

   constant 
  evolution 
  of 
  large 
  volumes 
  of 
  fume. 
  The 
  magma 
  shreds 
  

   gradually 
  cooled 
  during 
  flight, 
  and 
  changed 
  in 
  color 
  to 
  red 
  and 
  then 
  

   to 
  purple, 
  and 
  many 
  of 
  them 
  to 
  black 
  before 
  they 
  struck 
  the 
  ground. 
  

   Most 
  fell 
  back 
  into 
  the 
  vents, 
  but 
  occasionally 
  showers 
  of 
  ejecta 
  struck 
  

   the 
  outer 
  slopes 
  of 
  the 
  cones 
  in 
  splashes 
  of 
  fiery 
  red 
  liquid. 
  The 
  

   fume 
  cloud 
  ranged 
  in 
  color 
  from 
  white 
  to 
  bluish-gray 
  and 
  pale 
  

   reddish-brown, 
  the 
  latter 
  color 
  being 
  predominant. 
  The 
  cloud 
  smelled 
  

   strongly 
  of 
  sulfur 
  dioxide. 
  The 
  ground 
  in 
  the 
  vicinity 
  of 
  the 
  vents 
  

  

  500FT 
  

  

  Older 
  I 
  a 
  vas 
  

  

  NTT. 
  

  

  Furnin 
  

  

  Older 
  

  

  lavas 
  

  

  Figure 
  2. 
  — 
  Geologic 
  sketch 
  map 
  of 
  the 
  vent 
  area 
  at 
  9,200 
  feet 
  altitude 
  during 
  the 
  

   eruption 
  of 
  Mauna 
  Loa, 
  on 
  May 
  2, 
  1942. 
  

  

  was 
  constantly 
  agitated, 
  the 
  tremor 
  resembling 
  that 
  caused 
  by 
  the 
  close 
  

   passing 
  of 
  a 
  heavy 
  railroad 
  train. 
  

  

  The 
  pahoehoe 
  flows 
  extruded 
  at 
  the 
  beginning 
  of 
  the 
  eruption 
  were 
  

   cool 
  enough 
  to 
  walk 
  over, 
  but 
  too 
  hot 
  to 
  sit 
  on 
  for 
  more 
  than 
  a 
  few 
  

   minutes. 
  Food 
  was 
  easily 
  cooked 
  over 
  hot 
  cracks 
  in 
  the 
  lava, 
  and 
  

   glowing 
  rock 
  could 
  be 
  seen 
  at 
  depths 
  of 
  a 
  few 
  inches. 
  The 
  odor 
  of 
  

   boric 
  acid 
  was 
  detected 
  at 
  several 
  cracks 
  in 
  the 
  lava, 
  and 
  the 
  so-called 
  

   foundry 
  odor, 
  resembling 
  the 
  smell 
  of 
  hot 
  iron 
  in 
  a 
  blacksmith 
  shop, 
  

   was 
  constantly 
  present. 
  The 
  lava 
  was 
  exceedingly 
  frothy. 
  Thin 
  

   shells 
  2 
  or 
  3 
  inches 
  thick 
  covered 
  cavities 
  a 
  few 
  inches 
  to 
  2 
  or 
  3 
  feet 
  

   deep 
  and 
  several 
  feet 
  across. 
  Many 
  of 
  these 
  cavities 
  were 
  pahoehoe 
  

   tubes, 
  but 
  others 
  ended 
  in 
  lobes 
  against 
  the 
  adjacent 
  older 
  lava 
  with 
  

   no 
  possible 
  means 
  of 
  escape 
  for 
  any 
  enclosed 
  liquid. 
  The 
  latter 
  cavities 
  

   are 
  probably 
  the 
  result 
  of 
  inflation 
  by 
  expanding 
  gases 
  in 
  the 
  highly 
  

   gas-rich, 
  fluid 
  pahoehoe. 
  

  

  