﻿ERUPTION 
  OF 
  MAUNA 
  LOA 
  — 
  MACDONALD 
  209 
  

  

  The 
  front 
  of 
  the 
  lava 
  advanced 
  into 
  a 
  region 
  of 
  dense 
  jungle. 
  

   The 
  only 
  trained 
  scientific 
  observer 
  to 
  reach 
  the 
  flow 
  terminus 
  while 
  

   it 
  was 
  still 
  in 
  motion 
  was 
  Lt. 
  P. 
  E. 
  Schulz,, 
  formerly 
  assistant 
  at 
  the 
  

   Hawaiian 
  Volcano 
  Observatory, 
  who 
  has 
  kindly 
  supplied 
  the 
  writer 
  

   with 
  an 
  excellent 
  description 
  of 
  the 
  advancing 
  lava. 
  Mr. 
  Schulz 
  

   reached 
  the 
  lava 
  flow 
  on 
  May 
  1. 
  The 
  jungle 
  was 
  extremely 
  wet 
  and 
  

   swampy, 
  and 
  much 
  rain 
  water 
  was 
  standing 
  or 
  flowing 
  on 
  the 
  surface 
  

   of 
  the 
  ground. 
  The 
  flow 
  was 
  20 
  to 
  25 
  feet 
  thick, 
  and 
  was 
  typical 
  aa, 
  

   with 
  an 
  exceedingly 
  active 
  front. 
  Trees 
  in 
  the 
  path 
  of 
  the 
  flow 
  were 
  

   rapidly 
  bowled 
  over 
  and 
  burned. 
  Contact 
  of 
  the 
  lava 
  with 
  the 
  water 
  

   and 
  wet 
  vegetation 
  resulted 
  in 
  large 
  volumes 
  of 
  dense 
  smoke 
  and 
  

   violent 
  explosions 
  which 
  made 
  impossible 
  a 
  close 
  approach 
  to 
  the 
  

   flow. 
  

  

  The 
  explosions 
  were 
  frequent, 
  and 
  caused 
  great 
  billowing 
  black 
  

   clouds 
  to 
  rise 
  500 
  to 
  1,000 
  feet 
  in 
  the 
  air, 
  the 
  color 
  of 
  the 
  cloud 
  chang- 
  

   ing 
  after 
  a 
  minute 
  or 
  so 
  to 
  gray 
  and 
  then 
  to 
  white. 
  Some 
  of 
  the 
  

   explosions 
  were 
  probably 
  caused 
  by 
  rapidly 
  generated 
  steam, 
  but 
  

   others 
  were 
  probably 
  the 
  result 
  of 
  combustion 
  of 
  hydrocarbon 
  gases 
  

   distilled 
  from 
  the 
  inundated 
  vegetation. 
  The 
  smell 
  of 
  marsh 
  gas 
  was 
  

   distinct 
  in 
  the 
  hollows 
  near 
  the 
  lava. 
  Explosion 
  craters 
  10 
  feet 
  or 
  

   so 
  across 
  and 
  a 
  couple 
  of 
  feet 
  deep 
  were 
  observed 
  up 
  to 
  several 
  

   hundred 
  feet 
  beyond 
  the 
  margin 
  of 
  the 
  flow. 
  These 
  contained 
  no 
  new 
  

   lava, 
  nor 
  any 
  evidence 
  of 
  heating 
  or 
  alteration, 
  and 
  must 
  have 
  re- 
  

   sulted 
  from 
  the 
  migration 
  of 
  steam 
  or 
  explosive 
  gases 
  through 
  lava 
  

   tubes 
  and 
  other 
  openings 
  in 
  the 
  underlying 
  older 
  lava. 
  

  

  The 
  lava 
  advanced 
  at 
  a 
  speed 
  estimated 
  as 
  300 
  to 
  500 
  feet 
  an 
  hour, 
  

   and 
  the 
  flow 
  was 
  also 
  spreading 
  laterally, 
  but 
  at 
  a 
  much 
  slower 
  rate. 
  

   The 
  movement 
  of 
  the 
  edges 
  of 
  the 
  flow 
  could 
  be 
  observed 
  at 
  much 
  

   closer 
  quarters 
  than 
  could 
  that 
  of 
  the 
  flow 
  front. 
  "The 
  lateral 
  ad- 
  

   vance 
  was 
  made 
  by 
  yellow-hot 
  lava 
  in 
  small 
  amount 
  which 
  oozed 
  

   from 
  the 
  loose 
  steep 
  wall 
  in 
  a 
  highly 
  fluid 
  condition. 
  It 
  was 
  ap- 
  

   parently 
  of 
  such 
  low 
  viscosity 
  solely 
  on 
  the 
  strength 
  of 
  its 
  great 
  heat. 
  

   I 
  was 
  unable 
  to 
  detect 
  any 
  effervescence 
  or 
  other 
  indication 
  of 
  escaping 
  

   gas 
  * 
  * 
  *. 
  After 
  2 
  or 
  3 
  seconds 
  the 
  fluid 
  material 
  very 
  abruptly 
  

   lost 
  its 
  high 
  mobility 
  and 
  became 
  friable, 
  forming 
  fragments 
  that 
  

   rolled 
  down 
  the 
  steep, 
  rough 
  flank. 
  During 
  the 
  next 
  4 
  or 
  5 
  seconds 
  

   * 
  * 
  * 
  the 
  fragments 
  still 
  remained 
  soft 
  enough 
  so 
  as 
  not 
  to 
  make 
  

   any 
  appreciable 
  sound, 
  yet 
  of 
  such 
  a 
  consistency 
  that 
  the 
  descending 
  

   pieces 
  fragmented 
  as 
  they 
  bumped 
  down 
  the 
  slope. 
  Then 
  the 
  frag- 
  

   ments 
  cooled 
  and 
  hardened 
  to 
  the 
  point 
  that 
  the 
  characteristic 
  clinking 
  

   sound 
  was 
  made, 
  and 
  at 
  this 
  point 
  the 
  yellow-orange 
  glow 
  was 
  gone, 
  

   the 
  fragments 
  being 
  quite 
  red 
  in 
  color 
  with 
  grayed 
  and 
  darkened 
  

   edges 
  and 
  projections." 
  12 
  

  

  u 
  Schulz, 
  P. 
  B., 
  letter 
  of 
  June 
  11. 
  1942. 
  

  

  