﻿284 
  Jaggar 
  — 
  Lava 
  Flow 
  from 
  Mauna 
  Zoa, 
  1916. 
  

  

  time 
  of 
  rapid 
  sinking-back 
  of 
  the 
  lava 
  in 
  the 
  fissures. 
  On 
  that 
  

   day 
  Kilanea 
  suffered 
  sudden 
  and 
  cataclysmal 
  subsidence. 
  

  

  The 
  Great 
  Subsidence 
  in 
  JZciIemaumau. 
  

  

  In 
  the 
  Kilauea 
  fire 
  pit 
  during 
  the 
  month 
  preceding 
  the 
  out- 
  

   break 
  of 
  Mauna 
  Loa 
  there 
  was 
  an 
  elliptical 
  lava 
  lake 
  which 
  on 
  

   April 
  30 
  measured 
  775 
  feet 
  (236 
  m.) 
  long 
  east-west 
  by 
  665 
  feet 
  

   (203 
  m.) 
  wide 
  north-south. 
  This 
  lake 
  was 
  confined 
  by 
  an 
  annular 
  

   bench 
  of 
  overflow 
  the 
  outer 
  periphery 
  of 
  which 
  was 
  an 
  oval 
  

   1110 
  feet 
  (338-5 
  m.) 
  long 
  by 
  1000 
  feet 
  (305 
  m.) 
  wide. 
  There 
  

   were 
  two 
  islands 
  in 
  the 
  lake, 
  respectively 
  400 
  feet 
  (122 
  m.) 
  

   and 
  250 
  feet 
  (76 
  in.) 
  long 
  and 
  55 
  feet 
  (17 
  m.) 
  and 
  41 
  feet 
  

   (12*7 
  m.) 
  high. 
  These 
  islands 
  had 
  gradually 
  developed 
  during 
  

   the 
  spring 
  from 
  tilted 
  bench 
  crags 
  on 
  the 
  border 
  of 
  a 
  less 
  

   symmetrical 
  lava 
  pool 
  which 
  had 
  risen 
  and 
  surrounded 
  them. 
  

   The 
  depression 
  of 
  the 
  lake 
  on 
  April 
  30 
  below 
  the 
  rim 
  of 
  Hale- 
  

   maumau 
  pit 
  was 
  321 
  feet 
  (98 
  m.). 
  Occasionally 
  overflowing 
  

   the 
  benches, 
  the 
  lake 
  rose 
  slowly 
  in 
  May 
  so 
  that 
  the 
  depression 
  

   was 
  approximately 
  as 
  follows 
  : 
  

  

  April 
  30 
  321 
  feet 
  (98 
  m.) 
  

  

  May 
  17 
  :i00 
  " 
  (91*7 
  m.) 
  

  

  May 
  19, 
  8 
  p.m. 
  295 
  -- 
  (90 
  m.) 
  

  

  May 
  20, 
  noon 
  290 
  " 
  (88 
  4 
  m.) 
  

  

  May 
  21 
  285 
  •' 
  (86'9 
  m.) 
  

  

  May 
  23 
  2 
  70 
  " 
  (82 
  '3 
  m.) 
  

  

  May 
  24 
  2G5 
  " 
  (80*9 
  m.) 
  

  

  Analysis 
  of 
  this 
  rise 
  reveals 
  the 
  remarkable 
  fact 
  that 
  from 
  

   May 
  1 
  to 
  the 
  morning 
  of 
  May 
  19 
  the 
  average 
  rate 
  of 
  rising 
  was 
  

   less 
  than 
  one 
  foot 
  per 
  day, 
  whereas 
  beginning 
  suddenly 
  on 
  the 
  

   evening 
  of 
  May 
  19, 
  the 
  rising 
  increased 
  to 
  a 
  daily 
  average 
  of 
  

   six 
  feet 
  per 
  day 
  for 
  the 
  five 
  days 
  May 
  19-24. 
  The 
  morning 
  of 
  

   May 
  19 
  witnessed 
  the 
  high 
  explosive 
  outburst 
  of 
  Mauna 
  Loa, 
  

   and 
  May 
  24 
  represented 
  about 
  the 
  culmination 
  of 
  the 
  period 
  of 
  

   lava 
  outflow 
  on 
  Mauna 
  Loa. 
  

  

  On 
  May 
  24, 
  1916, 
  the 
  Kilauea 
  lava 
  column 
  reached 
  a 
  turn- 
  

   ing 
  point 
  and 
  thereafter 
  for 
  eleven 
  days 
  to 
  June 
  4, 
  it 
  sank, 
  

   with 
  average 
  subsidence 
  of 
  3'3 
  feet 
  (1 
  m.) 
  per 
  day. 
  The 
  

   measured 
  depression 
  below 
  the 
  3700-foot 
  (1125 
  in.) 
  contour, 
  

   the 
  rim 
  of 
  Halemaumau, 
  including 
  the 
  great 
  collapse 
  of 
  June 
  

   5-6 
  and 
  the 
  recovery 
  later, 
  are 
  shown, 
  graphically 
  on 
  fig. 
  1, 
  

   and 
  in 
  the 
  following 
  table 
  : 
  

  

  May 
  25 
  

  

  270 
  feet 
  ( 
  82*3 
  m.) 
  

  

  May 
  26 
  

  

  273 
  " 
  ( 
  83-1 
  m.) 
  

  

  May 
  27 
  

  

  278 
  " 
  ( 
  84-9 
  m.) 
  

  

  May 
  28 
  

  

  270 
  " 
  ( 
  82-3 
  m.) 
  

  

  May 
  29 
  

  

  280 
  " 
  ( 
  85-5 
  m.) 
  

  

  