﻿100 
  OLDHAM 
  : 
  GREAT 
  EARTHQUAKE 
  OF 
  1897. 
  

  

  Less 
  obvious 
  of 
  explanation 
  is 
  the 
  fact, 
  which 
  appears 
  well 
  

   authenticated, 
  that 
  the 
  issue 
  of 
  sand 
  and 
  water 
  went 
  on 
  in 
  some 
  places 
  

   for 
  several 
  hours 
  after 
  the 
  earthquake 
  was 
  over. 
  In 
  the 
  case 
  of 
  the 
  

   earthquake 
  of 
  Vostizzia, 
  on 
  26th 
  December 
  1861, 
  Dr. 
  J. 
  F. 
  J. 
  Schmidt 
  

   observed 
  that 
  some 
  of 
  the 
  vents 
  then 
  formed 
  continued 
  active 
  for 
  

   two 
  hours 
  after 
  the 
  shock 
  had 
  passed, 
  but 
  the 
  activity 
  was 
  in 
  this 
  case, 
  

   due, 
  to 
  the 
  issue 
  of 
  gas, 
  smelling 
  strongly 
  of 
  sulphuretted 
  hydrogen, 
  

   the 
  product 
  of 
  decaying 
  organic 
  matter. 
  In 
  the 
  case 
  of 
  the 
  present 
  

   earthquake, 
  too, 
  some 
  of 
  the 
  reported 
  cases 
  of 
  continued 
  activity 
  of 
  

   the 
  sand 
  vents 
  were 
  due 
  to 
  the 
  deceptive 
  appearance 
  produced 
  by 
  

   the 
  rising 
  of 
  gas 
  bubbles 
  through 
  the 
  water 
  which 
  filled 
  the 
  depres- 
  

   sions 
  in 
  the 
  craters, 
  but 
  there 
  is 
  still 
  a 
  sufficient 
  residuum 
  of 
  credible 
  

   accounts 
  which 
  point 
  to 
  a 
  real 
  outflow 
  of 
  water 
  from 
  the 
  vents 
  for 
  

   some 
  hours 
  after 
  the 
  earthquake, 
  in 
  some 
  cases 
  said 
  to 
  be 
  for 
  24 
  

   hours. 
  

  

  In 
  Captain 
  Gurdon's 
  account 
  he 
  distinctly 
  says 
  that, 
  the 
  ( 
  sand 
  

   geysers 
  were 
  subsequent 
  to 
  the 
  great 
  shock 
  and 
  continued 
  for 
  quite 
  

   half 
  an 
  hour.' 
  In 
  the 
  Assam 
  Government's 
  official 
  report 
  on 
  the 
  

   earthquake, 
  it 
  is 
  said 
  that 
  at 
  Gauhati 
  the 
  bubbling 
  lasted 
  for 
  24 
  

   hours 
  ; 
  other 
  accounts 
  from 
  different 
  parts 
  of 
  Bengal, 
  which 
  it 
  is 
  

   needless 
  to 
  quote 
  in 
  detail 
  1 
  , 
  mention 
  the 
  discharge 
  as 
  continuing 
  for 
  

   12 
  or 
  24 
  hours, 
  periods 
  which 
  evidently 
  do 
  not 
  represent 
  accurate 
  

   periods 
  of 
  time, 
  but 
  may 
  be 
  interpreted 
  as 
  some 
  or 
  several 
  hours. 
  

  

  Captain 
  Gurdon's 
  more 
  moderate 
  statement 
  is, 
  however, 
  sufficient 
  

   to 
  show 
  that 
  there 
  are 
  cases 
  in 
  which 
  the 
  issue 
  of 
  sand 
  and 
  water 
  

   may 
  continue 
  for 
  a 
  longer 
  period 
  of 
  time 
  than 
  is 
  explicable 
  by 
  the 
  

   momentum 
  imparted 
  to 
  the 
  sand 
  and 
  water, 
  or 
  the 
  overlying 
  imper- 
  

   vious 
  layer, 
  by 
  the 
  earthquake 
  wave. 
  This 
  may 
  most 
  probably 
  be 
  

   explained 
  as 
  follows. 
  When 
  a 
  layer 
  of 
  clay 
  or 
  clayey 
  silt 
  begins 
  to 
  

   form 
  over 
  loose 
  sand, 
  it 
  at 
  first 
  exercises 
  but 
  little 
  pressure, 
  but 
  as 
  

   the 
  thickness 
  increases 
  by 
  successive 
  additions 
  of 
  silt, 
  the 
  pressure 
  

   on 
  the 
  underlying 
  water 
  logged 
  sand 
  increases. 
  The 
  specific 
  

   gravity 
  of 
  this 
  compact 
  silt 
  is 
  greater 
  than 
  that 
  of 
  the 
  quicksand 
  

  

  / 
  j 
  00 
  ) 
  ' 
  See 
  pp. 
  16, 
  20, 
  25, 
  and 
  Appendix 
  B. 
  

  

  