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  OLDHAM: 
  GREAT 
  EARTHQUAKE 
  OF 
  1897. 
  

  

  Chapter 
  VIII.— 
  THE 
  AFTERSHOCKS. 
  

  

  The 
  study 
  of 
  the 
  aftershocks 
  of 
  earthquakes 
  is 
  one 
  to 
  which 
  

   much 
  attention 
  has 
  been 
  paid 
  of 
  late 
  years, 
  and 
  the 
  investigations 
  by 
  

   Messrs. 
  Omori 
  1 
  and 
  C. 
  Davison 
  2 
  of 
  the 
  records 
  of 
  the 
  aftershocks 
  of 
  

   the 
  oreat 
  Japanese 
  earthquake 
  of 
  1891 
  have 
  thrown 
  light 
  on 
  the 
  laws 
  

   which 
  crovern 
  their 
  gradual 
  diminution 
  in 
  number, 
  and 
  the 
  gradual 
  

   shifting 
  of 
  the 
  main 
  centre 
  of 
  seismic 
  activity. 
  

  

  In 
  India 
  there 
  is 
  no 
  regular 
  system 
  of 
  recording 
  earthquakes, 
  such 
  

   as 
  has 
  been 
  established 
  in 
  Japan, 
  but 
  one 
  of 
  the 
  first 
  steps 
  taken 
  

   after 
  the 
  great 
  earthquake 
  of 
  last 
  year 
  was 
  to 
  interest 
  as 
  large 
  a 
  

   number 
  of 
  observers 
  as 
  possible 
  in 
  keeping 
  a 
  record 
  of 
  the 
  shocks 
  

   felt 
  by 
  them. 
  Such 
  record 
  is 
  of 
  course 
  much 
  less 
  perfect 
  than 
  one 
  

   kept 
  by 
  automatic 
  instruments, 
  but 
  in 
  spite 
  of 
  this 
  drawback 
  a 
  large 
  

   number 
  of 
  valuable 
  observations 
  have 
  been 
  recorded, 
  which 
  will 
  be 
  

   published 
  in 
  a 
  separate 
  part 
  of 
  these 
  Memoirs 
  so 
  far 
  as 
  seems 
  neces- 
  

   sary. 
  At 
  present 
  the 
  time 
  has 
  not 
  come, 
  nor 
  the 
  time 
  been 
  avail- 
  

   able, 
  for 
  a 
  collation 
  and 
  discussion 
  of 
  these 
  observations, 
  but 
  a 
  brief 
  

   review 
  of 
  the 
  general 
  course 
  and 
  character 
  of 
  these 
  series 
  of 
  after- 
  

   shocks 
  may 
  be 
  given. 
  

  

  At 
  Shillong, 
  Tura, 
  and 
  all 
  other 
  places 
  within 
  the 
  epicentral 
  

   area, 
  as 
  defined 
  in 
  the 
  next 
  chapter, 
  the 
  shocks 
  felt 
  during 
  the 
  day 
  

   following 
  the 
  great 
  earthquake 
  were 
  to 
  be 
  numbered 
  by 
  hundreds. 
  

   In 
  fact 
  it 
  is 
  impossible 
  to 
  give 
  a 
  number, 
  for 
  it 
  does 
  not 
  seem 
  to 
  be 
  

   an 
  exaggeration 
  to 
  say 
  that 
  for 
  days 
  the 
  earth 
  never 
  came 
  to 
  rest, 
  but 
  

   was 
  in 
  a 
  constant 
  state 
  of 
  gentle 
  tremor, 
  interrupted 
  at 
  frequent 
  

   intervals 
  by 
  distinctly 
  sensible, 
  and 
  again 
  at 
  longer 
  ones 
  by 
  severe 
  

   shocks. 
  At 
  the 
  Bordwar 
  tea 
  estate, 
  situated 
  right 
  on 
  one 
  of 
  the 
  focal 
  

   fractures 
  which 
  extended 
  to 
  the 
  surface, 
  I 
  was 
  informed 
  that 
  for 
  a 
  week 
  

   after 
  the 
  great 
  shock 
  the 
  surface 
  of 
  a 
  glass 
  of 
  water 
  standing 
  on 
  a 
  table 
  

  

  1 
  On 
  th« 
  aftershocks 
  of 
  earthquakes 
  Jour. 
  Coll. 
  Sci. 
  Imp. 
  Univ. 
  Japan, 
  VII, 
  111-200 
  

  

  (1894). 
  

  

  2 
  On 
  the 
  distribution 
  in 
  space 
  of 
  the 
  Accessory 
  shocks 
  of 
  the 
  great 
  Japanese 
  earthquake 
  

   of 
  1891 
  : 
  Quart. 
  Jour. 
  Geol. 
  Soc. 
  LI1 
  , 
  1 
  15 
  (1897). 
  

  

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