﻿86 
  OLDHAM: 
  GREAT 
  EARTHQUAKE 
  OF 
  1897. 
  

  

  so 
  generally 
  accepted 
  and 
  repeated 
  in 
  subsequent 
  memoirs 
  and 
  

   textbooks 
  that 
  it 
  might 
  seem 
  unnecessary 
  to 
  reproduce 
  it 
  here. 
  

   This 
  will, 
  however, 
  be 
  done 
  briefly, 
  in 
  order 
  that 
  the 
  additions 
  to 
  our 
  

   knowledge, 
  consequent 
  on 
  the 
  effects 
  of 
  the 
  last 
  earthquake, 
  may 
  be 
  

   more 
  clearly 
  understood, 
  and 
  the- 
  repetition 
  will 
  besides 
  enable 
  me 
  

   to 
  bring 
  out 
  more 
  clearly 
  the 
  fact 
  that 
  the 
  fissures, 
  which 
  are 
  formed 
  

   by, 
  or 
  at 
  any 
  rate 
  are 
  observed 
  after, 
  a 
  great 
  earthquake, 
  belong 
  to 
  

   two 
  distinct 
  types, 
  a 
  distinction 
  which 
  does 
  not 
  seem 
  to 
  have 
  been 
  

   generally 
  recognised 
  and 
  sufficiently 
  emphasised 
  before 
  now. 
  

  

  One 
  class 
  of 
  fissures 
  comprises 
  those 
  superficial 
  ones 
  caused 
  by 
  

   the 
  disturbance 
  of 
  the 
  surface 
  soil, 
  or 
  occasionally 
  of 
  solid 
  rock. 
  These 
  

   fissures 
  probably 
  start 
  at 
  the 
  surface 
  and 
  penetrate 
  down 
  to 
  the 
  

   depth, 
  whatever 
  it 
  maybe, 
  that 
  they 
  reach. 
  They 
  are 
  a 
  result, 
  more 
  

   or 
  less 
  indirect, 
  of 
  the 
  wave 
  motion, 
  which 
  has 
  been 
  set 
  up 
  elsewhere 
  

   and 
  travelled 
  to 
  the 
  place 
  where 
  the 
  fissures 
  are 
  formed. 
  The 
  

   other 
  class 
  is 
  of 
  deep 
  seated 
  origin, 
  and 
  when 
  a 
  fissure 
  of 
  this 
  class, 
  

   which 
  I 
  propose 
  to 
  distinguish 
  by 
  the 
  name 
  of 
  fracture, 
  appears 
  at 
  

   the 
  surface, 
  it 
  may 
  be 
  taken 
  to 
  have 
  been 
  propagated 
  upwards 
  from 
  

   below. 
  So 
  far 
  from 
  being 
  a 
  result 
  of 
  the 
  wave 
  motion, 
  fissures 
  of 
  

   this 
  class 
  must 
  be 
  regarded 
  as 
  a 
  cause, 
  and 
  as 
  surface 
  manifestations 
  

   of 
  the 
  deeper 
  seated 
  fracture 
  by 
  whose 
  formation 
  the 
  wave 
  motion 
  

   was 
  originated. 
  In 
  their 
  immediate 
  vicinity 
  there 
  will 
  usually 
  be 
  

   found 
  indications 
  of 
  an 
  abnormal 
  violence 
  of 
  shock, 
  which 
  falls 
  off 
  

   rapidly 
  on 
  either 
  side, 
  while 
  in 
  the 
  case 
  of 
  fissures 
  of 
  the 
  first 
  class 
  no 
  

   such 
  local 
  excess 
  of 
  violence 
  will 
  be 
  noticed. 
  Only 
  those 
  fissures 
  

   which 
  fall 
  into 
  the 
  first 
  class 
  will 
  be 
  noticed 
  here, 
  a 
  discussion 
  

   of 
  those 
  belonging 
  to 
  the 
  second 
  will 
  be 
  found 
  in 
  Chapter 
  IX. 
  1 
  

  

  • 
  As 
  an 
  instance 
  of 
  what 
  I 
  believe 
  to 
  be 
  a 
  confusion 
  of 
  these 
  two 
  types 
  of 
  fissures, 
  1 
  may 
  

   quote 
  Dr. 
  J. 
  F. 
  Julius 
  Schmidt's 
  account 
  of 
  the 
  Vostizzia 
  earthquake 
  of 
  26th 
  December"'i86i 
  . 
  

   (Studien 
  uber 
  Erdbeben, 
  2nd 
  ed., 
  Leipzig, 
  1879, 
  p. 
  68.) 
  In 
  the 
  description 
  and 
  map 
  (plate 
  IV), 
  

   a 
  great 
  fissure 
  is 
  shown 
  running 
  along 
  the 
  foot 
  of 
  the 
  hills 
  for 
  about 
  three 
  miles, 
  and 
  is 
  said 
  

   to 
  have 
  been 
  ncarked 
  by 
  a 
  change 
  of 
  level 
  of 
  the 
  opposite 
  sides 
  to 
  the 
  extent 
  of 
  6 
  feet 
  or 
  more. 
  

   Besides 
  this 
  number 
  of 
  smaller 
  and 
  more 
  irregular 
  fissures, 
  accompanied 
  by 
  sand 
  vents 
  are 
  

   described 
  as 
  occurring 
  in 
  the 
  alluvium 
  near 
  the 
  sea 
  shore. 
  Dr. 
  Schmidt 
  attributes 
  all 
  to 
  the 
  

   same 
  cause 
  a 
  displacement 
  of 
  the 
  alluvial 
  deposits, 
  but 
  after 
  a 
  careful 
  study 
  of 
  his 
  description, 
  

   I 
  find 
  it 
  difficult 
  to 
  resist 
  the 
  conclusion 
  that 
  the 
  great 
  fissure 
  represents 
  part 
  of 
  the 
  focus 
  

   of 
  the 
  earthquake, 
  and 
  is 
  in 
  fact 
  a 
  fault, 
  while 
  the 
  others 
  are 
  secondary 
  effects 
  of 
  the 
  earth- 
  

   quake 
  similar 
  to 
  those 
  treated 
  in 
  this 
  chapter. 
  

  

  ( 
  86 
  ) 
  

  

  