﻿160 
  DE. 
  C. 
  DAVISOtf 
  OH" 
  THE 
  PEMBKOKE 
  EARTHQUAKES 
  [May 
  1897, 
  

  

  So 
  far 
  as 
  the 
  land-areas 
  are 
  concerned 
  the 
  isoseismal 
  4 
  is 
  

   probably 
  nearly 
  accurate. 
  The 
  path 
  of 
  this 
  line 
  across 
  the 
  sea 
  is 
  of 
  

   course 
  conjectural, 
  but 
  its 
  trend 
  just 
  before 
  leaving 
  the 
  land 
  appears 
  

   to 
  indicate 
  that 
  it 
  is 
  correctly 
  drawn. 
  Assuming 
  this 
  to 
  be 
  the 
  

   case, 
  the 
  area 
  included 
  within 
  this 
  curve 
  is 
  255 
  miles 
  

   in 
  length 
  from 
  north 
  to 
  south, 
  225 
  miles 
  from 
  east 
  to 
  

   west, 
  and 
  contains 
  about 
  44,860 
  square 
  miles. 
  This 
  does 
  

   not, 
  however, 
  represent 
  the 
  whole 
  of 
  the 
  disturbed 
  area, 
  for 
  the 
  

   shock 
  was 
  plainly 
  felt 
  at 
  several 
  places 
  beyond 
  the 
  limits 
  of 
  this 
  

   isoseismal. 
  There 
  can 
  be 
  no 
  doubt 
  that 
  it 
  was 
  felt 
  at 
  Tresco 
  Abbey 
  

   in 
  the 
  Scilly 
  Isles, 
  at 
  Dorchester, 
  and 
  at 
  South 
  Littleton 
  near 
  

   Evesham, 
  the 
  distances 
  of 
  these 
  places 
  from 
  the 
  isoseismal 
  being 
  

   14, 
  12, 
  and 
  8 
  miles 
  respectively. 
  Prom 
  the 
  account 
  given 
  me 
  

   by 
  Mr. 
  J. 
  J. 
  Cole, 
  E.R.A.S., 
  I 
  believe 
  that 
  an 
  exceedingly 
  slight 
  

   tremor 
  observed 
  by 
  him 
  at 
  Sutton, 
  in 
  Surrey, 
  must 
  be 
  attributed 
  to 
  

   this 
  earthquake. 
  The 
  distance 
  of 
  Sutton 
  from 
  the 
  epicentre 
  is 
  

   about 
  200 
  miles, 
  and 
  from 
  the 
  nearest 
  point 
  of 
  the 
  isoseismal 
  4 
  

   about 
  85 
  miles. 
  Accounts 
  have 
  also 
  been 
  received 
  from 
  Ballina- 
  

   hinch 
  and 
  Milltown 
  Malbay, 
  in 
  Co. 
  Clare; 
  but, 
  from 
  the 
  great 
  

   recorded 
  intensity 
  of 
  these 
  disturbances, 
  whether 
  they 
  be 
  seismic 
  or 
  

   not, 
  I 
  have 
  no 
  hesitation 
  in 
  rejecting 
  the 
  supposition 
  of 
  any 
  con- 
  

   nexion 
  between 
  them 
  and 
  the 
  Pembroke 
  earthquake. 
  

  

  While 
  it 
  is 
  impossible 
  to 
  assign 
  definite 
  limits 
  to 
  the 
  disturbed 
  

   area, 
  there 
  can 
  thus 
  be 
  no 
  doubt 
  that 
  it 
  must 
  greatly 
  have 
  exceeded 
  

   45,000 
  square 
  miles 
  in 
  extent. 
  The 
  disturbed 
  area 
  of 
  the 
  Essex 
  

   earthquake 
  of 
  1884 
  is 
  estimated 
  b} 
  r 
  Messrs. 
  Meldola 
  and 
  White 
  at 
  

   about 
  50,000 
  square 
  miles 
  T 
  ; 
  but 
  this 
  is 
  the 
  total 
  area, 
  not 
  that 
  

   included 
  within 
  isoseismal 
  4, 
  which 
  must 
  have 
  been 
  very 
  much 
  

   smaller. 
  The 
  Pembroke 
  earthquake, 
  though 
  not 
  nearly 
  so 
  strong 
  

   near 
  the 
  epicentre, 
  must 
  therefore 
  have 
  disturbed 
  a 
  far 
  larger 
  area. 
  

   It 
  seems 
  reasonable 
  to 
  attribute 
  this 
  to 
  the 
  wide 
  distribution 
  of 
  

   older 
  and 
  harder 
  rocks 
  over 
  its 
  disturbed 
  area. 
  

  

  The 
  isoseismal 
  5 
  bounds 
  an 
  area 
  172 
  miles 
  long 
  and 
  136 
  miles 
  

   broad, 
  and 
  containing 
  about 
  18,660 
  square 
  miles. 
  The 
  centre 
  of 
  

   this 
  curve 
  is 
  about 
  2 
  J 
  miles 
  west 
  of 
  Linney 
  Head. 
  Its 
  longer 
  axis 
  

   is 
  directed 
  approximately 
  north 
  and 
  south. 
  If 
  the 
  earthquake 
  were 
  

   due 
  to 
  fault-slipping, 
  it 
  follows 
  that 
  in 
  the 
  neighbourhood 
  of 
  the 
  

   epicentre 
  the 
  direction 
  of 
  the 
  fault-line 
  must 
  be 
  north 
  

   and 
  south. 
  

  

  The 
  next 
  isoseismal 
  (intensity 
  6) 
  includes 
  the 
  whole 
  of 
  Pembroke- 
  

   shire 
  and 
  parts 
  of 
  the 
  counties 
  of 
  Caerdigan, 
  Caermarthen, 
  and 
  

   Glamorgan. 
  Only 
  the 
  eastern 
  portion 
  of 
  the 
  curve 
  can 
  be 
  drawn, 
  

   the 
  western 
  part 
  lying 
  at 
  some 
  distance 
  from 
  the 
  coast. 
  Towards 
  the 
  

   south 
  it 
  probably 
  passes 
  to 
  the 
  north 
  of 
  Lundy 
  Island, 
  but 
  it 
  would 
  

   be 
  unsafe 
  to 
  presume 
  too 
  much 
  on 
  the 
  strength 
  of 
  a 
  single 
  observa- 
  

   tion 
  at 
  that 
  place. 
  The 
  land-area 
  enclosed 
  by 
  this 
  isoseismal 
  

   contains 
  about 
  1070 
  square 
  miles. 
  

  

  1 
  'Keport 
  on 
  the 
  East 
  Anglian 
  Earthquake 
  of 
  April 
  22nd, 
  1884' 
  (1885), 
  

   p. 
  22. 
  

  

  