Page 169 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists
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151                                                                                   s
                      (s)  aus  janes,  Aep,-omy
                                                                      (un)  yideq
          Profiles   0.0   eq   9       9      wr                       S      3   6.0            AAPG
                                               S
                                                                        .y
                                        o
                                N
          Reflection
          on   Section   :                                                                          with  permission  of  the
          Structures                                                             Sekine   a   aS  i   R.  Chambers,  Imaging  beneath  complex structure,  American


          of     megs   EG                                                 8   NS Shy   eS   <   ;   eis   Re   ROE  Migrated  time  and migrated  depth  sections  in  a  region  of drastic  difference  in  layer
          Appearance   Migrated Time   f                                     aa   oe   Senta   Sok   5   RR   =  ae  ae  26-39,  ©  1983,  Redrawn   Opahone  att   Ue




                 oo
                  Z

                                                                               Seaee   ere,   Sse     SEONG        -
                 eee                                                                              K.  Larner,  B.  Gibson, and   i
                                    t                                      ely                      oo   IRA
                 —eee se   Low Velocity   Layer   Velocity   High   Layer   Relatively   Thin   Relativ   Thick   a   6.15   FIGURE   velocity. From   ee

















             Effects  of vertical changes   (a),  having   in   upper  layer,   two-way  travel   dips   of   time   the   anti-   with   raypath   event   in   primary



         Profiles   (b).  Proper  depth  conversion   the  true  thickness.   actually   encounter   anticline   unmigrated   outside   separating   6.18b).  The   the   6.18c).   raypath-bending   of  faulting  of  hori-   migration,   distortion   takes   lower   shown   is   advantages   Only

         Reflection   6.14  velocity.  The  middle  layer  twice  the  velocity  of  the  occupies  only half  the   basement   they   when   the   below   an   from   interface   (V,;  Fig.   below  interface   (Fig.   the   standard  shows   still   which   the   that   effects   following   1)



         Seismic   FIGURE   in   in   time   (c)  restores        the   (Fig.  6.17b).   Law,   placed   on   originating   the   cross   layer   events   for   interpretation   a   conversion   migration,   notice   bending   the   problems.

         Of     (uy)  yideq    (s)  ew  JPABLL   (um)  yideq      that   wedge   Snell’s   effect)   they   velocity   horizontal   horizontal   account   of   results   6.19d;   raypath   have   potential
         Interpretation   > V,   Ss  2  .   9   42.0   S  2  .   38   shows   accretionary   to   interface  horizontal   bending   6.18)*Rays   (Fig.   when   higher   the   the   from   area,  crossing   sufficiently   erroneous   the  shows  A   depth   bent.   sophisticated   Fig.   in  section   faulted.   be   not   and   sections   time   and
                                 ABM -OM]
                  _
                       N
                                                   ™~
                                                        N

         Tectonic   V,                                            conversion   the   according   A   (raypath  events   pullup   downward   from   (V,)   reflections   larger   not   will   to  leading   6.19b   not   more   the   may   it   3   and   velocity,   migrated   techniques

         And   Change                                             Depth   beneath   (refract),   3.22).   velocity   refract   a   over   routines   Fig.  are  raypaths   6.19c).  A   2,   1,   geometric,   and
         Structural   Velocity          1.0s      te=0.5s                     trench.   the   region   direction   (Fig.  obliquely   overlapping   to  addition   anticline   lower  velocity   incidence   spread   migration   6.18d),  sometimes   continuous.   that   (Fig.   event   account,  produces  continuous,  suggesting   Effects   produces   unmigrated  understanding  interpretation




         6                         t;=                            filling   trench   Bending   change   shows   in   the   of   with   normal   thus   Most   (Fig.   are   that   assumption   lower   into   of   that   The
         Chapter   Model of  Vertical   Section   Section         water   the   from   Raypath   Rays   interfaces   6.8   Fig.   section,   bounds   layer   the   resulting,   are   cline   effect   zons   the   of  the   bending   more   is   Combination   model   A   6.20.   Fig.   for


         150                   Time            Depth                    3.


             a)                b)          5   c)
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