Page 165 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

Unmigrated and migrated Portion 1987). of the and Oil

147 of Pakistan. al., et thick- the depth ‘$€6- interfaces time to time Nankai of top pulled the

Profiles 6.11 Seismic sections recorded across a syncline the Potwar Plateau CW-13 (Lillie permission Gas Development Corporation, Pakistan. restores 6.15, Fig. in of the upper. less take corresponding the from the from event is than velocity

Reflection FIGURE in of line Published with conversion section layer; the thickness horizontal waves the profiles reflection section. The higher

on time upper the shows Seismic diagram; Seismic the is
Structures depth the On of the times 6.16 Fig. velocity. of the that time the wedge

of one == accurately, 6.14c). thickness three model in (V) side velocity pullup. Notice on accretionary
Appearance SYNCLINE ee ae thes ect o eee. rtaiee ise Fe ee eee Sia see Ss BSG Seer ekg eee known (Fig. the times actually is The higher left the to as pullup. velocity horizontal nearly the

FOCUS tgs! hE Vente eth cftoye ma BER Rate ae Rete Sue are velocities perspective proper about appears 13 middle the layer Changes Velocity and (V,) of lower interfaces beneath referred is show 6.17a) appears however, because

BURIED (Fig. 6.14b). If nesses their to middle layer suggests tion Lateral layers below the to travel of reflections shift Trough (Fig. basement oceanic left, the to up

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of (3) shows on a the diffraction, Seismic from: normal ridge seismic times of move has are section
Profiles Seismic expression line focused hyperbolic diffraction 6.12d). resulting 2) mid-ocean on travel to layer layers time

Reflection Solid the concave-upward part of the structure raypaths results (3’). Dashed line portions of the (1,2) produce crossing events that, together with (Fig. surfaces and wedge; a at appear two-way appear events middle the the though a on

Seismic 6.10 buried focus syncline. results in point; a structure appear as a “bow tie.” seen be created reflections the make 6.14a, Even interval

Of FIGURE that buried (1',2') can hummocky accretionary was a that in changes Fig. in (V,). shorter
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Structural N37 Section "Bow Pe a7 28S Section Collapses Synform so ties deep-sea offsetting soon formed velocities changes time Velocity (V.) the

Model Incidence Time r en, ee, Time to Back = ‘ % bow from faults that Effects in sections. Vertical of equal on down Vertical velocity thickness,
Chapter6 Syncline YW Unmigrated pom ememememememimin, Diffraction Focus Migrated Migration pemememrmenomemimey the cures profiles thrust 1) faults 6.13). (Fig. Velocity Changes layers or up higher equal of

146 V, Normal Buried Buried 2.
a) b) ¢) d)