Page 249 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

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231 Bouguer correction it ee eleva- the to anom- formula: meters). reflects has sea a above profile Fig. 8.10. The stations (the free the abrupt Bouguer in result changes. gen- is sense,

Gravity Anomalies FIGURE 8.10 applied to the free ai in Fig. 8.7. thus: is surface of m 9 mGal 1 about Bouguer gravity the to according in (h anomaly anomaly, however, excess gravity air free illustrated in anomalies. For 1) anomaly air free from removed to due anomaly, the correction; excesses Mass negative sea, gravity the strictest the

pre
sea level every adds simpte gravity Bouguer of mass the the been air 3) cause by In 8.9b).
“aes above about point anomaly Bouguer effect to profile gravity than has free Bouguer anomaly. covered
are Datum Mass Deficiency (0.0419)(2.67g/cm*)h the h The applied Jess the deficiencies (Fig.
f a lars Xx h for of the of level the air areas
f i 2 ft é Level areas that, observation correction, gravity mGal/m) the surface. gravity always sea in by free _In water
Anomaly ra . x . yA ‘Net Stations os tg Sea correction for = »Gal/m) illustrates the air free (0.112 anomaly, the Corrections Bouguer properties is anomaly above changes removed the anomalies; mass Sea the of

Bouguer Anomaly standard in m. The increased gravity. computed is the free mass additional land). (on would illustrate the level, attraction 2) changes, therefore in changes measured on
; — x 0.0419ph (0.112 below standard the — below correction, removing most a general mass been than at surface
Air equation the from Ag,, = gravity Bouguer yield of the Short-wavelength smoother
ae Free Bouguer BC = mass Using Agy air distribution therefore three Bouguer have gravity Gravity Anomaly the

The
where is h the tion, observed land on aly Like changes in an had datum level 8.7) (Fig. profiles two sea above approximate anomaly). air topographic is anomaly positive Bouguer erally

Sar

(fed) Apewouy AyAesy)

8.9a), (Fig. the of be must as taken
higher gravity relative to Bouguer Aopography of sea water (1.03 to the water depth (h,). level sea effect the (p) slab infinite commonly

results in mass of mountains datum. the level a sea thickness (h) equal to the station's elevation. ; Station Sea Lev 3 “al glem 2.67 = land, the reduction density (p) is On thickness of the infinite slab is equal to the station elevation between that g/cm’) is the difference thickness of the slab is equal above regions For subtracting from results anomaly: BC

Isostasy extra excess mass above for the slab of density (p). with Level Datum Sea fi] Station —p, Rock values.a) (2.67 g/cm’). The Land on Anomaly (Ag) anomaly gravity air free Ag; = Agp the correction, The density). (Figs. of granite

and Standard Bouguer correction +2.67 g/cm*. The the Bouguer density
Gravity Lowg Bouguer correction. a) The level. b) To account Land Sea Vee. Infinite sinh (h). b) At sea. the reduction density (— 1.64 Gravity Bouguer gravity from (BC) the reduction (the typical

Chapter8 a 8.8 FIGURE near sea areas correction assumes an infinite On a) ) At b) a 8.9 FIGURE commonly taken as g/cm’) and underlying rock Bouguer simple the slab infinite determine To assumed g/cm’, a 2.67