List of top Geophysics Questions on Gravity and Magnetics

The figure below shows Bouguer gravity anomaly values (in mGal) at a grid interval of 1 km, centred on point P (r1 and r2 are radial distances from P).
The second vertical derivative at P is _________ mGal/km\(^2\) (rounded off to two decimals).
The vector field \(\mathbf{F}\) for a region is described by \(\mathbf{F} = a r^n \hat{r}\) \((r\neq 0)\), where \(a\) is a non-zero constant and \(r\) is the radial distance from the source. For what value(s) of \(n\), \(\mathbf{F}\) becomes both solenoidal and irrotational?
\(\Delta T = [\Delta T_1, \Delta T_2, \ldots, \Delta T_{19}, \Delta T_{20}]\), and \(\Delta T_u = [\Delta T_{u1}, \Delta T_{u2}, \ldots, \Delta T_{u19}, \Delta T_{u20}]\) denote the magnetic data observed at heights 0 km and 5 km, respectively, along a profile of length 100 km. What is the maximum attenuation at a height of 5 km?
[Use wave number in radian/km].
\(\Delta B_z\) represents the maximum vertical magnetic anomaly along a profile due to a horizontal cylinder with susceptibility contrast \((\Delta k)\), and radius \((r)\) at a depth \((z)\) below the Earth's surface. Which combination(s) of \(\Delta k\), \(r\), and \(z\) labelled as P, Q, R and S given below, produces/produce the same \(\Delta B_z\)?
(P) \(\Delta k=0.02\), \(r=100\ m\), and \(z=200\ m\)
(Q) \(\Delta k=0.01\), \(r=80\ m\), and \(z=160\ m\)
(R) \(\Delta k=0.005\), \(r=200\ m\), and \(z=400\ m\)
(S) \(\Delta k=0.02\), \(r=150\ m\), and \(z=300\ m\)
If \(F\) represents the Earth's total magnetic field corresponding to its dipole source only, then the increase in \(F\) from 0\(^\circ\) to 60\(^\circ\) N magnetic latitude is __________ % (rounded off to one decimal place).
If \(g_{FA}\) and \(g_{BA}\) respectively denote the free-air and Bouguer gravity anomalies over a fully compensated mountain, then which one of the following is CORRECT in case of Airy-isostacy?
Analytic signal, \(A(\theta)\), for \(f(\theta) = \cos\theta\) is equal to
A land magnetic survey was carried out along a profile length of 500 m with an inter-station spacing of 5 m over a buried ore body. The optimum width of the body that can be best resolved is __________ m (answer in integer).
What happens to the magnetic susceptibility (\(k\)) and remanent magnetization (\(I_r\)), when the molten rock undergoes rapid cooling?