Exam Name : UPSC Geo-Scientist and Geologist Exam 2019
Subject : Geophysics Paper - I
Year : 2019
Time Allowed : Three Hours
Maximum Marks : 200
1.(a) How many half-lives must elapse before the activity of a radioactive isotope decreases to 2% of its initial value? How long is this time for 14 C (carbon 14 isotope), which has a decay rate of 1.21x10-4 yr-1?
1.(b) The moment of the recent Indonesian earthquake has been estimated to be about 1.0x1023 Nm. Assume that the fault is horizontal, where slip area is 100 km wide and 1300 km long, and the shear modulus u = 3.0x1010 N/m2, calculate the average displacement on the fault.
1.(c)Discuss about the origin of the geomagnetic field.