Description
For the following exercises, assume a Young’s modulus of 7 x 1010 Pa, Poisson’s ratio of 0.25, acceleration due to gravity of 9.81 ms-2, a density of the mantle of 3300 kgm-3, a density of crust (loads) of 2700 kgm-3, a density of sea water of 1035 kgm-3, and a density of sedimentary basin fill of 2400 kgm-3.
For each problem include a diagram setting up the problem (5 points), the equations that you will use (5 points), and then solve the equations (10 points). You may use a spreadsheet to conduct the calculations. Print or draft the deflected crustal profile for each question (10 points).
- Calculate the maximum deflection beneath and width of a water-filled basin surrounding an infinite line of volcanoes on an infinite (i.e., unbroken plate) with an effective elastic thickness of 20 km. The line of volcanoes constitutes a 5 km high and 50 km wide load. Use the equations for line loading from lecture 2 to calculate wo and xo.
- Next consider a broad mountain belt that can be characterized by 5 blocks, each 20 km wide that decrease in height from the hinterland to the foreland from 5 to 1 km. Assume that these sit on an infinite plate with an effective elastic thickness of 40 km. Calculate the total subsidence in a filled sedimentary basin directly in front of the shortest block. Calculate the basin width from the front of the shortest block to the zero deflection point.
