| 1 | """Script for examing potential tsunami amplitudes for a submarine mass failure for West Tasmania, Australia. |
|---|
| 2 | |
|---|
| 3 | Ole Nielsen and Duncan Gray, GA - 2005 and Adrian Hitchman and Jane Sexton, GA - 2006 |
|---|
| 4 | """ |
|---|
| 5 | |
|---|
| 6 | #-------------------------------------------------------------------------------# Import necessary modules |
|---|
| 7 | #------------------------------------------------------------------------------- |
|---|
| 8 | |
|---|
| 9 | # Standard modules |
|---|
| 10 | import os |
|---|
| 11 | import time |
|---|
| 12 | |
|---|
| 13 | from pylab import * |
|---|
| 14 | ion() |
|---|
| 15 | hold(True) |
|---|
| 16 | |
|---|
| 17 | def stats_slide(depth,length,width,thickness,slope,gamma): |
|---|
| 18 | from math import sin, tan, radians, pi, sqrt, exp |
|---|
| 19 | |
|---|
| 20 | gravity = 9.8 |
|---|
| 21 | massco = 1.0 |
|---|
| 22 | dragco = 1.0 |
|---|
| 23 | psi = 0.0 |
|---|
| 24 | sint = sin(radians(slope)) |
|---|
| 25 | tant = tan(radians(slope)) |
|---|
| 26 | tanp = tan(radians(psi)) |
|---|
| 27 | |
|---|
| 28 | a0 = gravity * sint * ((gamma-1)/(gamma+massco)) * (1-(tanp/tant)) |
|---|
| 29 | ut = sqrt((gravity*depth) * (length*sint/depth) \ |
|---|
| 30 | * (pi*(gamma-1)/(2*dragco)) * (1-(tanp/tant))) |
|---|
| 31 | s0 = ut**2 / a0 |
|---|
| 32 | t0 = ut / a0 |
|---|
| 33 | |
|---|
| 34 | #calculate some parameters of the water displacement produced by the slide |
|---|
| 35 | |
|---|
| 36 | w = t0 * sqrt(gravity*depth) |
|---|
| 37 | a2D = s0 * (0.0574 - (0.0431*sint)) \ |
|---|
| 38 | * thickness/length \ |
|---|
| 39 | * ((length*sint/depth)**1.25) \ |
|---|
| 40 | * (1 - exp(-2.2*(gamma-1))) |
|---|
| 41 | a3D = a2D / (1 + (15.5*sqrt(depth/(length*sint)))) |
|---|
| 42 | |
|---|
| 43 | #scaled_amp = a3D/a2D |
|---|
| 44 | |
|---|
| 45 | return a3D, w |
|---|
| 46 | |
|---|
| 47 | def stats_slump(depth,length,width,thickness,slope,gamma): |
|---|
| 48 | from math import sin, radians, sqrt |
|---|
| 49 | |
|---|
| 50 | radius = length**2 / (8.0 * thickness) |
|---|
| 51 | massco = 1.0 |
|---|
| 52 | dphi = 0.48 |
|---|
| 53 | gravity = 9.8 |
|---|
| 54 | sint = sin(radians(slope)) |
|---|
| 55 | |
|---|
| 56 | s0 = radius * dphi / 2 |
|---|
| 57 | t0 = sqrt((radius*(gamma+massco)) / (gravity*(gamma-1))) |
|---|
| 58 | a0 = s0 / t0**2 |
|---|
| 59 | um = s0 / t0 |
|---|
| 60 | |
|---|
| 61 | #calculate some parameters of the water displacement produced by the slump |
|---|
| 62 | |
|---|
| 63 | w = t0 * sqrt(gravity*depth) |
|---|
| 64 | a2D = s0 * (0.131/sint) \ |
|---|
| 65 | * thickness/length \ |
|---|
| 66 | * (length*sint/depth)**1.25 \ |
|---|
| 67 | * (length/radius)**0.63 * dphi**0.39 \ |
|---|
| 68 | * (1.47 - (0.35*(gamma-1))) * (gamma-1) |
|---|
| 69 | a3D = a2D / (1. + (2.06*sqrt(depth/length))) |
|---|
| 70 | |
|---|
| 71 | #scaled_amp = a3D/a2D |
|---|
| 72 | |
|---|
| 73 | return a3D, w |
|---|
| 74 | |
|---|
| 75 | which_one = 'slide' |
|---|
| 76 | #which_one = 'slump' |
|---|
| 77 | par = 'depth' |
|---|
| 78 | |
|---|
| 79 | # as supplied by Cameron Mitchell end of 2007 |
|---|
| 80 | depths = range(750,2500,50) |
|---|
| 81 | lengths = [25000] |
|---|
| 82 | widths = [50000] |
|---|
| 83 | thicknesses = [400] |
|---|
| 84 | slopes = [4] |
|---|
| 85 | gammas = [1.46] |
|---|
| 86 | smftype = ['West Tas'] |
|---|
| 87 | smfdepths = [1800] |
|---|
| 88 | |
|---|
| 89 | if par == 'depth': |
|---|
| 90 | |
|---|
| 91 | for i in range(len(lengths)): |
|---|
| 92 | amp = [] |
|---|
| 93 | wavelength = [] |
|---|
| 94 | for depth in depths: |
|---|
| 95 | |
|---|
| 96 | if which_one == 'slide': |
|---|
| 97 | a, w = stats_slide(depth,lengths[i],widths[i],thicknesses[i],slopes[i],gammas[i]) |
|---|
| 98 | else: |
|---|
| 99 | a, w = stats_slump(depth,lengths[i],widths[i],thicknesses[i],slopes[i],gammas[i]) |
|---|
| 100 | |
|---|
| 101 | amp.append(a) |
|---|
| 102 | wavelength.append(w/1000.) |
|---|
| 103 | |
|---|
| 104 | figure(1) |
|---|
| 105 | plot(depths,amp) |
|---|
| 106 | xlabel('Depth (m)') |
|---|
| 107 | ylabel('amplitude (m)') |
|---|
| 108 | |
|---|
| 109 | figure(2) |
|---|
| 110 | plot(depths,wavelength) |
|---|
| 111 | xlabel('Depth (m)') |
|---|
| 112 | ylabel('wavelength (km)') |
|---|
| 113 | |
|---|
| 114 | figure(1) |
|---|
| 115 | legend(smftype) |
|---|
| 116 | savefig('depth_vs_amp') |
|---|
| 117 | |
|---|
| 118 | figure(2) |
|---|
| 119 | legend(smftype) |
|---|
| 120 | savefig('depth_vs_wavelength') |
|---|
| 121 | |
|---|
| 122 | adata = [] |
|---|
| 123 | wdata = [] |
|---|
| 124 | for i in range(len(smfdepths)): |
|---|
| 125 | if which_one == 'slide': |
|---|
| 126 | a, w = stats_slide(smfdepths[i],lengths[i],widths[i],thicknesses[i],slopes[i],gammas[i]) |
|---|
| 127 | else: |
|---|
| 128 | a, w = stats_slump(smfdepths[i],lengths[i],widths[i],thicknesses[i],slopes[i],gammas[i]) |
|---|
| 129 | adata.append(a) |
|---|
| 130 | wdata.append(w/1000.) |
|---|
| 131 | |
|---|
| 132 | figure(1) |
|---|
| 133 | plot(smfdepths,adata,'^') |
|---|
| 134 | #axis([750,2500,-0.5,6]) |
|---|
| 135 | title('Approximate amplitude for SMF off West Tasmania') |
|---|
| 136 | savefig('depth_vs_amp_data%s'%which_one) |
|---|
| 137 | figure(2) |
|---|
| 138 | plot(smfdepths,wdata,'^') |
|---|
| 139 | savefig('depth_vs_wavelength_data%s'%which_one) |
|---|
| 140 | |
|---|
| 141 | close('all') |
|---|
