Question

Exercise : Volcano Shape The purpose of this exercise is to compare the slope of two volcanoes, Hawaii and Mt. St. Helens Hawai: The Hawaiian volcanoes are shield volcanoes, though some cinder cones are present as well. The very low viscosity of mafic/basaltic magma that cools to form the Hawaiian shield volcanoes produces very gentle or shallow slopes. This is a primary characteristic of shield volcanoes. So, let's try to get an impression of just how low the slopes of a shield volcano are. The slope of a land surface can be determined from the information available on a 1000 topographic map (figure 8). The elevation of Mauna Loa is 4,169 meters. Figure 8. Topographic map of Mauna Loa. Contours are in feet. Relief is the difference in elevation from the highest point to the lowest point. What is the relief (in meters) along the line A-A? Note that the contour intervals are 1000 ft. 1. 2. Measure the horizontal distance from Mauna Loa (highest peak) to the eastern coastline along the line A-A' using the scale provided. What is the horizontal distance in km? 3. The gradient or slope is simply the rise (relief) divided by the run (horizontal distance). What is the slope in meters/km? EES GEO 211-Physical Geology

Answer 1

1. here highest elevation is 130000 ft and lowest elevation is 0 ft( along the coastline).

        so the relief is (13,0000-0) ft = 13,0000 ft = 39624 meters [ 1 ft = 0.3048 meters]

2. horizontal distance from Mauna Loa( highest peak= 13,0000 ft) to the eastern coastline along the line A-A' is 81.29 km.

how to measure it:(I am giving you instructions because mine and your value won't match as I have calculated from this given picture, though the aspect ratio will be same I hope, unless there is minimum distortion occurred while taking the picture)

take a ruler and place it on the line A-A', measure the distance (in centimeter) between 13,0000 ft contour line and the coast line, suppose the length is X c.m

now place the ruler on the scale line, and measure how much centimeter it takes to cover 30km. suppose the length is Y cm.

so, in map Y cm = 30km in real

      in map X cm = (30/Y)* X      km in real.

3. Slope / gradient= relief/ horizontal distance = 39624/ 81.29 = 487.44 meters/km...