der, 2001). Given the ability of engineers to measure all these, an emphasis on the latter is quite important in order to provide insight that would at least help in reducing earthquake intensities in the society. Particularly, the understanding of sedimentary rocks and their contribution to earthquakes intensities is necessary.
To start with, earthquake shaking starts from the rupturing fault and then continues at other distances away from the fault. Earthquake shaking intensity is supposed to decrease as the distance from the rupturing fault decreases. However, it has been observed that shaking in one site is sometimes stronger than shaking in another site. Sometimes, this shaking can be ten times higher or stronger than shaking in another site (Ammon, 1997).
Geologists have come up with information relating sedimentary rocks with earthquake shaking intensities. Geologists argue that shaking is always high in areas of softer rocks. In addition, shaking is amplified in areas of thicker sediments compared to areas of thin sediments. As it has been observed, the major reason why sedimentary rocks are associated with shaking intensities is because they are soft (Denecke & Series, 2003).
An explanation of the relationship between sedimentary rocks and earthquakes shows that seismic waves’ speed is much higher in hard rocks when compared to sedimentary rocks. This is because the latter are soft as it has been explained earlier. In areas with different rock types, waves tend to pass through harder rocks to the softer rocks, they slow down. However, in order to carry the same energy carried in the hard rocks, they tend to get bigger than before. Therefore, shaking at sites that have soft rock layers is stronger since the seismic waves tend to move slowly as shown in Figure 1 and 2 (SCEC, 2014).
The loss of life and properties associated with earthquake intensities can actually be controlled by avoiding buildings in area of soft sedimentary rocks. If this is not