General Contractor Practice Exam

What are the primary motions involved when an earthquake occurs?

1. Horizontal and diagonal

2. Rotational and oscillatory

3. Lateral and vertical

4. Translational and compressional

The correct answer is: Lateral and vertical

When an earthquake occurs, the primary motions involved are typically lateral and vertical movements of the Earth's crust. These movements occur as seismic waves travel through the ground, causing shifts and displacements along faults. Lateral motion refers to the horizontal displacement that can occur as tectonic plates slide past one another, leading to significant ground shaking. This lateral movement can result in the destruction of structures and changes in the landscape. Vertical motion, on the other hand, involves the up and down movement of the earth's surface, which can happen during the rupture of the fault or as a result of tectonic forces acting on the earth's crust. The combination of these lateral and vertical motions contributes to the overall impact of an earthquake, influencing the damage caused and the behaviors of buildings and infrastructure during seismic events. The other options do not fully encompass the primary actions observed during an earthquake. Horizontal and diagonal motions do not accurately describe the specific types of seismic wave movements. Similarly, while rotational and oscillatory motions might be present in some contexts, they are not the main descriptors of earthquake movements. Lastly, translational and compressional motions pertain more to stress and strain in the materials and are not as representative of ground movement during seismic activity.