Science Olympiad Dynamic Planet Practice Test

What is the name of the fastest seismic wave that compresses and expands the ground?

1. S wave

2. P wave

3. Surface wave

4. Rayleigh wave

The correct answer is: P wave

The fastest seismic wave is known as a P wave, or primary wave. P waves are classified as compressional waves, which means that they cause the ground to compress and expand as they travel through it. This type of wave is the first to be detected by seismographs during an earthquake due to its high speed, traveling at speeds of about 6,000 meters per second in the Earth's crust. Unlike S waves, which are secondary waves that move slower and only travel through solids, P waves can travel through liquids and gases as well as solids. This ability to propagate through different media is significant for understanding the Earth's internal structure, as variations in wave speed can provide insights into the material properties of the Earth's layers. Surface waves, like Rayleigh waves, move along the Earth's surface and typically arrive after P and S waves. They are often associated with the greatest damage during an earthquake due to their larger amplitudes and longer duration, but they are not faster than the P waves. Thus, recognizing the distinction between these types of seismic waves is essential for grasping the mechanics of earthquake propagation and the associated effects on the Earth's surface.