What type of wave arrives after primary waves and travels at a slower speed?

The correct choice is secondary waves, which are a type of seismic wave that arrives after primary waves when an earthquake occurs. Primary waves, or P-waves, are the fastest type of seismic wave and can travel through solids, liquids, and gases. They are longitudinal waves that compress and expand the material they move through.

Secondary waves, or S-waves, follow the P-waves and travel at a slower speed. These waves are transverse, meaning they cause the ground to move perpendicular to the direction of wave propagation. Secondary waves can only travel through solids and are responsible for much of the shaking felt during earthquakes.

Understanding the distinction between these wave types is crucial in seismology, as the speed and behavior of the waves help geologists and scientists locate the epicenter of an earthquake and assess its impact. By knowing that secondary waves arrive after primary waves and have different characteristics, one can comprehend the mechanics of how seismic waves behave during an earthquake.