Seismological activity is the study of earthquakes and TREMORS, which are vibrations in the Earth's surface caused by seismic waves. TREMORS are a common form of seismological activity, and they are usually caused by the movement of tectonic plates or volcanic eruptions. TREMORS can range from mild shaking to more intense shaking that can cause damage to buildings and other structures. Seismologists use various instruments to measure and monitor TREMORS and other seismic activity.