Science Olympiad Dynamic Planet Practice Test

What is the main cause of earthquakes?

1. Variations in atmospheric pressure

2. Movement along tectonic plate boundaries

3. Changes in ocean currents

4. Human activities such as mining

The correct answer is: Movement along tectonic plate boundaries

The primary cause of earthquakes is the movement along tectonic plate boundaries. Earth's lithosphere is divided into several large and rigid plates known as tectonic plates. These plates are constantly in motion due to the underlying convective currents in the mantle. When these plates interact at their boundaries, stress builds over time due to frictional resistance. Eventually, the stress exceeds the strength of the rocks, leading to a sudden release of energy in the form of seismic waves, which we experience as an earthquake. This process predominantly occurs at three types of plate boundaries: convergent, divergent, and transform boundaries. Each type of boundary results in different earthquake characteristics depending on the nature of the plate interactions. The energy released during an earthquake can be significant, causing ground shaking, surface ruptures, and even tsunamis if undersea faults are involved. This geological context underlines why movement along tectonic plate boundaries is the main cause of earthquakes, making it a foundational concept in understanding seismic activity.