Why do earthquakes happen?

Answer: Tectonic plates move and shift

Tectonic plates move and shift ✓ — Correct! Earth's crust is broken into large pieces called tectonic plates that float on the semi-molten mantle below. These plates constantly move very slowly. When they grind against each other, get stuck, then suddenly slip, the stored energy is released as seismic waves - that's an earthquake! Most occur at plate boundaries.

Underground explosions occur — Wrong. While underground explosions (like nuclear tests) can cause minor tremors, natural earthquakes are caused by tectonic plate movements, not explosions. The energy comes from the slow buildup of stress along fault lines.

Moon's gravity creates crust waves — Wrong. The Moon's gravity causes ocean tides, not earthquakes. Earth's solid crust doesn't flex like water does. Earthquakes come from mantle convection driving tectonic plates—completely internal forces, no lunar influence!