IPA: /ˈɜːrθkweɪk/
KK: /ˈɜrθˌkwāk/
A sudden shaking of the ground caused by movements in the Earth's crust, often resulting in damage.
The earthquake caused significant damage to the buildings in the city.
Earthquake is formed from "earth" (from Old English "eorþe", meaning the ground or soil) and "quake" (from Old English "cwacian", meaning to shake or tremble). The word describes the shaking or trembling of the ground.
Think of the ground ('earth') shaking or 'trembling' ('quake') — that's what an earthquake is.