Earth & Environment
What Causes Earthquakes?
Earthquakes happen when stress stored along a fault is released as sudden slip, sending out seismic waves. How faults work, magnitude, and where quakes strike.
Earth & Environment
Oceans, mountains, weather and climate: how our planet works and how it is changing, explained with measurements from scientific agencies.
Earth & Environment
How Do Hurricanes Form?
Hurricanes form when thunderstorms over warm tropical oceans organize and begin to spin. The ingredients, the stages, the eye and the Saffir-Simpson wind scale.
Earth & Environment
Why Is the Ocean Salty?
Ocean salt comes from rocks on land, worn down by rain and carried to the sea by rivers, and from seafloor vents. Seawater is about 3.5% salt by weight.