FAQ

Earthquakes are caused by the sudden release of energy in the Earth's crust, usually along fault lines where tectonic plates meet. As plates push against each other, stress builds up until the rock breaks, releasing waves of energy that we feel as shaking.

Magnitude is most commonly measured using the Moment Magnitude Scale (Mw), which replaced the older Richter Scale. It measures the total energy released by an earthquake based on the area of the fault that slipped, the amount of slip, and the rigidity of the rocks.

Magnitude measures the energy released at the earthquake's source (a single number). Intensity measures the shaking and damage at a specific location (varies by distance from epicenter). A single earthquake has one magnitude but many different intensity values.

Earthquakes occur at depths from near the surface down to about 700 km (435 miles). Shallow earthquakes (0-70 km) cause the most damage. Intermediate (70-300 km) and deep (300-700 km) earthquakes are felt over wider areas but typically cause less surface damage.

About 500,000 detectable earthquakes occur each year worldwide. Of these, roughly 100,000 can be felt, and about 100 cause damage. On average, one M8+ earthquake occurs per year, 15-20 M7+, and about 150 M6+ earthquakes.

The Ring of Fire is a 40,000 km horseshoe-shaped area around the Pacific Ocean where about 90% of the world's earthquakes occur. It's home to 75% of the world's active volcanoes and follows the boundaries of several major tectonic plates.

Currently, earthquakes cannot be accurately predicted. Scientists can calculate probabilities of future earthquakes based on historical data and fault monitoring, but pinpointing the exact time and location of a specific earthquake remains impossible.

Drop, Cover, and Hold On. Drop to your hands and knees, take cover under a sturdy table or desk, and hold on until the shaking stops. Stay indoors if you are inside. If outdoors, stay away from buildings, streetlights, and utility wires.