How Earthquakes Work: Illustrated Science | sisma

Science

How earthquakes work, explained visually.

01 · 6 min readPlate tectonicsEarth’s outer shell is broken into about 15 major plates of rigid lithosphere, each up to ~100 km thick, gliding over the hotter, weaker asthenosphere at 2–10 cm a year — about as fast as fingernails grow. Almost every earthquake happens where plates meet.02 · 5 min readFault typesA fault is a fracture where blocks of rock have moved past each other. How they move depends on whether the crust is being stretched, squeezed or sheared.03 · 6 min readSeismic wavesWhen a fault ruptures, energy spreads out as seismic waves. Seismometers record them in a fixed order, and the gaps between arrivals tell us where and how big the earthquake was.04 · 5 min readMagnitude vs intensityMagnitude measures the size of an earthquake at its source — one number per event. Intensity measures the shaking at a particular place, and changes with distance, depth and ground type.05 · 5 min readDepth & aftershocksEarthquakes happen from the surface down to about 700 km. Depth changes how strongly shaking reaches us, and tells us about the plates beneath.06 · 4 min readTsunamisA tsunami is a series of waves caused by the sudden displacement of a huge volume of water — most often when a megathrust earthquake lifts or drops the sea floor.07 · 4 min readPreparednessNo one can predict earthquakes, but preparation saves lives. Most injuries come from falling objects and debris, not collapsing buildings.08 · 6 min readThe Ring of FireThe Ring of Fire is a horseshoe of ocean trenches, volcanoes and faults about 40,000 km long around the edge of the Pacific Ocean: from New Zealand, Tonga and Indonesia through the Philippines, Japan and Kamchatka, across the Aleutians and Alaska, and down the Americas to the tip of Chile. About 90% of the world’s earthquakes happen along it, including most of the largest.

sisma

The Pulse of a Living Planet