Is it Possible to Prepare for an Earthquake?: Crash Course Geology #15
CrashCourse
The 1960 Valdivia earthquake 0:00
In 1960, a massive earthquake shook Valdivia, Chile for ten minutes, toppling buildings and snapping electrical wires. The coastline shifted 30 feet to the west, adding roughly 1,500 football fields worth of land to the country, and the quake triggered tsunamis that struck Hawaii and Japan. It remains the biggest earthquake ever recorded by seismographs, and it raises the question of whether we can be ready for the next big one.
How earthquake size is measured 1:01
Earthquakes are measured by magnitude, the amount of energy released, on a scale with no upper limit, unlike the 1 to 5 hurricane wind scale. About 20,000 earthquakes register globally each year, but only around 15 reach magnitude 7.0, a major quake causing serious damage, and just one per year hits 8.0 or higher, strong enough to destroy communities. Magnitude relates to the size of the fault, the fracture in the crust that breaks. The San Andreas fault in California is nearly 1,300 kilometers long but only 16 to 19 kilometers deep, so quakes there are unlikely to exceed magnitude 8.3. The Valdivia quake, by contrast, broke a shallow fault at least 1,000 kilometers long and up to 200 kilometers wide, producing a magnitude of 9.5. The biggest quakes happen at megathrust faults, where one tectonic plate slides beneath another, as in the Himalayas or the Cascadia subduction zone off the Pacific Northwest, which has produced at least seven major earthquakes in the last 3,500 years, roughly every 246 years, with the most recent around 1700 CE.
Building for the shaking 5:00
Earthquakes cannot be stopped or precisely predicted, but preparation matters, starting with infrastructure, since seismologists say buildings kill people, not earthquakes themselves. Flexible steel structures absorb shaking better than rigid stone or concrete, a practice called seismic design. Tokyo uses seismic isolation, decoupling buildings from their foundations with rubber bearings, and links its high speed rail to an early warning system that halts trains automatically. Preparedness often depends on economic resources, as shown by the 2004 Sumatra earthquake and tsunami that killed at least 226,000 people, hitting low income communities hardest. A 2015 report on the Cascadia subduction zone found it lacked an early warning system and had many unprepared buildings, though Oregon, Washington, and Seattle have since made improvements, including the Shake Alert system and resilience hubs.
What individuals can do 9:31
People can learn their local seismic risk, make evacuation and communication plans, and build emergency kits using resources like ready.gov. During a quake, the guidance is drop or lock, cover, hold on. Chile's seismic culture, built since 1960, shows how community preparedness and volunteerism help, as seen after the 2010 magnitude 8.8 earthquake when many relied on their own shelter plans rather than government shelters. Citizens can also push governments to invest in better infrastructure, aiming to understand risks, build community, and prepare realistically rather than panic.
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