Episode Details

Daniel wants to know why Japan gets so many earthquakes while where he lives barely feels any.

The answer starts underneath his feet.

The Earth's crust is not one solid piece. It is broken into enormous sections -- like a cracked eggshell -- and they are all moving. Slowly. All the time. About as fast as your fingernails grow. Where those sections meet is where earthquakes happen. Japan lies along the boundaries of four major tectonic plates -- very few places on Earth sit at the meeting of so many.

Around the Pacific Ocean, many of Earth's most active plate boundaries are concentrated in a zone called the Ring of Fire -- a horseshoe-shaped belt roughly forty thousand kilometers long. About ninety percent of all earthquakes happen there. Japan, California, Chile, Indonesia, New Zealand -- all sitting on or near that ring. And roughly seventy-five percent of the world's active volcanoes are found there too. The same plate boundaries that cause earthquakes also cause volcanoes.

Here is how an earthquake actually happens. The plates do not glide smoothly. They lock together at the edges while the rest of each plate keeps trying to move. Pressure builds for years. Sometimes centuries. Until the stress becomes too great -- and the plates suddenly slip. That release of energy sends seismic waves through the ground in every direction. That is the earthquake.

Then Daniel asks the more important question.

Why does a powerful earthquake devastate one place while a similar one causes far less destruction somewhere else?

Because the earthquake is not what kills people. What kills people is usually buildings falling on them.

In 2011 Japan experienced a magnitude nine earthquake -- one of the most powerful ever recorded. The earthquake and tsunami that followed caused enormous destruction and nearly twenty thousand deaths. But many modern buildings survived the shaking itself remarkably well -- because Japan has spent decades designing structures specifically to withstand earthquakes. Some buildings sit on base isolators -- layered pads of rubber and steel -- that let the building slide slightly during shaking so the structure absorbs the energy instead of fighting it. Japan also has earthquake early warning systems that alert people seconds before shaking arrives. Trains stop automatically. People take cover. Seconds matter enormously when you know what to do.

An earthquake is a natural event. Whether it becomes a catastrophe depends enormously on how prepared people are.

The earthquake may be similar in size. The outcomes can be completely different.

Daniel's closing line about base isolators -- and birthday parties -- is worth staying for.

What you will find in this episode:

• Why the Earth's crust moves and where earthquakes happen
• What the Ring of Fire is and why it contains ninety percent of earthquakes
• How plate friction builds up and releases as seismic waves
• Why the same earthquake can cause completely different levels of disaster
• How earthquake-resistant buildings work -- including base isolators
• Why early warning systems save lives
• Daniel's summary: geology tells you where. Preparation tells you how bad.

Clear, important, and the kind of episode that changes how you look at every tall building you walk into.

Listen, wonder, and learn.

Find us @smilewithDaniel everywhere.