# Earthquake Magnitude: Just How Big Was the Biggest Earthquake?

This week marks the anniversary of the largest earthquake ever recorded — a magnitude-9.5 earthquake that ripped along the coast of southern Chile on May 22, 1960.

The colossal quake and the powerful tsunami that followed killed more than 1,400 people and left 2 million homeless in Chile. And its devastation reached far beyond South America.

The tsunami swept across the Pacific Ocean, wreaking havoc in Hawaii, the Philippines and Japan; a day after the earthquake, walls of water up to 18 feet (5.5 meters) high rushed ashore at Honshu, Japan's main island, destroying 1,600 homes and killing 138 people.

The colossal quake was what is known as a megathrust earthquake. These giant quakes, the most powerful quakes the planet is capable of unleashing, occur along subduction zones, where one tectonic plate dives beneath another. [The 10 Biggest Earthquakes in History]

In this case, the quake was caused when a 620-mile-long (1,000 kilometers) stretch of the Nazca plate, an oceanic plate that forms a large swath of the Pacific Ocean floor, lurched deeper beneath the South American plate, producing the only 9.5-magnitude quake on record.

So just how big is a 9.5? An earthquake magnitude video, created with an animation from Nathan Becker, an oceanographer at the Pacific Tsunami Warning Center, offers a simple way to understand the vast differences between one magnitude and the next.

Essentially, each successive magnitude is 33 times larger than the last. That means a magnitude-8.0 earthquake is 33 times stronger than a 7.0, and a magnitude-9.0 earthquake is 1,089 (33 x 33) times more powerful than a 7.0 — the energy ramps up fast.

Magnitude measures

Although figuring out an earthquake's power requires lots of complicated math and lots of data, magnitude boils down to three basic factors: area, distance and friction.

"It's about the physical properties of the fault," said Paul Earle, a seismologist with the U.S. Geological Survey.

To get the magnitude, Earle told OurAmazingPlanet, you multiply the area of the fault that slipped — how much real estate moved — by the distance it moved and by the amount of friction on the fault.

Fiddling with any of those factors will change the magnitude.

Power limits

Yet some earthquakes are, by the mechanism that causes them, able to unleash far more power than others. All the most powerful earthquakes on record are so-called subduction earthquakes — the sort that happen where tectonic plates overlap.

And that's because they simply have more real estate at their disposal than earthquakes that happen in the middle of a continental plate, known as strike-slip earthquakes.

These earthquakes happen along faults that are, essentially, vertical — the San Andreas Fault is perhaps the most famous such fault in the United States.

The faults that produce strike-slip quakes plunge into the Earth's interior in a fairly straight line. That means they reach hotter, gooier geological territory — places where the rocks aren't rigid enough to make an earthquake — faster than the faults at subduction zones, which head into the Earth at an angle.

"If you go straight down, you get to the nonbrittle zone faster than if you go at an angle," Earle said. And that means strike-slip faults just don't have as much area as the angled faults at subdcution zones, and thus can't produce quakes with quite as much punch.

Yet strike-slip quakes can still cause catastrophic damage. And scientists are hard at work on designing systems that will provide a few seconds of warning when an earthquake hits, no matter what the mechanism that caused it.

### Yahoo bloggers say »

• COMMENT: Taking the talk out of the bedroom on International Women’s Day 25 minutes ago

Kirsten Han is a Singaporean blogger, journalist and filmmaker. She is also involved in the We Believe in Second Chances campaign for the abolishment of the death penalty. A social media junkie, she tweets at @kixes. The views expressed are … Continue reading →

• The story of the world's first concept car: Flickr photo of the day 6 hours ago

Today, auto shows are filled with fancy concept cars; at this week's Geneva motor show, we found enough to pack an entire slideshow -- and still had plenty leftover that didn't make the cut. It's a way for designers to express themselves and engineers to showcase future technology. But perhaps more importantly, it's a way for automakers to test the water; gauge public and media interest and, if sufficient, put together a viable plan for the company's bean-counters to consider for actual production.

• For the world's fastest supercars, 600 hp is the new normal 9 hours ago

If you look at all of the supercars just unveiled at Geneva’s Palexpo hall — the Ferrari California T, The Koenigsegg One:1, the McLaren 650S, and the Lamborghini Huracán — you will notice one thing they have in common: they’re not for you. They’re for rich people with wheelbarrows full of extra money to spend on speed and sporty/flashy good looks. The “cheapest” of them, the Ferrari, costs more than current median home price in the USA, which stands at around \$195,000, and they accelerate well beyond \$200,000 for the Lambo and McLaren, and onward into the millions, like, two or three, for the special Koenigsegg.

### Most Popular Stories »

• Tourists’ vicious fist fight on Thai Airways airline caught on video

Three passengers on board a Thai Airways plane travelling from Bangkok to Beijing last month got into the fight of their lives after an apparent argument over seats. The fist brawl between the three Mandarin-speaking passengers started when the woman … Continue reading →

• Singapore's megachurches move to export lucrative religion

By Laura Philomin SINGAPORE (Reuters) - "God is here, God is here," croons Singapore church official Sun Ho as she struts across a neon-lit stage and thousands of people in the congregation pump their hands and sing along. Kong Hee, the church's founding pastor and Sun Ho's husband, then takes the stage. Welcome to one of Asia's most profitable churches: Singapore's City Harvest. With a "prosperity gospel" that blends the spiritual and the material, City Harvest and other Pentecostal megachurches in the wealthy Asian city-state have perfected a popular and lucrative model.

• Ukraine crisis a reminder small countries must defend themselves: PM Lee

The ongoing crisis in Ukraine is a reminder that small countries must defend themselves and cannot rely solely on international treaties or the promises of others, said Prime Minister Lee Hsien Loong in his first comments on the escalating crisis.

### Featured Blogs

• Kirsten Han is a Singaporean blogger, journalist and filmmaker. She is also involved in the We Believe in Second Chances campaign for the abolishment of the death penalty. A social media junkie, she tweets at @kixes. The views expressed are … Continue reading → …

• Today, auto shows are filled with fancy concept cars; at this week's Geneva motor show, we found enough to pack an entire slideshow -- and still had plenty leftover that didn't make the cut. It's a way for designers to express themselves and engineers to showcase future technology. But perhaps more importantly, it's a way for automakers to test the water; gauge public and media interest and, if sufficient, put together a viable plan for the company's bean-counters to consider for actual …

• If you look at all of the supercars just unveiled at Geneva’s Palexpo hall — the Ferrari California T, The Koenigsegg One:1, the McLaren 650S, and the Lamborghini Huracán — you will notice one thing they have in common: they’re not for you. They’re for rich people with wheelbarrows full of extra money to spend on speed and sporty/flashy good looks. The “cheapest” of them, the Ferrari, costs more than current median home price in the USA, which stands at around \$195,000, and they accelerate well …

• Jimmy Fallon's first weeks as the new host of NBC's "The Tonight Show" has been warmly received. So when Fallon opened his show Wednesday night with a comment about wanting to buy a truck, Detroit's truck marketers fell over themselves like teen-agers hearing Kate Upton wants an invitation to prom. …

• Here are today’s top trending stories in case you missed them. Singapore's megachurches move to export lucrative religion With a "prosperity gospel" that blends the spiritual and the material, City Harvest and other Pentecostal megachurches in the wealthy Asian city-state … Continue reading → …