Earthquakes occur when two blocks of rock below the Earth’s surface rub against each other. Where that tension happens underground is called the hypocenter, and up above we call that the epicenter. A little rumble could be the start of bigger things to come. They are called foreshocks. The bigger shocks that come after are called the main-shocks, which might be followed by after-shocks that could come a day after or many years after. We measure the power of an Earthquake from 1-10, judging its vibrations, or magnitude, on what we call a seismograph. Hundreds of small Earthquakes happen every day, but thankfully the huge ones are rare. A 9.5 magnitude earthquake in Chile was the most powerful ever recorded, but scientists say a 10 is possible. Today we’ll focus mostly on one country, in this episode of the Infographics Show, Biggest Earthquakes Ever – What Would It Take To Destroy The USA?
We will first put into perspective Earthquakes in the USA when measured against quite recent earthquakes that were some of the largest in recorded history. Number three on the list of worst ever recorded earthquakes is one many of us old enough to remember could never forget: The 2004 Indian Ocean earthquake, sometimes called the Christmas tsunami due to when it took place and the ensuing tidal destruction. This undersea megathrust earthquake measured 9.1 – 9.3, creating tsunamis up to 100 ft high (30 meters), that quickly and devastatingly encroached coastal areas in 14 countries. 230,000–280,000 people were killed in all, from fishing villages on the western coast of Sri Lanka to touristy hotspots in Thailand’s beach towns.
Number four on the list of worst ever recorded earthquakes is Japan’s 2011 Great East Japan Earthquake. This too triggered a massive tsunami reaching up to 133 feet in height (40.5 meters). It measured 9-9.1. Casualties were fewer in number than the aforementioned disaster – 15,894 deaths – much in part due to Japan’s infrastructure and the fact that Japan had superior warning systems. Many of the countries hit by the Asian tsunami had no idea what was coming their way, as can be seen in videos of tourists in Thailand still hanging out on the beach as the tsunami approaches.
The USA is up there as having experienced one of the worst Earthquakes ever, second on the list of worst ever regarding magnitude. It was the 1964 Alaskan earthquake. It too caused great damage to structures, and generated its own tsunami, but the death toll at 139 was relatively small. Some of those deaths were as far away as California and Oregon, with loss of life not accorded to the Earthquake itself but the resultant tsunamis. While fatalities were low, the Earthquake caused wide fissures in roads and forests, destroyed many buildings, brought down bridges, and wrecked rail tracks. Had that happened in a densely populated metropolis, it could have been devastating.
Well, one of the USA’s most populated places are the cities and surrounding areas of Los Angeles and San Francisco. According to the U.S. Geological Survey, the US is destined to meet with a large Earthquake in the not too distant future, and it could well be those areas where it happens. The worst Earthquake on record in the USA did indeed happen in San Francisco, in the year 1906. The 7.9 magnitude beast occurred along 300 miles of what’s called the San Andreas Fault. This is a 750 mile long (1,200 kilometers) tectonic boundary that separates the Pacific Plate and the North American Plate. The earthquake brought the city to ruins, collapsing structures and causing widespread fires. It’s thought that about 3,000 people died and of course many more were injured. 28,000 buildings were destroyed in total, and 250,000 San Franciscans lost their homes.
This was without doubt the worst Californian earthquake in terms of causalities and destruction to buildings, but it wasn’t the most powerful. That was the Fort Tejon quake of 1857, that measured 7.9 in magnitude. Apparently only one person died when his house collapsed on him.
Lesser quakes in the area have had a much more devastating effect. In fact, outside of Alaska, Hawaii, South Carolina and Idaho, all of the USA’s worst earthquakes in terms of damage done have been in California. Some of them happened not that long ago.
Shortly after the San Francisco disaster came the Long Beach earthquake in 1933. It only had a magnitude of 6.4 but still claimed around 120 lives as people ran from collapsing buildings. The state was criticized for not having strong enough buildings to ensure safety, and as a result the state revised building codes. Some say it was a lucky escape since over 230 school buildings were destroyed, but as it happened close to 6pm, kids had already left the buildings.
Building codes were once again revised after the 1971 San Fernando earthquake. It measured 6.7 in magnitude, and caused damage to many buildings in districts of Los Angeles and beyond. It’s thought that around 58–65 people lost their lives. 49 of them were in one building alone: the Olive View Hospital in Sylmar. One of the survivors recalled some years after the incident, “There was relief when the shaking stopped, but there were still sounds of crunching…And groans.” The worrying thing is the hospital was built with earthquake resistance in mind.
Following this in 1989 and 1994, California experienced two more earthquakes resulting in loss of life. The 1989 Loma Prieta 6.9 earthquake was the first deadly earthquake to hit San Francisco Bay since the 1906 disaster, and it took 63 lives. Most of those people succumbed to a collapsed highway in Oakland. The ’94 quake hit Northridge in Southern California and measured 6.7. 60 people died, this time because their houses were structurally weak.
When scientists are asked which large cities are the mostly likely to be hit by a big earthquake in the next 20 or 30 years, one that measures over 6.7, places in California are high on the list. The world’s largest most populated city, Tokyo, is also up there. As we write this, just recently a 7.1 magnitude earthquake hit central Mexico, causing buildings to collapse in the densely populated capital of Mexico City. The full death toll is expected to be more than the 216 that has already been reported. But the question we ask today, is what would it take to destroy entire cities in the USA or even destroy the country?
First of all, scientists say what we already know from this show so far, that the worst earthquakes that could hit the USA would very likely be in Alaska or in California. The scientists say one of the worse places is the Cascadia Subduction Zone – the coast from California all the way up to Canada. They believe a 9.0 magnitude quake is very much possible, and if one happened of this size in this coastal region, it would generate huge tsunamis that would envelop the American west coast. The last one happened in 1700, and they believe we are due for another anytime in the next 400 years. According to Live Science, even though the San Andreas Fault is seen as a more dangerous area, it is thought a quake of more than 8.0 is unlikely. Former US Geological Survey scientist, Jim Berkland, who once had a book written about him called ‘The Man Who Predicts Earthquakes’, has gone on record stating the one of these regions is due for a “Big One” soon. He has been right a few times in the past.
While California has taken the headlines for a long time regarding mass destruction by earthquakes, more recent reports suggest that the Mid-West could also be an accident waiting to happen. In 1811 and 1812, a quake of 7.5 magnitude occured along the New Madrid Seismic Zone in New Madrid, Missouri. That was once thought to be a one off, but now science tells us it could happen again. This could potentially wreak havoc in Missouri, Mississippi, Illinois, Indiana, Arkansas, Kentucky, and Tennessee. A large city such as New York has suffered minor earthquakes in the past, but as it doesn’t sit on any major fault line, it’s unlikely to experience a big quake. Its biggest ever was in 1884 and measured 5.3, and some media suggest another is on its way. In fact, according to the U.S. Geological Survey, 42 of the 50 states will likely experience a damaging Earthquake in the next 50 years, but none so threatening as the one expected in the Sunshine State. Less reputable media have reported on a mega-quake that could rip apart the US and kill millions, but so far science is not backing that up.
According to The Smithsonian, the all-out destruction depicted in the movie San Andreas is way more fiction than fact. If something big goes down, the magazine says that “even the largest of California’s quakes won’t be felt by anything but seismometers on the East Coast.” A scientist did say, though, that when the big one comes, and it will, it will likely unleash destruction on many levels. It’s thought that roughly 2,000 people will die, and a lot of the damage will come from fires. Be prepared said another scientist. “Everyone should live every day like it could be the day of the Big One,” he said. “Because any day, even today, could be that day.”
So, where do you think the next big earthquake will hit? Have you ever experienced an earthquake? Let us know in the comments!