This page documents earthquakes based on the worst scenario earthquakes created by the USGS in these categories: Southern California, Northern California, Alaska, Hawaii, Nevada, Utah, and Global. The earthquakes are documented in order from least historic to most historic. Ranking based on potential damage.
The top 8 worst earthquakes[]
#8: Hawaii - Kau Scenario[]
The worst case scenario of a magnitude 8.0 were to strike around Pahala, the effects would be disastrous. With the island chain being volcanic, a large earthquake would most likely trigger a monstrous eruption. Coastal cliffs would likely collapse, causing a tsunami that would affect much of the eastern Pacific, causing coastal damage in Peru, Chile, Ecuador, Costa Rico, Nicaragua, El Salvador, Guatemala, Mexico, Baja California, California, Orgeon, Washington, Canada, and Alaska, and many south pacific island nations.
Most damage would be in the islands of Hawaii, with some buildings in the southern part of the main island collapsing, and 90% of the rest of the buildings being damaged. On the other islands, damage would limited to only knocked over objects, broken windows, and some cracks and fallen plaster.
Tsunami damage in Hawaii would be greater then actual earthquake itself. The wave would likely be around 1et, wiping out what would be left of coastal villages. Due to the tsunami facing the opposite direction, the other islands would only see a small wave about 10 feet, flooding low lying coastal areas.
In the other countries affected by the tsunami, the worst damage would be in Chile, Peru, Mexico, Baja California, and California. Chile would likely see a 35 foot wave, washing away houses and other small buildings. Peru would see a 28 - 31 foot wave, flattening free standing structures and washing away weak structures, such as huts and small businesses. Mexico and Baja California would both see around 20 foot waves, severely damaging coastal areas. plus, with the possible swell from a hurricane mixed in, damage could be much greater.
In California, effects would be less, with a wave around 5 to 10 feet. This would damage piers, docks, and other coastal structures. In other places, the wave would be less then 5 feet, and minor to no damage would occur.
Overall, damage would be high, with around $13 billion in damages. Deaths would be relatively low for such a catastrophic event, with around 650.
#7: Alaska - 1964 Repeat Scenario[]
The 1964 Good Friday Earthquake in Alaska caused tremendous damage, but what would happen if the earthquake repeated itself 100 years later? Well, an entire segment of the plate the Gulf of Alaska sits on would rupture, causing widespread violent shaking. Since the Gulf of Alaska is, well, a gulf, a massive tsunami would also be stirred up.
It would begin at 12:28 Pm, where the normal, quiet Sunday afternoon would suddenly be interrupted by a rattle. Just a few seconds later, the vibrations would leap to a full scale explosion of violent shaking. Car alarms roar to life, buildings crack and crumble, and the streets are lifted and dropped. As people scramble onto streets, 85% of the Anchorage Metropolitan Region is damaged or destroyed. After and a half minutes of the shaking, it comes to an abrupt stop.
People think its safe to wander around and observe the damage. during the earthquake, tsunami sirens were destroyed, therefore a warning does not blast through the city. As the wave approaches, pedestrians only have 5 minuets before a never ending wall of water 200 feet tall. Continuous small aftershocks cause the mountains to loosen further. In addition to the mountains being shaken apart, heavy rain had battered the area for 4 days, causing massive mudslides.
Then, at 12:41 PM, the massive tsunami engulfs the coast. The muddy hills quickly collapse, burying everything under the water in hundreds of feet of mud as well as causing a second mini tsunami back into pacific. At 12:55, the tsunami reaches downtown Anchorage, sweeping away all of the debris and piles of rubble left from collapsed buildings.
2 hours later, the first waves reach British Columbia, Canada, causing widespread coastal damage, especially in Vancouver, where buildings were flooded and swept away. Thanks to an early warning, only 17 people were killed in the 90 foot waves in Canada. In Washington and Oregon, 80 foot waves destroyed much of the coastal towns along the 2 states, mainly Manzanita, Oregon, and Coos Bay, Oregon. The tsunami swept through Puget Sound, flooding over 20 small islands, and tearing through downtown Seattle as a 40 foot wave. Again, just like Vancouver, a tsunami warning siren ran through the entire Puget Sound area, land and water, alerting everybody to get to higher ground. However, in Washington the tsunami proved more devastating, as 72 people were killed.
In Oregon, the tsunami washed into the Columbia River as a 60 foot wave, drowning everything within half a mile of the river. In Portland, over 5 bridges were washed away, specifically highways 5 and 205. Unfortunately, the tsunami sirens could not be activated in time, and 105 people were killed. Government Island was completely underwater, with every single building being swept away.
In other places, Mainly Hawaii, California, and Peru, the tsunami was less then 45 feet, and 152 people were killed. In total, 346 people would be killed, and damages would amount to $11 - 18 billion (2016 USD).
#6: Nevada - Las Vegas (Frenchman Mountain) Scenario[]
Another devastating earthquake possibility is a mid-ranged 6 concurring along the Frenchman Mountain Fault near Las Vegas in Nevada. Unlike Hawaii, Alaska, California, and even Washington, Nevada does not have an earthquake preparedness plan. As a result, damage was much greater. In addition to that, most of the buildings in Las Vegas are poorly built hotels and casinos which the outside walls are replaced with glass.
At 4:16 PM, west coast time, the Frenchman Mountain Fault segment released tremendous pressure. Almost instantly, the greater Las Vegas area erupted in severe shaking. Windows shattered, outside walls collapsed, powerpoles snapped, and roofs collapsed. The Las Vega International Airport sustained major damage, with 25 gates being destroyed. A plane also caught fire at the airport, and eventually exploded, causing a rampaging fire that destroyed most of Paradise, Las Vegas and Southern Las Vegas.
Since the city sits on sand, large sinkholes swallowed large portions of the city, with some places sinking as much as 35 feet in to the ground. In addition to sinkholes and fires, liquefaction resulted in isolated flooding, with Winchester, a sub-division of Las Vegas, seeing up to 3 feet of mud. The flooding happened as mud because when the water was pushed out of the ground, it mixed with sand, creating a sticky solution referred to by locals as sud.
Shaking was felt as far north as Boise, Idaho, as far south as Ensenada, Baja California, as far west as Mendocino, California, and as far east as Salido, Colorado. Damage was reported in Phoenix, where plaster fell from the roof of a bank. Power outages where reported in Death Valley, and the Hoover Dam had multiple large cracks appear, leading to slight leakage.
The earthquake also led to the collapse of the Stratosphere Tower, the tallest observation building in the US, and the tallest buildings in Nevada. Overall, at least 1,200 people would be killed, mainly tourists, and damages would total to around $33 billion (2016 USD).
#5: Global - New Madrid Scenario[]
For years, people have been worried about what would happen if another large earthquake struck the New Madrid seismic zone. They think it would be devastating, with the Mississippi River cutting the US in half, Memphis going under water, and so on and so forth. However, the effects would be much more subtle then believed.
The most likely scenario would be a 7.7 occurring near Blytheville, Arkansas. If this happened, the whole fault and 60 miles of the fault would experience violent shaking. Houses would collapse, bridges crumble, roads crack and splinter, and overpasses fall.
Many other areas, mainly to the south, would see Severe shaking. This would cause partial collapse of well built structures, widespread power outages, and other major damage. Levees in the Mississippi River would also be destroyed, leading to widespread moderate to severe flooding.
In other places, damage would be moderate or less. In places like Little Rock, Nashville, and St. Louis, objects would fall, some weakly built structures are shifted or destroyed, bridges would be cracked, and power poles would snap. Also, in places like Florida, Louisiana, and Texas, the coasts would see small waves. Overall, damage would be major in places, but would only amount to around $43 billion (2016 USD), but the death toll would be estimated at around 1,300.