geology of disney, tectonics

Could an Earthquake Destroy Disneyland?

Ah Disneyland, the Happiest Place on Earth, home of Mickey Mouse, churros, and some shaky rocks. I’ve previously gone over how Walt Disney World is located in a very sinkhole prone area and that the Epcot World Showcase Lagoon is in part a massive sinkhole, but don’t worry the Disneyland Resort has its own fun geologic hazards—the San Andreas Fault.

In recent years, there have been a few minor earthquakes felt at the Disneyland Resort. In June 2012 during the grand opening ceremony for Cars Land, there was a minor 4.1 magnitude earthquake felt in the parks, and in March 2014 a 5.1 magnitude earthquake temporarily shut down evening rides and shows, but regular operations later resumed. One of Disneyland’s very few unscheduled closures was after the 1994 magnitude 6.7 Northridge earthquake to inspect all park structures.

So what are the odds that an earthquake along the San Andreas Fault could seriously damage Disneyland? Let’s begin by first talking about the San Andreas Fault system and earthquakes.

The San Andreas Fault runs for about 800 miles through nearly the entire length of California. It is a tectonic boundary between the Pacific Plate and the North American Plate. These plates are moving in opposite directions from one another in what is known as strike-slip motion. These plates on average move about 30 millimeters per year, which is about the rate at which your fingernails grow.

Earthquakes occur along much of the extent of the San Andreas Fault system because the tectonic plates build up stresses as they try to move past one another. As you might imagine, rocks don’t want to slide past each other smoothly and steadily, so they can get hung up when trying to move past one another. Once enough stress is built up, the rocks can suddenly slip and release waves of energy that shake the crust, generating an earthquake.

The San Andreas Fault system is actually a complex series of many faults that is roughly broken into three segments: a northern segment, a central segment, and the southern segment. The northern and central segments have both produced great earthquakes of magnitude 7.8 or higher in historic times. However, the southern segment hasn’t produced a great earthquake in over 250 years, and many seismologists anticipate the next big quake along the San Andreas will be produced in this area.

This video [2:34 in video above] from the USGS and Southern California Earthquake Center shows a simulated 7.8 magnitude earthquake rupturing along the Southern San Andreas Fault. The colors show the intensity of the ground shaking, with the brighter red colors meaning more intense shaking. Notice the bright red colors propagating along the fault. However, also notice how the bright red moves toward and sits in the Los Angeles area.

This video [3:15 in video above] shows the same simulation, but with the ground view from Huntington Beach looking toward the Anaheim area. You can see the simulated surface waves rolling through this area with most of the area reaching violent shaking with likely heavy damage.

A large earthquake of this magnitude in the Los Angeles area is potentially dangerous because Los Angeles is located on top of a thick sedimentary basin with over 9,000 meters of sediment. These thick sediments would promote long periods of strong shaking in the area from the passing waves of energy from the earthquake. Based on this simulated 7.8 magnitude earthquake in Southern California, the USGS estimates that there would be 200 billion dollars caused in damages, with approximately 1,800 fatalities.

The problem with earthquakes is that they cannot be predicted or prevented. Geologists do look for clues of past earthquake ruptures known as paleoseismology to help understand recurrence intervals of earthquakes. Understanding the frequency with which past earthquakes occurred helps to understand how often big earthquakes might occur in the future.

According to a report that is known as the Third Uniform California Earthquake Rupture Forecast, there is a 75% chance that there will be at least one magnitude 7 earthquake in the Southern California region in the next 30 years.

Wo what does this mean for the House of Mouse? On a positive side, even the worst earthquake possible would not be anything like what’s shown in the movie San Andreas, that is pure fiction. But a major earthquake along the Southern San Andreas would undoubtedly cause great amounts of damage, particularly to buildings not constructed to modern earthquake codes and roadways.

Parts of Disneyland could certainly sustain minor amounts of damage. My guess is all modern Disneyland structures are built to strict earthquake codes and are designed to withstand major ground shaking events. Old and tall structures would likely be the most susceptible to damage.

So an earthquake could certainly damage Disneyland, but there’s likely no way it could totally destroy it. Large earthquakes along the San Andreas Fault are inevitable and only time will tell when and where the next big quake will occur. But for now it’s best to be prepared with a readiness plan and, might as well enjoy a future churros in the meantime.

1 thought on “Could an Earthquake Destroy Disneyland?”

  1. It’s nearly 2am and I somehow ended up down the Disney/earthquake rabbit hole. Well, that’s a way to start a Thursday.

    That said, well written and super interesting.

    Like

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