Several earthquakes have shaken Los Angeles. Now fears of a catastrophic earthquake are growing. One expert makes a gloomy prediction.

Collapsed highway bridges, destroyed buildings and visible cracks throughout an entire city: The so-called Northridge earthquake shook the American metropolis of Los Angeles in 1994 with a magnitude of 6.7 on the Richter scale. 60 people died, over 9,000 were injured and the damage amounted to 20 billion US dollars (around 17.9 billion euros). Several tremors in the past few days and weeks are now causing renewed concern.

Most recently, three earthquakes with magnitudes of 3.7, 1.7 and 2.8 hit the city of Malibu just a few kilometers from Los Angeles on September 16. No one was injured. The same was true of the tremors in August (magnitude 4.4), which a t-online editor witnessed, and in June (3.4). But that doesn’t reassure residents much. Instead, they’re asking themselves: Is the mega-quake coming now?

Marco Bohnhoff, professor and geophysicist at the German Research Centre for Geosciences in Potsdam, firmly believes, as he told t-online: “A strong earthquake can occur at any time.” That would have a magnitude of at least 7 – and would therefore be stronger than the catastrophic tremors of 1994. The new earthquakes are not surprising: “They are a wake-up call,” warns the expert.

But why are these natural events no surprise? This is due to two tectonic plates, the North American and the Pacific, which collide along the Californian coast – around the clock: “This means that more and more energy is being fed into the system,” says Bohnhoff. This causes tension to build up at the plate boundaries. The longer this happens, the more certain a serious tremor is. In the specific case of California, it is only a matter of time, says the expert: “The probability that an earthquake of magnitude seven or greater will occur in California in the next 30 years is 99 percent.”

At a magnitude of 8, the earth’s crust shifts by a few meters over a length of 400 kilometers within seconds, explains the researcher. “That definitely triggers very large tremors.” The situation is particularly problematic in Los Angeles: “Los Angeles is basically built on a sedimentary basin, a depression. There are amplification effects,” says Bonhoff. However, no one can say when this will happen. The conditions for such a scenario have been created, however.

The consequences would be catastrophic, as the United States Geological Survey found in a study: Almost 1,800 people would die, 1,000 of them in Los Angeles alone. Around 50,000 people could be injured and up to a million people could lose their homes. In the worst case scenario, Southern California would be cut off from the outside world, it said. This is because the region is surrounded by mountains. If roads and highways are destroyed, it would be difficult to reach the places.

How dramatic it could really be depends on two factors, says Bohnhoff: “The key is to upgrade and improve the infrastructure to such an extent that as many buildings as possible are earthquake-proof.” The second factor is the population’s awareness of how to behave correctly in an emergency. There are corresponding exercises (earthquake drills) for this: “Test alarms are announced via cell phone and loudspeaker,” the expert continues. In addition, those affected must act according to the “duck, cover and hold” principle. Only when the situation has calmed down should they run out. “You have to practice this regularly because you have to act quickly in the event of an earthquake.”