Earthquakes are one of the most mysterious and terrifying natural disasters. While we have some idea of ​​when the big ones might happen, others can happen seemingly out of nowhere, bulldozer cities and creating secondary disasters such as fires, landslides and tsunami. Climate change is causing an increase in other natural disasters, such as wildfires and hurricanes. That would be fine earthquake more frequent too?
The largest and most dangerous type of earthquake is a tectonic earthquake. These earthquakes occur because of tectonic plates, the massive plates of rock that make up the Earth bark and upper mantle. Heat emanating from deep within the planet causes these plates to move on average half an inch (1.5 centimeters) per year, by which they rub against each other. The pressure builds up in these areas until it reaches a breaking point where the plates suddenly move and release the energy that causes an earthquake.
Unlike other disasters, it’s almost impossible to predict when an earthquake occurs, making planned evacuations almost impossible.
Unfortunately, climate change could cause tremors closer together and with greater intensity, experts told Live Science. With global warming, glaciers are melting at an increased rate. As the water from the melting glacier flows from the land to the sea, the land that sat beneath it rises, he said John Cassidyan earthquake seismologist from the Geological Survey of Canada and the University of Victoria.
It’s the same principle as when a child pushes a pool noodle under the surface and then lets it go: The noodle stays down as long as there is pressure from above, but once that pressure is released, it rises back up. When that happens, the pressure differences can cause previously dormant faults to suddenly disappear and cause earthquakes, Cassidy told Live Science.
Related: How big is the largest possible earthquake?
More worrisome than earthquakes from melting glaciers are those that could be caused by sea level rise. As sea levels rise, the pressure underwater on the seafloor also rises, he said Marco Bohnhoff, a geophysicist from the GFZ Helmholtz Center Potsdam and the Free University Berlin in Germany. As water pressure surges, pressure on fault lines near the coast will also increase.
“Several earthquakes are in the late seismic cycle,” Bohnhoff told Live Science, including earthquakes that are expected to occur near San Francisco and Los Angeles in the next few decades. “This means that it only takes a small increase in pressure to shift the seismic clock. In many places, that could be enough to trigger an earthquake.”
Even though we stopped using it greenhouse gases it would now take up to 1,000 years for sea level rise to stop, Bohnhoff added. It predicts that the intervals between large coastal earthquakes will shorten during that time.
Because this prediction would take centuries to prove, Bohnhoff’s research is based largely on existing models. For example, scientists modeled the rise and fall of water levels in the Salton Sea, an inland body of water about 130 kilometers northeast of San Diego, over the past 1,000 years and found that when the lake was full, more earthquakes occurred along the nearby San Andreas fault.
But Cassidy isn’t sure if sea-level rise would cause enough of a change in pressure to make these giant earthquakes happen more quickly, at least in our lifetime. He stressed that when they do occur, climate change will make them more dangerous. Earthquake-triggered tsunamis will reach further inland with rising sea levels. Warmer oceans will lead to increased precipitation, increasing the risk of earthquake-triggered landslides. Rainfall will also make earthquake tremors more pronounced, as any vibrations on wet ground are far more amplified than on dry land. But again, we won’t know exactly what’s going to happen until it happens, and according to Cassidy, there’s still a lot to figure out.
“It’s an important topic and I’m sure we’ll see a lot of information in the coming months and years,” he said. “But regardless of what we’ve discovered, it’s not good news.