Earthquake in Mexico last week created ‘desert tsunami’ in distant cave: ScienceAlert



Last Monday, September 19, a magnitude 7.6 earthquake shook the Pacific coast of Mexico at 11:05 a.m. local time.

Five minutes later and 2,400 kilometers (1,500 miles) away, a researcher at Death Valley National Park in California noticed something strange.

Biological science technician Ambre Chaudoin was gazing into the famous limestone cavern known as Devils Hole when the usually calm entrance to the desert aquifer began to swirl and swirl.

“It’s a big earthquake, wherever it is,” Chaudoin can be heard saying in the background of his footage.

“I don’t think I’ve ever been here when there was such a big earthquake.”

Soon Chaudoin’s voice and the voices of others around her were drowned out by the crashing, sucking waves, which the US National Park Service (NPS) later announced reached more than a meter. (4 feet) high at 11:35 a.m.

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Technically, when an earthquake shakes a partially enclosed lake or body of water, it is called a seiche. But when it happens in an arid environment like Death Valley National Park, it’s colloquially referred to as a “desert tsunami.”

Although not as giant as an ocean tsunami, these waves are much larger than what is usually seen in this partially filled cavern.

“Devils Hole is a window into this vast aquifer and an unusual indicator of seismic activity around the world,” reads the NPS website.

“Major earthquakes as far away as Japan, Indonesia and Chile caused the water in Devils Hole to ‘lap’ like water in a bathtub.”

These earthquake-triggered waves have already reached up to 2 meters high, and during these extreme events the water can wash algae and diatoms out of the hole’s sunny platform.

This can be a serious problem for the hole’s isolated population of pupfish, which have been feeding and breeding on the cave shelf for over 10,000 years.

Today, the Devils Hole pupfish (Cyprinodon diabolis) are critically endangered, although numbers have recently shown signs of recovery.

Nine years ago, there were only 75 pupfish left in Devils Hole. This year, an official tally in March reached 175.

It is not yet known why the Devils Hole pupfish are suffering. Not all desert tsunamis are a fatal event for these creatures, but they are certainly a risk factor given the limited nutrients available in the 152-meter-deep (500-foot) habitat.

The waves in Devils Hole can actually help the ecosystem, cleaning the shelf of organic matter that can deplete the aquifer of oxygen over time.

“That kind of system reset,” Kevin Wilson, an NPS aquatic ecologist, told the Los Angeles Time.

But if these waves are powerful enough, they can also carry too much.

Fortunately, no dead pupfish were found after the earthquake in Mexico, but it’s unclear how much seaweed the waves washed up or how many fish eggs the splashing may have crushed.

The recent phenomenon is a good reminder that a disaster in one part of the world may very well have an impact on an ecosystem or an unrecognized species thousands of miles away.

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