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Citizen seismologists track earthquakes in Haiti

When a magnitude 7.0 earthquake struck Haiti in 2010 and killed an estimated 200,000 people, there was only one working seismometer in the country. The tremor quickly overwhelmed the seismometer, an educational instrument installed in a high school, and it recorded little useful data.

Weeks passed before foreign seismic experts could travel to the disaster area, then months passed before the portable seismometers they installed recorded enough fading aftershocks to shed light on the fault. which broke.

Last August, a magnitude 7.2 earthquake struck Haiti. Conventional seismometers installed after the 2010 earthquake were not working at the time. But several small, inexpensive instruments run by citizen scientists managed to capture the seismic waves, giving researchers a much quicker view of where the Earth had sunk deep underground and demonstrating the value of mobilizing the enthusiasm of curious non-experts for science. (The earthquake’s death toll was about 2,200 people, much lower than in 2010, largely because the epicenter was in a more rural part of the country.)

“In 2021, we had this information in real time,” said Eric Calais, a geophysicist at the École Normale Supérieure in Paris who has studied Caribbean tectonics for more than 30 years. “So that’s a big difference.”

Writing in an article published Thursday in the journal Science, Dr Calais and his colleagues described what citizen science seismometers revealed about the August earthquake. About 40 miles of the same fault that caused the devastating 2010 earthquake has ruptured, but farther west. The data also revealed a few surprises, Dr Calais said: At the eastern end of this segment, the fault was not vertical, where two tectonic plates are sliding past each other. Instead, the two plates were equally close together, with the northern one sliding over the southern one.

“If we hadn’t had the distribution of the replicas, we wouldn’t have been able to fit the proper full geometry into our models,” Dr Calais said. “So our assessment of what happened would have been wrong.”

The Caribbean is sometimes an unrecognized seismic hazard zone with active volcanoes and seismic faults. “The Caribbean is its own small-scale ring of fire,” said Susan E. Hough, seismologist at the United States Geological Survey. “It’s like the Pacific Rim on a smaller scale.”

But tectonic plates are crashing together at a slower rate, and major earthquakes are happening less often. The second half of the 20th century was fairly quiet in the region. “People have gotten a little complacent about it,” Dr. Hough said. “The 2010 earthquake didn’t surprise any earthquake professional around the world, but it did surprise many people who were unaware of the scientific findings.”

Dr Hough and Dr Calais were two of the earthquake experts who visited Haiti in 2010. In the aftermath of that year’s earthquake, international organizations funded the installation of conventional seismometers, which cost dozens of thousands of dollars each, in Haiti. . When the 7.2 magnitude earthquake struck on August 14, none of Haiti’s conventional seismometers were working, although a seismometer at the US Embassy was collecting data.

“It is simply proving difficult, if not impossible, to run a conventional type of state-of-the-art seismic network in Haiti,” Dr. Hough said. “They don’t have a working power grid, for example, let alone reliable internet everywhere.”

Haiti remains politically unstable, suffers from widespread poverty and is vulnerable to natural disasters. The president, Jovenel Moïse, was assassinated the month before the August earthquake. A few days after the earthquake, a tropical storm, Grace, passed over the island.

In 2018, at a seismology conference in Malta, Dr Calais met Branden Christensen, the managing director of Raspberry Shake, a Panama-based company that combines a small, inexpensive computer called Raspberry Pi with a small, inexpensive device widely used by the oil and natural gas industries to measure tiny ground motions, creating a seismometer that costs a few hundred dollars instead of tens of thousands of dollars.

Raspberry Shake devices, smaller than a breadbox, can measure minute ground motions, albeit over a smaller frequency range than modern conventional seismometers. But they don’t need to be anchored to the ground and only require a power outlet and an internet connection.

“I immediately thought that the level of simplicity of the device was such that it would have a better chance of long-term survival in Haiti, that is to say without maintenance,” recalls Dr. Calais. He used the rest of the grant money to buy five, and together with colleagues in Haiti, he began looking for volunteers who would be willing to install one in their homes or offices. The network has since grown to around 15 devices.

Dr Calais said the data from Haiti shows that even though the Raspberry Shakes were not as capable as conventional seismometers, they nevertheless made scientifically valid measurements. “They are able to get the job done when it comes to recording even small lines,” he said.

Raspberry Shakes, however, are not immune to Haiti’s infrastructure limitations. Only one of the three near the epicenter was operational when the main quake hit last August.

The instrument closest to the epicenter was offline, as the host had dropped its internet service. But he renewed it right after feeling the jolt. “We have to accept this kind of problem,” said Dr Calais. “Internet and electricity are never a given in Haiti.”

The researchers were also able to add three Raspberry Shakes to the area, and all six measured over a thousand aftershocks that followed in the weeks that followed.

The seismic data, published online, is only part of Dr. Calais’ motivation for setting up the Raspberry Shake Network. It also aims to spread knowledge about earthquake risk among volunteers who host Raspberry Shakes and others in Haiti.

“We want to push some people in the community to do things differently,” said Steeve J. Symithe, a geophysicist at the State University of Haiti and author of the scientific paper.

Dr. Symithe, who was born in Haiti, was studying to become a civil engineer but changed fields after the 2010 earthquake, completing a doctorate at Purdue University with Dr. Calais, who was a professor there at the time.

The Raspberry Shakes, which originated from a Kickstarter project in 2016, are now installed around the world, with networks similar to those in Haiti in France, Oklahoma and Nepal. More than 1,600 devices report their data on the company’s website. “They’re popping up everywhere,” Mr. Christensen said.

With enough devices deployed, “you can start doing magical things in terms of earthquake early warning,” Christensen said. “You can start mapping and detecting earthquakes in places that people thought were aseismic or you can start mapping faults.”

Some research doesn’t even focus on earthquakes. In a paper published in Science in July 2020, scientists used data from 300 seismic stations, including 65 Raspberry Shakes, to observe a global easing in noise from trains, planes, factories and other man-made sources. following the Covid-19 pandemic.

“Without Raspberry Shake, this would have been a very difficult question to answer,” Mr. Christensen said. “The reason is that most professional-grade seismographs are set up in the mountains and in really quiet places away from humans.”