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These small, inexpensive devices help monitor Haiti’s earthquake

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These small, inexpensive devices help monitor Haiti’s earthquake

When a magnitude 7.0 earthquake struck Haiti in 2010 and killed an estimated 200,000 people, the country had only one working seismometer. The tremors quickly overwhelmed the seismometer, an education device installed in a high school, and it recorded little useful data.

Weeks passed before foreign seismologists traveled to the disaster area, and then months passed before portable seismometers were installed, which recorded enough fading aftershocks to shed light on the torn fault.

Last August, a magnitude 7.2 earthquake struck Haiti. Conventional seismometers installed after the 2010 earthquake were not working at that time. But several small, inexpensive instruments run by citizen scientists managed to capture the seismic waves, giving researchers an idea of ​​where Earth broke deep underground and the value of enlisting the enthusiasm of non-experts eager for science. performs. (The death toll in the quake was about 2,200, much lower than in 2010, mainly because the epicenter was in a more rural part of the country.)

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

In an article published Thursday in the journal Science, Dr. Kallis and his colleagues describe what citizen science seismometers uncovered about the August earthquake. About 40 miles through the same fault that caused the devastating 2010 earthquake, but further west. The data also revealed some surprises, Dr. Kallis said: At the eastern end of this section, the fault was not vertical, where two tectonic plates are sliding past each other. Instead, the two plates were also being pushed closer together, with the northern one sliding over the southern.

“If we didn’t have an aftershock distribution, we wouldn’t be able to put proper perfect geometry into our models,” said Dr. Calais. “Our assessment of what happened then would have been wrong.”

The Caribbean is sometimes a region of unseen seismic hazards with active volcanoes and earthquake faults. “The Caribbean is its own small-scale Ring of Fire,” said United States Geological Survey seismologist Susan E. Huff. “It’s like the Pacific Rim on a smaller scale.”

But tectonic plates are crashing together at a slower rate, and larger earthquakes are less frequent. The latter half of the 20th century was quite quiet in the region. “People got kind of complacent about it,” Dr. Huff said. “The 2010 earthquake did not surprise any earthquake professional in the world, but it did surprise many people who were not aware of the scientific results.”

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Dr. Huff and Dr. Kallis were two seismologists who traveled to Haiti in 2010. After that year’s earthquake, international organizations provided funding to install conventional seismometers in Haiti, which cost tens of thousands of dollars. , When the 7.2 magnitude earthquake struck on 14 August, none of Haiti’s conventional seismometers were working, although a seismometer at the United States embassy was collecting data.

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

Haiti is politically unstable, plagued by widespread poverty and vulnerable to natural disasters. President Jovenel Mosse was assassinated a 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. Kallis met with Brandon Christensen, chief executive of Raspberry Shake, a Panama-based company that combines a small, inexpensive computer with the Raspberry Pi, which is widely used. The oil and natural gas industries manufacture a seismometer, which costs a few hundred dollars instead of tens of thousands of dollars, to measure small ground motions.

The Raspberry Shake device, smaller than a breadbox, can measure the subtle motion of the ground, though over a smaller range of frequencies than modern traditional seismometers. But they don’t need to be grounded and require only 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 survival in Haiti over a long period of time, meaning no maintenance,” recalled Dr. Calais. He used some leftover grant money to buy five of them, and with colleagues in Haiti, he began looking for volunteers who would be willing to keep one in his home or office. Since then the network has expanded to around 15 devices.

Dr. Calais said the data in Haiti showed that the raspberry shakes were not as capable as traditional seismometers, yet they made scientifically valuable measurements. “When it comes to recording small shakes they are capable of getting the job done,” he said.

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

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The device closest to the epicenter was offline, as the host had allowed its Internet service to die. But he fixed it after feeling the aftershocks. “We have to acknowledge this kind of issue,” Dr Kallis said. “Internet and electricity are never provided in Haiti.”

The researchers were also able to add three raspberry shakes to the area, and all six measured more than a thousand aftershocks, which occurred in the weeks following.

The seismic data, published online, is only part of Dr. Kallis’s motivation to establish the Raspberry Shake network. It aims to spread knowledge about earthquake hazards among volunteers hosting Raspberry Shake in Haiti and a host of others.

“We want to inspire some people in the community to act differently,” said Steve J., a geophysicist at the State University of Haiti and author of the Science paper. Simethe said.

Dr. Simethe, who was born in Haiti, was studying to become a civil engineer, but switched fields after the 2010 earthquake, completing his doctorate at Purdue University with Dr. Kallis, who was then there. was a professor.

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

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

Some research doesn’t even include earthquakes. In a paper published in July 2020 in Science, scientists used data from 300 seismic stations, including 65 raspberry shakes, to observe the global calmness of noise from trains, planes, factories, and a reduction in other human-caused vibrations. covid 19 pandemic.

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

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