In August 2021, a devastating disaster earthquake of magnitude 7.2 tore up the Tiburon peninsula in Haiti. The nearest conventional seismic stations were 120 kilometers from the earthquake’s epicenter, too far to capture near-field seismic information, which is important for fully understanding the main shock and its aftershock sequence. Fortunately, these stations were supplemented by a network of small devices called Raspberry Shake (RS) seismometers, discreetly hidden inside houses.
Raspberry Shakes cost a fraction of the price of conventional seismometers. They easily connect to the internet (unlike conventional seismometers, which may require manual data uploads), making them perfect for a community-run seismic network, said Eric Calais, geophysicist at the École Normale Supérieure in Paris. He helped initiate this project in 2019 in collaboration with researchers from the State University of Haiti. The team demonstrated the usefulness of the devices in a paper recently published in Science.
Steve Symith, lecturer at the State University of Haiti and researcher at the URGéo Research Laboratory, was responsible for the installation of 13 of the 15 operational RS devices. “When I realized that every piece of equipment I had installed worked perfectly,” he said, “I was very excited.”
The network captured the initial shock and uploaded the data to an online database in real time. In the days immediately following the earthquake, Symithe braved the aftershocks, gang insecurityand a tropical storm to install three more Raspberry Shakes and 12 conventional seismic sensors near the epicenter of the earthquake. The additional devices provided the network with data to better predict the impact of the earthquake continuous aftershocks.
Community is key
A reliable community-run seismic network is an attractive alternative in seismically active locations that lack the government resources needed to maintain conventional seismic stations, said Emilie Wolin, seismic network manager at the Albuquerque Seismological Laboratory of the US Geological Survey, who was not involved in this work in Haiti. Wolin mentioned a similar project in Nepal. “I think these kinds of projects are a really good way to do real-world seismology under all the constraints that exist in the real world,” she said, “and I think that’s great to get this kind of data.”
Wolin has seen problems in international development projects following earthquakes in which outside agencies contribute new instrumentation and monitoring systems. “Everyone likes to come in and build new things,” she said, but “it’s a lot harder to convince funding agencies to keep paying for telemetry and maintenance.” The network in Haiti, on the other hand, was developed and is maintained locally and relies on teamwork between the public and scientists – a collaboration that Symithe and Calais hope to see grow.
A seismic network more than its instruments
Now that the researchers have demonstrated that RS devices can create a reliable seismic network, their next ongoing goal is to help community members become seismic risk ambassadors in Haiti, Calais said. The participation of sociologists helped the team of seismologists provide useful information to people hosting a Raspberry Shake, and these experts will continue to help participants move forward.
Understanding the people involved in your project is key, said Laure Fallou, a sociologist at the Euro-Mediterranean Seismological Center who is helping to extend the project beyond seismology. She and other sociologists on the team interviewed hosts to gauge their expectations of the researchers as well as the project, which helps to ensure that the cultural context of the work is not obscured by the data. seismic.
“A seismic network is [composed not only] sensors but also people,” Fallou said. “We’ve really created a network of people and sensors working together to reduce the earthquake risk a bit.”
This data has also been used to inform future policies. Data collected during the August earthquake showed local ground motion was greater than current building codes could handle. Existing codes were quickly written after the devastating havoc 2010 earthquake and were based on data from regional seismic stations available at that time. Twelve years later, the community network will provide more precise data to improve these codes.
“After the 2010 earthquakes, we had to rely on international scientists to come and tell us what happened,” Symithe said. “But this time, 2 days after the main event, it was local scientists on the ground doing the same work. It’s a big improvement.
—Fionna MD Samuels (@Fairy_Hedgehog), science writer