A network of cheap seismographs installed in the living rooms, gardens and workplaces of Haitian people is helping scientists unravel the inner workings of the magnitude 7.2 earthquake that destroyed the southwestern Caribbean this month. Community science work started after the country’s last major earthquake (a magnitude 7 earthquake in 2010 that killed more than 100,000 people) and has since helped reveal detailed information about seismic activity in Haiti.
In a country where official seismic monitoring stations are sometimes offline due to limited resources, the community seismology project provided much-needed data. Currently, the network is detecting aftershocks that continue to disrupt the area. Its seismometer inputs data into a system that shows the location and magnitude of the earthquake in Haiti. Web-based portal real time.
“This is not a professional equipment, and it has a lot of restrictions,” said Dominique Boisson, a geologist at the Haitian State University in Port-au-Prince, who helped run the network. But “some results are very good.”
The network highlights the progress made in Haitian seismology in 11 years. Boisson said that when there was an earthquake near Port-au-Prince in 2010, there were no seismologists in the country and there was only an official earthquake monitoring station. now, There are several professional seismologists, And 7 sites in the official national network operated by the Haitian Bureau of Minerals and Energy, and 15 sites in the Community Science Network.
In the days following the massive earthquake on August 14, a team of scientists and technicians brought seismographs and other instruments to the epicenter to measure the movement of the ground. Monitoring the earth with scientific instruments immediately after an earthquake can allow researchers to better understand the cause of the earthquake and the risk of future earthquakes. After the earthquake in 2010, it took several weeks for foreign researchers to fly to Haiti and deploy instruments.
This year, due to COVID-19 restrictions and political instability following the assassination of Haitian President Jovenel Moïse in July, many foreign teams have been banned from traveling to Haiti. Instead, this work was led by Haitian seismologists, such as Steeve Symithe, who also worked at a state university. Before he entered the field, Streaming Facebook Live presentation Introduce the science of earthquakes to the Haitian public.
Both the 2010 and 2021 earthquakes occurred on the Enriquiyo-Plantago Garden fault zone, a crack in the crust where the North American and Caribbean tectonic plates slide across each other. It stretches from west to east on the southern peninsula along the coast. The 2010 earthquake occurred on Previously unknown faults in the areaThe epicenter of the 2021 earthquake is about 100 kilometers west of Nipez Province.
At least 2,100 people died in the August 14 earthquake, but the total is not yet counted. The U.S. Geological Survey estimates that there may be more than 10,000 deaths. Many survivors endured the torrential rain brought by tropical storms while trying to hide outside. Boisson said that the scientists who went to the area spent the night in their cars because the rain poured down, softening the ground and causing landslides as the aftershocks shook the ground. natureHe said that for them “it was very difficult.”
The challenge of fieldwork in Haiti inspired the creation of the community seismology project in 2019. At that time, Eric Calais, a seismologist at the Ecole Normale Supérieure de Paris, happened to work for a company that sold earthquakes in Haiti. Seismic station for amateurs. Trying to circumvent the intermittent data on Haitian.com across the country, he bought some radio stations with the remaining money from a grant. Called Raspberry Shakes, they contain tiny accelerometers that can detect when the ground is shaking, and send that information for processing and mixing with information from other sites.
These US$500 monitoring stations are not as complicated as the official Haitian monitoring station valued at US$50,000. “But in terms of locating earthquakes, determining their magnitude, doing basic seismology – they are really excellent,” Calais said. And because they are in people’s homes and workplaces, they usually have a stable power supply and reliable Internet access. The team includes Calais, Boisson, Symithe, and many others, recruiting people to host these stations. Until last week, Boisson had one in his garden when he demolished it and moved it closer to the epicenter of the August 14 earthquake. The host of the Raspberry Shake closest to the epicenter was annoyed that his station was offline during the earthquake; Calais said that he immediately ran out and recharged his Internet plan, and the station quickly resumed operations.
With funding from international supporters, Calais and his colleagues ran a network of 15 sites for two years1; Their goal is to increase to 50 or more sites as quickly as possible. Calais said that community seismology networks have sprung up in other parts of the world, but the Haitian network is unique in providing data, otherwise the region rarely collects seismic data.
Seismological data from the Haitian community is input into a national experimental system called Ayiti-Séismes, which is hosted by a website operated by the University of Nice-Côte d’Azur, France. Ayiti-Séismes also extracts data from official seismic stations in Haiti and nearby countries, including the Dominican Republic and Cuba. The result is a real-time map of aftershocks covering southwestern Haiti, showing shades of red and orange. Susan Hough, a seismologist at the U.S. Geological Survey in Pasadena, California, has worked in Haiti for many years, including after the 2010 earthquake. She said: “The network is still alive and working well. “
Calais said that the epicenter of the earthquake was quite close to the earthquakes that occurred in 1952 and 1953, and the magnitude may be between 5 and 6. In terms of future risks, the Enriquillo-Plantain Garden fault zone may still trigger another major earthquake. “In this field, we cannot say that it is over,” Boisson said. Some speculate that the 2010 earthquake contributed to the recent earthquake by shifting pressure to the area that had just ruptured — and that most areas of the Port-au-Prince and Enriquiyo-Plantaria fault zone are still at high seismic risk.
Boisson pointed out that many scientists have been worried that there is a different main geological area in northern Haiti, called the middle fault zone. It caused a major earthquake in 1842. “After 2010, we think this will be the fault” that will cause future earthquakes, he said. “Then it’s in the south again.”
Calais said that so far, about 600 aftershocks have been detected in the August 14 earthquake—and there were about 10 aftershocks in the same period after the 2010 earthquake, although there are undoubtedly more aftershocks that have not been detected. arrive. “We are now not only about [14 August] The earthquake occurred, the width of the rupture, and the direction in which the fault was inclined,” he added. “This is essential for understanding the cause of the earthquake and the expectations for the future.”
This article is reproduced with authorization and has been First published August 20, 2021.