Installed in people’s living rooms, gardens, and businesses across Haiti, a network of low-cost seismometers is assisting scientists in deciphering the inner workings of the magnitude-7.2 earthquake that struck the country’s southern region earlier this month.
After the country’s most recent significant earthquake, a magnitude-7 tremor that killed more than 100,000 people in 2010, the community-science project began, and it has since helped to reveal insights about Haiti’s seismic activity.
The community-seismology project delivers much-needed data in a country where official seismic-monitoring stations are occasionally offline due to a lack of funding.
At this time, the network is identifying aftershocks that are still shaking the region. Seismometer data is sent into a system that shows the locations and magnitudes of Haitian earthquakes in real time on a web-based portal.
Dominique Boisson, a geologist at the State University of Haiti in Port-au-Prince who helps to administer the network, says, “It’s not professional equipment, and there are a lot of limits.” However, “some of the effects are quite nice.”
EXTREMELY DIFFICULT WORK
The network exemplifies how far seismology has progressed in Haiti during the last 11 years.
According to Boisson, when the 2010 earthquake in Port-au-Prince happened, the government had no seismologists and just one official seismic monitoring station.
There are now numerous professional seismologists, as well as 7 official national network stations run by Haiti’s Bureau of Mines and Energy, and 15 community-science stations.
Teams of scientists and technicians were traveling towards the site of the great quake on August 14th, carrying seismometers and other gear to assess how the ground was moving, just days after it struck.
Researchers can better understand why an earthquake happened and the future seismic danger by monitoring the Earth using scientific devices shortly after a quake.
Foreign researchers flew to Haiti and deployed instruments weeks after the earthquake in 2010.
Many of those foreign teams are unable to visit Haiti this year due to COVID-19 restrictions and political unrest following the killing of Haiti’s president, Jovenel Mose, in July.
Instead, Haitian seismologists are leading the charge, such as Steeve Smith, also of the State University, who was delivering Facebook Live seminars about the science of the quake to the Haitian public before going into the field.
The Enriquillo–Plantain Garden fault zone, a tangle of cracks in Earth’s crust where the North American and Caribbean tectonic plates slip past one another, was the epicenter of both the 2010 and 2021 quakes.
It runs the length of Haiti’s southern peninsula, from west to east. In that zone, the 2010 quake occurred on a previously unknown fault. The epicenter of the quake in 2021 is around 100 kilometers to the west, in the Nippes province.
The 14 August earthquake killed at least 2,100 people, while the total death toll has yet to be determined.
According to the US Geological Survey, more than 10,000 people may have died.
As they attempted to seek cover outside, many survivors were buffeted by strong winds and rain from a tropical storm.
According to Boisson of Nature, scientists en way to the area spent the night in their automobiles as rain pelted down, softening the ground and causing landslides as tremors rattled the ground.
He admits that it was “pretty difficult” for them.
SEISMOLOGY ON YOUR OWN
The difficulty of doing research in Haiti inspired the establishment of the community-seismology project in 2019.
That’s when Eric Calais, a seismologist at Paris’ École Normale Supérieure who has spent years studying Haiti’s earthquakes, came across a company that sells seismic sensors to amateurs.
He bought some stations using spare money from a grant to get around the national Haitian network’s inconsistent data.
They’re called Raspberry Shakes because they have small accelerometers that detect when the earth trembles and send the data to be processed and mixed with data from other stations.
These $500 monitoring stations aren’t as advanced as Haiti’s official $50,000 monitoring stations.
“However, they are incredibly good at locating quakes, determining magnitude, and doing basic seismology,” Calais explains.
They also have a consistent source of power and reliable Internet connection because they are in people’s homes and workplaces.
Calais, Boisson, Symithe, and other members of the team solicited people to host the stations.
Boisson had one in his yard until last week, when he disassembled it in order to relocate it closer to the epicenter of the 14 August earthquake.
According to Calais, the host who had the Raspberry Shake closest to the epicenter was disappointed that his station was knocked offline during the quake; he immediately went out and topped up his Internet plan, and the station was back up and operating in no time.
Calais and his colleagues have kept the network of 15 stations running for two years1 thanks to foreign sponsorship, and they plan to expand to 50 or more locations soon.
Other community-seismology networks have sprung up around the world, but the Haiti network is unusual in that it provides data in an area where seismic data is scarce, according to Calais.
The data from Haitian community seismology is fed into Ayiti-Séismes, a statewide experimental system hosted by the Côte d’Azur University in Nice, France.
Ayiti-Séismes also collects data from official seismic stations in Haiti and neighboring countries such as the Dominican Republic and Cuba.
The result is a real-time map of aftershocks in colors of red and orange covering southwestern Haiti.
Susan Hough, a seismologist with the US Geological Survey in Pasadena, California, who has worked in Haiti for many years, including after the 2010 earthquake, says, “The network remains alive and well.”
RISK IN THE FUTURE
According to Calais, the epicenter of the quake is quite close to quakes that happened in 1952 and 1953, which were probably between magnitude 5 and 6. The Enriquillo–Plantain Garden fault zone could yet produce another significant quake in the future.
“We can’t claim it’s over in this area,” Boisson says. Some suspect that the 2010 quake aided the recent one by shifting stress to the region that recently ruptured — and that seismic risk in Port-au-Prince and much of the Enriquillo–Plantain Garden fault zone remains high.
Many experts have been concerned about a distinct important geological region in Haiti’s north, known as the Septentrional fault zone, which caused a huge earthquake in 1842, according to Boisson.
“After 2010, we anticipated this fault would be the source of future quakes,” he explains. “And then it was back to the south.”
According to Calais, almost 600 aftershocks have been registered since the 14 August quake, compared to about 10 in the same period following the 2010 quake.
However, there were certainly more that were not caught. He continues, “We now have extremely strong knowledge on not only where the [14 August] quake happened, but also how large the rupture was and in which direction the fault was descending.”
Understanding why the quake happened and what to expect in the future is “essential.”
The author is: Alexandra Witze works for Nature magazine.