Central America drives forward earthquake early-warning technology

Public tests of an earthquake early-warning system are currently taking place in Nicaragua. The tests are latest steps in a collaborative initiative to build a warning system for four countries in the region.

The project, known as Alerta Temprana de Terremotos en América Central (ATTAC), was presented at the Seismological Society of America’s Annual Meeting. It is a collaboration between the national seismic networks in Guatemala (INSIVUMEH), El Salvador (MARN), Nicaragua (INETER) and Costa Rica (OVSICORI-UNA) and the Swiss Seismological Service at ETH Zürich, with funding from the Swiss Agency for Development and Cooperation.

Central America is one of the highest-risk areas in the world for earthquakes due to being a large subduction zone.

In the past 24 hours, the area was shaken by five quakes of magnitude 4.0 or above, 26 quakes between 3.0 and 4.0, and 31 quakes between 2.0 and 3.0. One of them, of a magnitude of 6.7, struck off the cost of Nicaragua, and was also felt by neighbouring countries El Salvador and Costa Rica, according to the United States Geological Survey.

“In every one of these countries, in living memory, earthquakes have occurred that have had significant fatalities, often in the capital cities,” said ETH Zürich’s project coordinator John Clinton. “More than twenty thousand people have died in two of the four countries [Nicaragua and Guatemala] in the 1970s, so there is raw feeling and raw emotion. Further, on a regular basis, people are experiencing felt earthquakes.”

Earthquake early-warning algorithms have been installed in all four countries as part of ATTAC, and 71 strong-motion stations have been installed to supplement sometimes patchy coverage, most notably in Guatemala.

The systems do not just comprise stations in the ground, but are also capable of recording strong motion data with low latencies. Recent tests demonstrate that the system can produce warnings seconds before the strong ground-shaking S waves arrive from offshore shallow subduction-zone earthquakes. This usually happens within 10 to 20 seconds of their origin times.

Late last year, the Nicaraguan project partner INETER began sending warnings to test users at about 70 different institutions in Managua, including markets, airports, embassies, and civil and defence ministries. The warnings are sent using a digital TV platform in collaboration with Japanese engineers developing local digital TV services that are already established in the region.

“Even though digital TV is the vanguard of what we’re doing with regards alert delivery, we’re also looking at cellphone alerts as well as sirens, like in Mexico City,” said Frederick Massin, of the Swiss Seismological Service at ETH Zürich

Unlike other countries’ earthquake early-warning systems, such as the US’s ShakeAlert, the alerts are not delivered only to specific areas where ground shaking reaches a certain intensity threshold.

“The expectation in these countries is that any alert is better than no alert,” Clinton added. “This means that we can take a risk and start implementing the system right away.

“Together with each national institution, we have succeeded to build EEW systems that work similarly well in each country despite their manifold differences. We have the potential to provide a ShakeAlert-style system across Central America.”

The project is planned to last two more years, in which the researchers expect to conduct public earthquake early-warning operating in Nicaragua and a get good head start on operations in the other three countries.

“Together with each national institution, we have succeeded to build EEW systems that work similarly well in each country despite their manifold differences,” Clinton said. “We have the potential to provide a ShakeAlert-style system across Central America.”