Recently, geologists claim that they have identified the main mechanism behind some of the largest earthquakes on the planet.
Large earthquakes occur in subduction zones , where one tectonic plate is being pushed under another. They are especially common around the Pacific and Indian Ocean regions, and can also lead to giant tsunamis.
New research shows that a slow, gradual sliding motion deep below the subduction zone could be the key to understanding how large earthquakes trigger and potentially improving forecasting models to predict them. better in the future.
Large earthquakes often occur in subduction zones.
These slow-slip events don’t happen in every subduction zone, the researchers say, but they could influence how pressure builds underground. Importantly, they move energy in different directions to create super-repulsive earthquakes, and not necessarily follow the motion of the plates themselves.
“Usually when an earthquake occurs, we find that the motion is in the opposite direction of the way the plates move. For these slow-slip earthquakes, the direction of motion is directly down in the direction of gravity instead of the direction of gravity. because of the direction of the plate’s motion,” said geologist Kevin Furlong from Pennsylvania State University.
Using data from high-resolution GPS stations, Furlong and his colleagues analyzed movements along the Cascadia subduction zone (which stretches from Vancouver Island in Canada to northern California) over several years.
A magnitude 9 earthquake struck Cascadia in 1700, and since then slow-slip events (SSEs) have occurred below the subduction zone, traveling short distances at slow speeds. The researchers say they resemble a series of events, and the pattern matches similar data logging from New Zealand.
“There are subduction zones that don’t have these slow-slip events, so we don’t have direct measurements of how the deeper part of the subduction plate moves,” Furlong said.
SSE was first discovered by geologists about 20 years ago and more recently with GPS tools have been developed sensitive enough to capture details 35km underground.
The new study’s findings, which the researchers describe as “quite unexpected” , should help inform future earthquake patterns.
Knowing the direction of the forces that future earthquakes will release is important in planning for them. These natural disasters can be very unpredictable, so any information that can be gathered ahead of time is invaluable.