An international research team says it may have found a previously-unknown source of fatal earthquakes: a phenomenon called "diking."

Though the term is sure to delight every kid under the age of 16, its effects can be devastating. Diking happens when two tectonic plates move apart, making room for magma to rise up from deep inside the Earth. The magma forms a wedge-like structure called a dike, which starts pushing on the rocks around it and creating growing pressure. You know how a dike is — you give it an inch, and it grows a mile.

Although diking has been known about for a long time, it was previously thought to only have a small effect on civilization, as it seemed to only cause small earthquakes. However, the new research suggests that dikes could also be responsible for some large earthquakes, with magnitudes of six to seven on the Richter Scale.

One earthquake the team investigated was the magnitude 6.2 earthquake in the Democratic Republic of Congo in 2002. The earthquake took place eight months after a volcanic eruption, hinting that diking could be responsible for both. Together, the two devastating events killed more than 100 people.

"The Kalehe earthquake was the largest recorded in the Lake Kivu area, and we wanted to find out whether it was coincidence that, eight months before the earthquake, Nyiragongo erupted," said Christelle Wauthier, assistant professor of geosciences at Penn State, who led the study. Comparing seismic activity with changes in the terrain observed at the time, the researchers concluded that a dike may have been at play in both events.

Knowing that a relatively small dike could have such disastrous events could help seismologists predict future natural disasters before they happen.

The researchers report their findings in the current issue of Geochemistry, Geophysics, Geosystems.

Photo: U.S. Geological Survey | Flickr

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