Unfamiliar Earthquake A swarm on the border of Germany and the Czech Republic may indicate that magma is moving deep below the surface.
The quakes occurred in Vogtland, an area known for swarms of regular, low-level earthquakes. These swarms tend to last for several weeks and produce mostly mild shaking. He said the largest known earthquakes from the region had a magnitude of about 4.5 Torsten Dahma geophysicist at the German Research Center for Geosciences GFZ who is leading a project to monitor this area.
Dahm and his colleagues recently completed the deployment of a new network of seismometers installed in wells in the Vogtland region. These seismometers picked up a seismic swarm in late March that, unlike others seen in the area, had the center of the swarm jumped 9 miles (15 kilometers) to the north, compared to previous swarms. Instead of occurring on a vertical underground fault line, it appears to have occurred on a near-horizontal underground structure.
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“For us, this was a bit of a new observation and a bit of a surprise,” Daham told Live Science. This indicates a complex seismic situation beneath this picturesque area of hills and green meadows.
Vogtland is far from the edges Tectonic plates. Dahm said the details of why earthquakes occur in the area are still unclear, but they are most likely the result of carbon dioxide rising from molten fluids at a depth of about 30 miles (50 km). Dahm said there are no active volcanoes in the area, and there is little evidence of ancient volcanic activity.
One of the key questions the research team is asking is whether the melted magma itself is actually emerging from the mantle into the crust beneath this region, or whether the earthquakes are caused by fluids and gases produced by the magma.
Compressive forces in the crust likely prevent this magma from erupting, but it may accumulate in the crust over time, Dahm said. If so, this would have implications for the evolution of new volcanoes over tens of thousands or hundreds of thousands of years. In other words, volcanoes could one day erupt in this currently quiet region if magma accumulates. Or the magma may simply remain below the surface, causing nothing more than small tremors.
The results may also have implications for seismic activity in other areas where volcanic activity is possible.
“There’s a good opportunity now with these very precise observations of earthquakes to better answer the question, what really causes earthquake swarms?” Daham said.