Earthquake Swarm Continues In German-Czech Border Region
...In recent years, scientists have noted an increase in the movement of magma towards the earth’s surface in the Cheb Basin, western Czech Republic. They say rising magma could be one of the causes of the earthquake swarms, which regularly occur in the Vogtland, North-West Bohemia, the Fichtelgebirge and the Upper Palatinate. The last earthquake swarm to occur before this week’s activity was in 2008.
Laser flashes expose Oregon earthquake faults
Scientists using lidar, a system that bounces laser flashes off the ground, have found hidden seismic faults in Oregon, including one on the northern flank of Mount Hood that appears to be active — and dangerous.
PORTLAND — On the northern flank of Mount Hood, a scar in the earth's crust stretches for several miles beneath the fir trees that hide it from airborne observers.
It is the mark of a previously undetected seismic fault that appears to be active — and dangerous. The last time the fault ruptured, opposing sections of the earth's crust jolted 6 feet apart horizontally, leaving a miles-long raised edge, or scarp.
At shallow crustal faults, earthquakes last for seconds rather than minutes and the ground-shaking is more limited in reach than from a subduction quake. But shallow faults can be deadly and massively destructive to nearby cities. The magnitude 6.3 earthquake in February on a shallow fault beneath Christchurch, New Zealand, killed more than 180 people and collapsed modern, seismically reinforced buildings.
Connections between the faults and volcanic activity at Mount Hood are uncertain. At Mount St. Helens, a shallow crustal fault played a major role in the 1980 eruption. A magnitude 5.1 earthquake on the fault triggered a landslide that collapsed the north side of the mountain.
Nearly all of the recently disclosed faults in Oregon remain a complete mystery. Progress on defining the risks has been slow because the state has invested little in the field work required."It was probably a magnitude 6 or 7 earthquake," says Ian Madin, chief scientist with the Oregon Department of Geology and Mineral Industries. "That would be felt in Hood River. It might be damaging in Hood River valley communities."