Shifting planet: Indonesia’s 8.6 left scientists scratching their heads, now Italy’s 6.0 quake does the same

May 24, 2012 – ITALY – A strong and unusually shallow earthquake struck northern Italy over the weekend, fracturing pavement, sending torrents of brick and rubble raining down from buildings, and killing seven people. The powerful shaking was a first for the region in centuries — and fairly surprising to seismologists. Data indicate the magnitude 6.0 quake, which struck just after 4 a.m. local time on Sunday (May 20), just north of Bologna, was a thrust quake — the type of earthquake caused when two tectonic plates smash together — yet it occurred at a depth of just 3 miles (5 kilometers). “It is kind of surprising that it’s that shallow, because it’s pretty far from the plate boundary,” said Paul Caruso, a geophysicist with the U.S. Geological Survey. “Normally we expect things to get deeper as they move northward,” he told OurAmazingPlanet. The quake hit about 470 miles (750 km) north of the plate boundary — the place where the two colliding plates meet — which runs along the sole of Italy’s “boot.” It is here that the African plate is plowing slowly northward, crashing into the Eurasian plate. Caruso explained that the shallower a quake, the more damage it can cause. “If a quake is 500 kilometers deep, and you’re right on top of it, you’re going to feel it a lot less strongly than if it’s 5 kilometers deep,” he said. “As the seismic energy moves through the ground some of it is dissipated.” Several aftershocks have rocked the affected region, and it’s not clear if this recent earthquake is a harbinger of things to come. “We don’t know if this is going to trigger more activity in this area or not,” Caruso said. “We would expect to see aftershocks in the area for a while.” There have already been at least 100 aftershocks. The shaking could continue for weeks or months, he said. –Discovery News

Physics.org said: “The Sumatra earthquake’s magnitude surprised scientists because it was the most powerful strike-slip earthquake ever recorded. The quake was also unusual in that the rupture was in the middle of an oceanic plate rather than at the boundary between two plates.” Now, we’re seeing these uncharacteristic large magnitude earthquakes erupt far from tectonic plate boundaries like Sumatra and Italy with rather shallow signatures- this is generally not supposed to happen. Earthquakes are doing things which haven’t been generally characteristic of earthquakes in  the past. This is further indication that the planet’s seismic dynamism is shifting and change is accelerating.  –The Extinction Protocol

contribution by Shaun G.