The U.S. Geological Survey confirmed this morning that a tiny quake 12 days before Saturday’s Oso mudslide could not have triggered the disaster.
“Seismograph readings show no indication of an earthquake in association with the landslide,” said a statement from the agency.
However, recordings from the Pacific Northwest Seismic Network based at the University of Washington show that the slide caused local ground shaking for over an hour.
John Pennington, director of Snohomish County Emergency Management, had raised the possibility that the mudslide may have been triggered by the quake at a news conference Tuesday morning.
The quake measured 1.1 on the magnitude scale.