According to scientist Won-Young Kim of the Lamont-Doherty Earth Observatory of Columbia University, the whole rockslide motion at State Line Lookout a few days ago took about 35 seconds.
The seismic signals were strong at all three stations in Palisades, NY starting at 7:28 p.m. May 12.
"The duration of the strong signal is about 21 seconds, followed by weaker ground motion for additional 15 seconds, so the whole rockslide motion took about 35 seconds. Is this what people experienced?" Dr. Kim said in an email to an official at the Palisades Interstate Park in Alpine, NJ.
A screenshot of Lamont's seismographic data is attached to this report.
A Hastings resident sent us this report:
Saturday night a large portion of the Rock Face from the Palisades Park let loose, it took out all the trees that were previously in that area. Leaving a large cloud of smoke from the debris hovering over the water. I live in Hastings and this is directly across the river, on the NJ side.
Anyone see this? Please give us details—and add your photos.