Thursday, July 25, 2019

Dramatic Before And After Pictures Show Ground Movement In California From Quakes

Dramatic before-and-after pictures show how Ridgecrest earthquakes caused the ground to break in California

But it’s only watching those new satellite images that you will understand how California’s biggest earthquake in nearly two decades caused the ground to break.

Some of the clearest images show long scars on the surface of the Mojave Desert, indicating precisely the 30 miles of earthquake fault — oriented in a northwest-southeast direction — that moved within moments on July 5.
I’ve never seen this before,” said Brian Olson, engineering geologist with the California Geological Survey. “It’s really dramatic and a super-good illustrator, even for the advanced scientists, all the way down to the grade-school kids.
The images show “the scale of movement and the permanency of movement — this ground moved in places up to 13 feet, permanently. It’s not going back,” Olson said.
Some of the most widely circulated before-and-after GIFs that have been receiving attention by California earthquake scientists were created using imagery from Google Earth and DigitalGlobe by an earthquake geologist based in Greece, Sotiris Valkaniotis, who collaborates with the National Observatory of Athens.
In a large section of the fault, images show how land on one side of the fault moved between 3 and 13 feet from the other side, Valkaniotis said.
The animations are an impressive example of what California has undergone for millennia. California sits on the edge of two gigantic tectonic plates, the Pacific and North American. A huge swath of California, from Santa Cruz to Santa Barbara, L.A. and San Diego, is moving northwest toward Alaska relative to the other plate, which is moving southeast toward Mexico.

No comments: