NASA / JPL-Caltech
Curious how much land was shifted after the two major earthquakes last week in Southern California? NASA has just the map for that matter – and it happens to be beautiful, psychedelic art.
On July 4, a 6.4 large scale hit the town of Ridgecrest, north of Los Angeles. The following evening, the area was restored with an earthquake of 7.1. Fortunately, there were no serious injuries or major infrastructure damage.
The map was created by the Advanced Rapid Imaging and Analysis team at NASA's Jet Propulsion Laboratory. It shows rippling rainbows that form a circular pattern around the two shakers' faults.
Every rainbow stripe means that the ground has shifted there by about 4.8 inches. It is the same logic as a topographic map, where lines that are closer together indicate steeper slopes. In this case, the closer the rainbow stripes are, the more the ground is displaced by the temblor.
Eric Fielding, a geophysicist at JPL, says that the parts of the map along the fault where the colors appear jumbled suggest even more dramatic ground motion.
He explains how they mapped the changes.
"We have taken a radar image before the earthquake and another picture after the earthquake" Fielding tells the NPR. They then compared each point's change between the two images. "It allows us to measure the amounts that the Earth has moved either towards or away from the satellite."
The researchers used data collected by radar from the Japanese satellite ALOS-2. Fielding says the radar can detect the movement as small as half an inch.
Here is another map produced by NASA showing the same information in a different way:
In this, the difference in color makes it easier to see that the earth's surface moves in different directions along the fault. "We can clearly see the two sides of the error moving in opposite directions," he said.
The long line of green circles on the map that extends from northwest to southeast is the fault that broke during the major earthquake on July 5. Fields says the fault is about 30 miles long. The green circuit line that intersects with that error almost at the right angle is the crime from the minor earthquake on July 4th.
"6.4 made an error that goes almost exactly perpendicular to 7.1," he said.
The blue area west of the largest fault was moved as much as 2.7 feet northwest during the largest earthquake, while the red surface moved as much as 2 meters southeast, according to NASA.