The area where the landslide took place is not yet stable.

Images taken by NASA's (click here) Operational Land Imager on Landsat 8 reveal the extent of a massive landslide that has blocked off Big Sur's Highway 1. On the left, an image taken prior to the landslide (April 20), in the middle, an image taken after a smaller landslide that preceded the current one (May 17), and on the right, an image of the bigger landslide (taken on May 22)

The top of the hill increased it's instability.

..."This is a large slide preceded by smaller slides, which is not uncommon," Thomas Stanley, a geologist and researcher for NASA, said in a statement. “Much of the California coastline is prone to collapse, so it’s fortunate that this landslide happened in an unpopulated location.”...

It looks to me as the top of the hill became more unstable over that MONTH, the more and more debris carried down to the landslide area. 

There is a reason this area of California is unpopulated for the most part.

DO NOT ENTER THE AREA.

May 27, 2017
By Benjamin Oreskes and Shelby Grad

What a mess: (click here)

The landslide that closed Highway 1 south of Big Sur is shaping up to be a major challenge for engineers. They’re looking at 1.5 million tons of rock and mud over the highway and into the ocean. The landslide was a third of a mile wide and 40 feet at its deepest. What once was a steep drop into the Pacific is now a broad, sloping bench extending almost 250 feet beyond the shoreline. By some estimates, the collapse had added 15 acres to the coast, a little more than 11 football fields including the end zones. And the worst might not be over, said field inspectors who had just returned from the slide. Listen closely, and you’ll hear a sound of water running like rain through the rocks and dirt. The slide at Mud Creek is still moving....

Big Sur 360 degree view (click here)

M 4.1 - 12km W of Isla Vista, California (click here)

2017-05-17 04:42:25 UT1c34.419°N   120.002°W2.3 km depth