In short, yes. Here's the kicker - some of the sinking is man made. Parts of California suffer from what geologists call subsidence caused by groundwater pumping. The Santa Ana basin is currently sinking about a 1/2 inch per year. This is caused by a seasonal filling and draining of natural underground aquafers. The problem is that each year these aquafers are drained to lower levels, causing compaction of the surrounding rock and soil which prevents the aquifer from ever filling to its previous capacity (demand rises as the capacity lessens, water must be drained to lower and lower levels, which causes more compaction, which lessens the capacity, which...you get the idea). This results in the gradual lowering of elevation in parts of the state. Below is an excerpt from http://www.space.com/scienceastronomy/gps_fooled_010822-1.html "A new satellite-based study shows parts of the Santa Ana basin, near Los Angeles, rise and fall more than 4 inches (11 centimeters) every year. That would be fine if the land masses returned to some equilibrium. Instead, over time, the elevation of much of the land in the greater Los Angeles area and beyond is gradually dropping as a result of the land's seasonal movements. Vast areas of the Golden State are sinking, threatening to disrupt the flow of water and sewage. It's a growing problem not confined to California, and difficult to spot in other parts of the country. Nature has little to do with it. For Los Angeles, as ever, it's about water. Local water districts that purchase water from outside the area pump it into huge, natural underground reservoirs to store it in winter months. These aquifers, as they are called, are regions of rock, sand and soil that can extend for many square miles and through which water flows freely. Every summer, the water is withdrawn from these subterranean banks. But each year, the withdrawals exceed the deposits. "Every year when they pump water out, they're pumping it to a new, lower level," said Gerald Bawden, a U.S. Geological Survey scientist who led the new study, which appears in the Aug. 23 issue of the journal Nature. The seasonal draining causes rock and soil to compact to an extent that prevents an aquifer from ever filling to its previous capacity -- something scientists have understood since the late 1920s. Like a hardened sponge, the compacted material simply can't hold water as well as before. The result is that in addition to the seasonal fluctuation, the ground in some places also sinks steadily over time. It's a process geologists call subsidence." "...Subsidence caused by groundwater pumping is nothing new. One region of California's Central Valley, well north of the Los Angles area, is known to have subsided roughly 30 feet (9 meters) since the late 1940s. Other parts of the country are also affected. In 1997, the USGS measured long-term sinking in select locations in or near these cities: West of Phoenix, Arizona: 18 feet (5.5 meters) Houston, Texas: 9 feet (2.7 meters) Las Vegas, Nevada: 6 feet (1.8 meters) Measurable side effects have already occurred. At Edwards Air Force Base in California, a giant crack in the ground caused by groundwater siphoning once rendered a backup runway designed for the space shuttle unusable. Bob Pierotti saw that huge fissure back in the early 1990s. He called it "the mother of all fissures, a big gaping crack" that was some 20 feet wide and hundreds of yards long. Pierotti is a geologist with the southern division of the California Department of Water Resources. He says that in general, subsidence is viewed seriously by those who manage water districts." This is a really interesting article, well worth the read!

scymitar72's answer tells one reason why some parts of California are sinking. There is another part of the state that is sinking for a completely different reason. The floor of Death Valley is also sinking because of the tectonic stresses in the area.

This often comes up when when people talk about earthquake activity along the Pacific coast of the United States. Seismologists have predicted that a massive scale (8.0 or higher on the Richter Scale) earthquake will shake the region sometime within the next 30 years or so. This is the so-called "Big One" that makes many Californians understandably nervous and inspires a variety of apocalyptic disaster speculations. But while the Big One would definitely wreak mass destruction, it would not sink part of California into the ocean, nor would it break the state off from the rest of the country. The idea comes from a misunderstanding of the seismic forces that cause earthquakes in the region. Powerful earthquakes occur frequently along the west coast of the United States because the region is near a boundary between two tectonic plates. If you've read How Earthquakes Work, then you know that the earth's surface is made up of large, rigid plates that slowly drift over the mantle layer below. At the boundaries between plates, a number of things can happen. The Pacific plate and the North American plate simply grind against each other -- one creeps slowly northwest and one creeps southeast. This boundary forms a fault line that extends under the ocean and on land along the west coast of the United States. The San Andreas fault in California is the piece that's on land. Smaller faults form in the crust material near the boundary line due to the forces of the plates pushing on each other. Friction builds up along faults because the two sides are pushed very tightly together. If the force of friction exceeds the forces moving the earth, the two sides will become "locked," so they stop creeping. When this happens, tension builds up along the fault line until the force of movement is great enough to overcome the force of friction. Then the pieces of earth suddenly "snap" into place, releasing a large amount of energy that causes earthquakes in the earth's crust. Many scientists estimate that there is enough tension built up along some locked California faults, that when they do finally slip, the earthquake will be extremely powerful. The Hayward Fault particularly concerns these scientists because it runs under heavily populated areas in and around Los Angeles. The notion that part of California will break off was likely inspired by the San Andreas fault. After all, since the fault goes right through California, one part of the state is on the Pacific plate and one is on the North American plate. If those plates are moving in different directions, it make sense that the two pieces of California will move in different directions too. And this is indeed the case. But, even in a massive shift along the fault, the plates travel an incredibly short distance -- a matter of feet in the most extreme shifts. The tension cannot build up to the point that one entire mass of land will shift many miles in relation to another one, so you will not see any sizable piece of land breaking away from another. Instead, the pieces of land will move away from each other very slowly, taking millions of years to make large scale changes. One end of California may slowly drift so that it is eventually under water, but this can hardly be construed as "sinking into the ocean."

HAVE YOU EVER HEARD OF BROTHER WILLIAM BRANHAM ? WELL , HE WAS OUR LAST KNOWN PROFIT-- HE PREDICTED THAT CALIFORNIA WOULD SINK AND THAT THE WAVES WILL REACH KENTUKY ! IT WILL HAPPEN ! IT WILL HAPPEN VERY SOON ! WHEN HE FIRST MADE THIS PREDICTION -- EVERYONE SAID " THERES NO WAY " BUT , NOW MANY , MANY YEARS LATER SCIENTEST NOW AGREE !