>>4706161California is the 11th highest state by average elevation at 2,900 feet (880m). In order to fully submerge the entirety of California, the sea level must rise at least 14,510 feet (4423m). In order to sink California's central valley and all of its major coastal cities, the sea level must rise at least 500 feet (150m), which would also sink all of Florida, Louisiana, Rhode Island, and Delaware.
The 8 "mountain" states along with Oregon and Mauna Kea of Hawaii, all have an average elevation higher than 3,280 feet (1000m) and each of the mountain states has areas of "high plateau" that is at 5,000 feet (1500m) or higher and takes up a very large area the size of some east coast states.
A more likely way to temporarily devastate coastal California is to just wait until another 7.0M or greater earthquake happens again.
