California is one of the United States of America, and is located on west coast of the U.S. along the Pacific Ocean. It is prone to severe earthquakes.
On their return from a trip to Australia, Dorothy Gale and her Uncle Henry landed in San Francisco. Henry traveled on to Hugson's Ranch while Dorothy stayed with friends for a week. On her way to reunite with him, Dorothy and her cousin Zeb Hugson fell down a crack in the earth caused by an earthquake and landed in the Land of the Mangaboos. (Dorothy and the Wizard in Oz)
L. Frank Baum lived most of his life in the Midwest, but as he gained success as an author and began to dabble in film, he moved to California where he spent the last few decades of his life. He was struck by its beauty and even wrote a short story about it called "Nelebel's Fairyland".