If I had my choice, I would rather live out the aftermath of an earthquake. Which although has the potential to destroy a lot of property and infrastructure in the actual earthquake and the immediate in terms of fire etc, it sure beats living in the aftermath of a flood where water can damage everything beyond any semblance of repair.

As for the question of water. Yes it may be hard to come by in the immediate quake center but there is enough US logistical support such as the military that has the ability to not only clean and sanitize water but also desalinate salt water if required. Also I am sure other countries such as Canada would deploy their DART team which can provide up to 50,000 liters of clean water per day.

Interesting related note to this. My wife who went over with a NGO to the Philippines immediately after Typhoon Haiyan, relayed to me that once aid from countries from around the world ramped up, they were almost overwhelmed in terms of logistics and supplies pouring in, even though that country does not even have close to the same infrastructure as California or any other major US regions.

In the event of a real major earthquake, I would suspect the same logistics and support would flood into the California area and there would be more then a couple of aircraft carriers and other navy ships anchored off the coast along with 1000's of hands of help coming onshore in a very short time. Not to mention the vast US civilian and military air support that would be put to use.