Actually, it's 10 percent of the replacement cost of the building. If you are insured at $600,000, that's what the insurance company projected as the cost of replacing the house. A ten percent deductible would mean you would have to incur repair costs of more than $60,000 before the insurance kicks in. If you lose your fireplace, have to rebuild or repair some walls that twist out of position, patch or replace sheetrock and stucco, redo some plumbing and repair damage from leaks, replace a furnace that topples over and fix that sort of damage, you might hit $100k.
My father always said if you live in fire and earthquake country, maximize your mortgage. When the SHTF, partner with your "friends" at the bank to get major damage repaired, as their interests are aligned with yours. If there is too much damage and not enough money, let them have the property and minimize your loss.