Destruction. If any building or structure in which a nonconforming
use is conducted is hereafter removed, or destroyed by fire, wind,
explosion, structural failure or other natural cause, to the extent
of 50% or more of its true market value at the time of such damage,
as adjusted from assessed value based upon State Board of Equalization
rates, it shall not be repaired or rebuilt, unless the appropriate
variance is granted by the Board of Appeals.