A member shall receive credit under this part for time during which the member is prevented from performing creditable service subject to coverage under the Defined Benefit Program, by act of God, or by reason of the closing of a school by any duly authorized officer or body. If by reason of a member’s Japanese ancestry, the member was required by the Wartime Civil Control Administration to leave his or her teaching position in California and returned prior to July 1, 1972, to service subject to coverage under the Defined Benefit Program, the system shall give the member four years of service credit under this part.