OLYMPIA — Washington voters Tuesday were easily passing a proposed amendment to the state constitution intended to help keep the government running during a large-scale disaster, such as a catastrophic earthquake.

In Tuesday’s results, Senate Joint Resolution 8200 had nearly 66% of the vote.

The Legislature this year passed the resolution, but as a proposed constitutional amendment, voters make the final decision.

Currently, the Washington constitution allows for contingency planning in the event of an enemy attack on the United States — but not for natural or other human-caused disasters. The amendment would allow such planning to include those events.

In the event of a disaster, continuity-of-government laws outline temporary succession plans for the duties and powers of state and local elected officials. The laws also set guidelines for emergency sessions of local governments or the Legislature, eliminating, for example, the number of surviving legislators needed to approve measures. The plans could also give state legislators permission to convene somewhere other than the Capitol in Olympia, if needed.

The odds of a shallow fault rupturing somewhere in the Puget Sound region, potentially triggering a mega-earthquake of magnitude 9.0 or more over the next 50 years are greater than 1 in 7, according to the U.S. Geological Survey. That’s three times more likely than picking a winning Powerball number.

If approved in final vote tallies, Senate Joint Resolution 8200 would allow legislation passed this year — which gets that planning started — to take effect.

The proposed amendment passed with wide majorities in the Legislature. But a handful of opponents have said they’re concerned it was too vaguely worded for such a strong expansion of legislative authority.