The geological threat is Rattlesnake Ridge on the Eastern side of Union Gap and like its namesake, it's poised to strike. Unlike the uncoiling and lightning-quick bite of a viper, the ridge is taking its very own unnervingly sweet time, keeping geologists, emergency managers and nearby residents guessing.

Photojournalist Jack Balzer and I took a helicopter ride to the ridge on Thursday (Jan. 4) for an up-close look, and there is no doubt the earth there is on the move. The questions are where, when and how much?

The Yakima Office of Emergency Management's senior planner is Horace Ward, who says, “Geologists believe this (slide) will happen within the next month or so" with the best case scenario having the 8 million tons of earth move south, but stay within the nearby quarry.

The worst-case scenario is the slide material pushes beyond the quarry and onto Interstate 82. A slide to the west threatening the freeway and the Yakima river isn’t considered a serious possibility so far.

Thorp Road is closed between Birchfield and Gangl roads because of  the danger of falling rocks, and the Washington State Department of Transportation says the area of greatest concern along I-82 is between mileposts 37 and 39, south of Union Gap.

The Emergency Management office is advising residents in about 15 homes in the area to leave under a Level 3 evacuation order and arrangements for that are being made.

 The bird's-eye view was spectacular. As floods, slides and Mount St. Helens have all shown us over the years, when Mother Nature wants to move, there is little we can do but hope to get out of her way in time.

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