It was one of the most devastating natural disasters in Washington state history: in March 2014, a landslide killed 43 people in Oso near Seattle, the deadliest landslide in U.S. history. And not many people have any idea if they’re at risk.

Research by geologists at the University of Washington examined debris buried by past landslides in the region and found that, surprisingly, landslides happen there a lot more often than thought — a matter of hundreds and not thousands of years, and they’ve been accelerating in the last millenium.

So how do you know if the area where you live is at risk of such a sudden landslide, which can occur without warning and without any time to escape?

Areas with lots of logging appear to be susceptible. While more research needs to be done, there are theories that logging increases instability in the soil and can result in a sudden collapse and landslide.

Earthquakes are another possible trigger, so regions near a fault line may be at risk of a landslide.

But there are ways you can spot a risky situation with your own eyes. According to the United States Geological Survey, if you see springs or saturated ground in areas that have not been wet before, that’s a warning sign.

Generally, signs of the ground moving are bad, even if the changes seem slight. Cracks and bulges in the ground that suddenly appear should also be noted, as well as soil moving away from foundations. Broken water lines, slanting telephone poles or trees, and sunken road beds are also potential signs.

If you see signs that concern you, contact local officials and ask them to check it out.