Winter Landslide Warning Signs Around Your Property

The short version

• Learn your property's baseline before winter so you can spot what's new. One odd crack can be nothing; a cluster, or anything getting worse during a storm, is a warning.
• Watch for movement: new ground cracks or bulges, soil pulling away from foundations, tilting trees and fences, sticking doors, new seeps or saturated ground, a creek that suddenly runs muddy, and rumbling or cracking sounds.
• Active movement or an imminent slide: leave immediately and call 911. Don't stop to investigate or grab things.
• Below or near a CZU burn scar: treat a Flash Flood Warning as an evacuate-now alert, and know your evacuation zone before the season starts.
• This is a homeowner's guide to noticing trouble early, not a substitute for a professional geologic assessment.

When heavy winter rain settles over a forested slope in the Santa Cruz Mountains, the ground you live on can start to move, and that risk rises sharply during and after the storm, especially below hillsides burned in the CZU fire. The reassuring part is that many slides give warning signs before they let go, and knowing what to look for can buy you time to act. This isn't a substitute for a professional geologic assessment; it's a homeowner's guide to noticing trouble early. If the ground is actively moving or a slide looks imminent, don't investigate. Leave and call 911.

What to watch for

The U.S. Geological Survey and slope experts point to a consistent set of warning signs. Around your home and yard, watch for:

• New cracks or bulges in the ground, pavement, driveway, or the base of slopes.
• Soil or fill pulling away from foundations, decks, or stairs, or new gaps opening up.
• Tilting or leaning trees, fences, retaining walls, utility poles, or decks that were straight before.
• Doors or windows that suddenly stick or jam, or new cracks in walls, foundations, or tile, a sign the structure is shifting.
• Water showing up where it didn't before: new springs or seeps, unusually saturated ground, or water breaking out of a hillside.
• Changes in a creek or drainage: water that suddenly turns muddy, or flow that rises or drops sharply, can signal movement upstream.
• Sounds: faint rumbling, cracking, or trees popping, which can grow louder as movement increases, is a reason to get out now.
• Cracking or bulging retaining walls, or a wall that's begun to lean.

Any one of these can have an innocent explanation. A cluster of them, or any that are getting worse during a storm, deserves serious attention.

What to do if you see the signs

• If movement is active or a slide seems imminent (ground shifting, growing cracks, rumbling), get everyone out of the path immediately, if it is safe to do so, and call 911. Don't stop to gather things. If debris is already hitting the building you're in, the U.S. Geological Survey says not to go outside: get to the highest floor, or up onto something solid, and stay there.
• If you notice worrying but not active signs, keep people away from the area, document them with photos, and consult a geotechnical or geologic professional. On a county road or right-of-way, report it to the county.
• Reduce your exposure ahead of storms. Know which rooms and which side of the house are most exposed to an uphill slope. During a storm that could cause a slide, the National Weather Service's advice is to stay alert and awake rather than to sleep through it, because many landslide deaths happen while people are asleep. If you have real concerns about your slope, leave before the storm rather than waiting it out.

The burn-scar factor

Hillsides burned in 2020 shed water fast and are more prone to debris flows, fast and destructive slurries of mud, rock, and trees, during intense rain. The alert to watch for is a Flash Flood Warning: that is the product the National Weather Service issues for this hazard, there is no separate "debris-flow warning," and it can arrive with very little lead time. If you live below or near a burn scar, treat one as an evacuate-now alert, and know your evacuation zone before the season.

Before and after storms

Before winter, walk your property and note the baseline so you can spot changes. Clear culverts and drainage so water doesn't saturate a slope unnecessarily. After a big storm, walk it again, and remember that ground can keep moving for days after the rain stops, part of what to do after a major storm.

Frequently asked questions

What are the warning signs of a landslide?

New ground cracks or bulges, soil pulling away from foundations, tilting trees or fences, sticking doors and new wall cracks, new seeps or saturated ground, sudden muddy or changed creek flow, and rumbling or cracking sounds. A cluster of these, or any worsening during a storm, is a warning.

What should I do if I think a slide is starting?

If the ground is actively moving or a slide looks imminent, leave immediately, as long as leaving is safe, and call 911. If debris is already striking the building, don't go outside; get to the highest floor. For worrying but non-active signs, keep people away, document them, and consult a geologic professional.

Why is Boulder Creek at higher landslide risk?

Steep, forested slopes plus heavy winter rain, and hillsides burned in the 2020 CZU fire that shed water and can produce debris flows. Risk peaks during and just after big storms.

Last reviewed July 20, 2026. This guide draws on official guidance from the U.S. Geological Survey and the National Weather Service. It is not a geologic assessment.

For active danger, call 911. For forecasts, watch the National Weather Service, and for local road and slope conditions before you travel, check Mountain Status.