Landslides and Mudflows: What You Should Know to Stay Safe
Landslides and mudflows can happen suddenly and cause serious damage to property and pose risks to lives. While some move slowly and cause gradual damage, others can happen rapidly, sweeping away everything in their path in just moments.
Understanding what causes landslides and how to recognize warning signs can help you protect yourself, your family, and your neighbors.
What Is a Landslide and Why Is It Dangerous?
A landslide is a rapid movement of a large amount of earth, rock, or debris down a slope. They often occur after heavy rain or rapid snowmelt, which soaks the soil and makes it unstable. Landslides can also be triggered by wildfires that damage vegetation that normally stabilizes the land.
Debris flows—also called mudslides, mudflows, lahars, or debris avalanches—are fast-moving landslides that can carry away trees, rocks, vehicles, and even buildings. They usually start on steep hillsides and can reach speeds of over 35 miles per hour, spreading debris across broad areas.
Major hazards include:
Sudden destruction of property
Damage to roads and infrastructure
Injury or death to people caught in the flow
Amplified flooding if landslides block rivers or streams
Where Are Landslides Most Likely?
Areas at higher risk for landslides include:
Places with a history of previous landslides
Steep slopes and hillside areas
Drainage channels and stream banks
Developed hillsides with septic systems or loose soil
Signs of potential landslide risk include:
Small landslides or shifting soil
Tilted trees or fences
Cracks or bulges in slopes or hillsides
Water rushing or converging in unusual ways on slopes
How You Can Stay Safe
1. Learn the History of Landslides in Your Area
Find out if landslides have occurred before nearby.
Know if your neighborhood is built on or near unstable slopes.
2. Recognize Warning Signs
Unusual sounds like cracking or rumbling coming from a slope.
Sudden or increasing flow of water on slopes or in drainage areas.
Small slides or tilting trees and structures.
3. Be Prepared and Take Action:
If you notice signs of potential landslides, seek a professional assessment to evaluate the risk and possible mitigation options.
Avoid construction or heavy activity on or near unstable slopes.
Clear stormwater drainage paths regularly to prevent water from pooling and increasing soil instability.
Reinforce slopes or retaining walls if recommended by experts.
4. During a Landslide or Mudflow:
If you are in an area prone to landslides, evacuate immediately if you see signs of movement or receive an evacuation warning.
Move to higher ground away from slopes, streams, or areas where debris or mud might flow.
Do not attempt to cross mudflows or debris during an event.
After a Landslide or Mudflow
Stay away from damaged slopes, debris, or unstable ground.
Avoid downed power lines and report hazards.
Check on neighbors—especially seniors or those with mobility issues.
Be cautious of additional slides or aftershocks that can trigger new landslides.
Document damage for insurance purposes once it is safe to do so.
Myths About Landslides
Myth: Landslides only happen in mountain areas.
Fact: Landslides can occur in any area with slopes, including hills, urban areas, and even some flat regions with loose soil.Myth: Heavy rain always causes landslides.
Fact: While rain increases risk, landslides can happen with little warning if slopes are already unstable.Myth: You can stop a landslide by building barriers or walls.
Fact: Barriers can reduce damage but cannot fully stop a landslide if the slope is severely unstable. Always seek professional advice.
Remember: Stay Calm and Stay Informed
You don’t need special training to keep yourself safe. Recognizing signs of potential landslides, evacuating early if needed, and following official instructions are your best tools. Regularly review your safety plan and help your neighbors prepare.
Together, we can protect ourselves and our community from landslides—until professional responders arrive.