Geology · Glossary
Landslide
Updated 2026-07-18
Landslide is the downslope movement of soil, rock, or debris under gravity. California landslide susceptibility and seismic hazard maps can flag concern, but site stability requires geologic and geotechnical evaluation.
What it means
Landslides include falls, slides, flows, and complex movements triggered by rainfall, erosion, earthquakes, grading, or other changes.
Why it matters for land decisions
Mapped or observed instability can constrain building sites, roads, drainage, septic areas, and insurability.
- Review terrain and historical mapping.
- Avoid altering drainage without analysis.
People also ask
Does steep slope always mean landslide?
No. Slope is one factor; geology, groundwater, erosion, and past movement also matter.
Are landslide maps definitive at parcel scale?
No. They are screening or regulatory tools with scale limits and should be supplemented by site investigation.
Official sources
Related terms
Check this on a California parcel
Parcel View screens zoning, flood, fire, soils, and planning layers for any California lot — every finding linked to the official source.