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Landslide susceptibility in California

The California Geological Survey publishes a statewide map of how susceptible land is to deep-seated landslides. This guide explains what it shows, what it leaves out, and how to view it, along with slope and elevation, on Outpost’s free map.

Data as of October 23, 2026; refreshed monthly.

In short

Screening only — not a legal or official determination. Verify with the issuing agency.

What Map Sheet 58 shows

Map Sheet 58 estimates the relative likelihood of deep-seated landslides across California. It combines the strength of the underlying rock with the steepness of the slope: weak rock on steep slopes ranks highest. Mapped past landslides are treated as the weakest material, so on steep ground they fall in the highest classes (CGS’s digital landslide inventory covers only some counties). The classes run from 0 to X in Roman numerals; CGS calls classes VIII to X very high.

It shows where the ground is susceptible, not when a slide might happen. Heavy rain, earthquake shaking, grading and drainage all play a part at a real site.

After a wildfire

Burned slopes can produce debris flows during intense rain, a fast-moving shallow hazard that Map Sheet 58 doesn’t cover. The U.S. Geological Survey publishes debris-flow hazard assessments for many recent fires. See the fire hazard guide for the fire perimeters Outpost shows.

How to check a location on Outpost

  1. Open the map, then search an address or click a point on it.
  2. The scorecard’s landslide row reads the map color at the point from CGS’s own published map tiles, at the moment you check, and groups it into five levels from very low to very high. The levels are Outpost’s grouping of CGS’s 0 to X classes, so they may not line up exactly with CGS’s own wording. The top two levels are highlighted.
  3. Where high susceptibility overlaps a recent fire perimeter or a mapped fire hazard area, the scorecard adds a debris-flow note. That note is Outpost’s own combination of the two maps, not an agency rating; for post-fire debris flows, use the USGS assessments.
  4. The Land section shows the elevation and slope at the point from the USGS 3D Elevation Program, plus a short terrain profile. Slopes steeper than 25° are highlighted.
  5. To see the map itself, turn on the Landslide Susceptibility layer in the sidebar.

What Outpost can’t tell you

Open the mapFree, no account. Search an address or click any point in California.

Common questions

Is there a landslide map for California?

Yes. CGS Map Sheet 58 covers the whole state for deep-seated landslides. CGS also keeps a landslide inventory and, in some areas, regulatory earthquake-induced landslide zones. Outpost shows Map Sheet 58.

Can I use the landslide map for one property?

No. CGS says Map Sheet 58 isn’t for judging landslide potential at a particular location. It is a regional overview; a licensed engineering geologist or geotechnical engineer evaluates a specific site.

Does it include mudslides or debris flows?

No. It is about deep-seated landslides. For debris flows after a wildfire, see the USGS post-fire debris-flow hazard assessments.

What makes an area more susceptible?

Weak rock, steep slopes and past landslides. Water, earthquake shaking and grading can then set a slide off.

Official sources