Sliding plate boundaries
Transform motion is mainly horizontal. It transfers movement along the plate network without creating a ridge of new crust or consuming a plate in a trench.
BOUNDARIES
Explore an example
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Plate colours identify regions, not risk.
Oceanic transforms
Active oceanic transforms often link offset ridge segments. Fracture zones continue beyond them as older seafloor structures; the full length of a fracture zone is not an active plate boundary.
The San Andreas example
The San Andreas is a major part of the Pacific-North American boundary in California. Movement is shared across a wider fault system, including faults beyond the main San Andreas trace.
Sources and map method
Plate outlines use Peter Bird's PB2002 model, distributed by Nordpil under the Open Data Commons Attribution licence. Coastlines and country outlines are Natural Earth public-domain data. Boundary detail is limited by the source model.
- USGS: Understanding plate motions
- USGS: Oceanic transform faults and fracture zones
- California Geological Survey: Faulting in California (2018)
- Map dataset sources and licences
- PB2002 geometry and licence
- Natural Earth terms
Country lookup compares simplified land outlines with the plate model. Boundaries and historical coastlines are modelled features. This atlas explains geography; it does not predict earthquakes or provide site-specific hazard estimates.