The Chixoy-Polochic Fault is a left-lateral strike-slip fault crossing central Guatemala for about 300 kilometres, running roughly east to west parallel to the better-known Motagua Fault to its south. Together they form the on-land plate boundary between the North American Plate and the Caribbean Plate.
The Caribbean Plate slides eastward past North America at around 2 centimetres per year, and the Chixoy-Polochic strand takes up part of this motion. Its trace follows steep river valleys and mountain fronts through the Guatemalan highlands, and geologists have documented tens of kilometres of cumulative displacement of ancient rock formations along it.
The fault is capable of large earthquakes, and it lies within the same tectonic system that produced the devastating 1976 Guatemala earthquake (magnitude ~7.5) on the neighbouring Motagua Fault, which killed more than 23,000 people. The Chixoy-Polochic itself has generated significant historical shaking and remains an important seismic hazard for northern Guatemala.