A mudflow or mud flow is a form of mass wasting involving "very rapid to extremely rapid surging flow" of debris that has become partially or fully liquified by the addition of significant amounts of water to the source material.

Mudflows contain a significant proportion of clay, which makes them more fluid than debris flows; thus, they are able to travel farther and across lower slope angles. Both types are generally mixtures of various kinds of materials of different sizes, which are typically sorted by size upon deposition.

Mudflows are often called mudslides, a term applied indiscriminately by the mass media to a variety of mass wasting events. Mudflows often start as slides, becoming flows as water is entrained along the flow path; such events are often called flow slides.

Other types of mudflows include lahars (involving fine-grained pyroclastic deposits on the flanks of volcanoes) and jökulhlaups (outbursts from under glaciers or icecaps).

A statutory definition of "flood-related mudslide" appears in the United States' National Flood Insurance Act of 1968, as amended, codified at 42 USC Sections 4001 and following.

Mudslides are occassioned when heavy rains or flooding saturate sloping ground and soil layers to the point where the top surface detaches from the lower firmaments and slides in an avalanche type movement.
In Tegucigalpa, Honduras, entire neighbourhoods had been swept away by floodwaters and mudslides. Bodies poked through the mud as residents looted unprotected stores. Dozens of people trapped on roofs waved clothes and shouted for help.
Broader Problems:
Problem Type:
J: Problems Under Consideration
Societal Problems Emergencies
Related UN Sustainable Development Goals:
GOAL 13: Climate Action
Date of last update
02.07.2018 – 10:27 CEST