Macrozonation
The division of a region or large area into zones that express future hazards, vulnerabilities or risks on the basis of accumulated information about where disasters have struck in the past and what distributed spatial effects they have had. Appropriate scales are 1:50 000 to 1:250 000. See also microzonation.

Man-made disasters
See Human-made Disasters.

Mass movement
A general term for the outward and downward movement of slope-forming material under the influence of gravity, without the assistance of water as a transport agent. Mass movement includes abrupt movements such as landslides, as well as slower, more widespread movements such as creep and subsidence.

Mass wasting
A general term for the reduction of the mass of landforms by downslope transport of soil and rock material brought about by slope processes including mass movement, fluvial, pluvial and wind action.

Mean return period
The average time between occurrences of a particular hazardous event.

Microzonation (microzoning)
Subdivision of a region into areas where similar hazard-related effects can be expected.

Mitigation
Measures undertaken to limit the adverse impact of, for instance, natural hazards, environmental degradation and technological hazards.

Monitor
To check, supervise, observe critically, or record the progress of an activity, action or system on a regular basis in order to identify change.

Monte Carlo simulation
A procedure, which seeks to simulate stochastic processes by random selection of input values to an analysis model in proportion to their joint probability density function.

Mudflow
The rapid and localized downslope transfer of fine earth material mixed with water.

BACK TO GLOSSARY