## Definition

**Probability of occurence** is the propability of a natural event of a given magnitude being equalled or exceeded in a given period of time. [*1] It refers the chance of occurrence of one event compared to the population of all events. Therefore, probability is dimensionless. It is however, often referenced to a specific time frame, for example, as an annual exceedance probability or lifetime exceedance probability.

## Context

## Methodology

**Probability** can be expressed using:

**probability**: - probability of a particular event
- annual probability of exceedance
- lifetime probability of exceedance

**frequency**: - annual exceedance frequency
- return period

## Example

## Assessment