What is the difference between a primary and a secondary effect of a natural disaster?

In the case of a natural disaster, there will be a whole range of effects. The simplest way to distinguish between these effects is to categorise them as primary or secondary. A primary effect is one that is directly caused by the disaster, is an integral part of the disaster itself; in the case of an earthquake, it would be the ground shaking, or in the case of a volcanic eruption, lava pouring out of the volcano. A secondary effect will then happen as a result of this; a mudslide cascading down the side of the slopes of the volcano from the rising lava for example. In the case of an earthquake, a secondary effect is collapsing buildings because of the ground shaking.