How not to cheapen the impact of the calamities by adding words? A horrible day in which a mortar attack on a religious procession led to hundreds of deaths, days in which hurricanes and floods led to hundreds of deaths.
No tragedy in this world has a single cause. In Iraq, it is occupation, war, terror, strategies of power that are contemptuous of human life and human tolls. In the US South, it is weather; but it is also probably the changing climate, and poverty, and exclusion, and the misallocation of resources, things that will only get worse as the 'reconstruction' happens - as occurred with the tsunami in Asia.
To the degree they are human caused, tragedies are preventable and, more importantly, future tragedies can be avoided.