In addition to amplitude, perhaps an event's cause[s], effect[s], duration, and frequency might be useful descriptors.
Causes, such as: manmade, weather-caused, seasonal-hazard, known geological, as-yet-unknown, etc.
Effects, such as: inconvenience, permanently altering, as-yet-unknown, public health hazard,
Duration, such as: matter of seconds, minutes, hours, days, weeks, months, as-yet-unknown,etc.
Frequency, such as: annually, once in a decade, 100-year event, etcetera.