Hazard – threatens human life and property; the process itself is not a hazard, rather, it becomes a hazard only when
threatening human interests
Risk: probable severity that a destructive event will occur multiplied by the event’s likely impact on people and property;
risk thus integrates hazard and social vulnerability
Disaster: an event that causes serious injury, event that causes serious injury, loss of life, and property damage over a
limited time and within a specific geographic area
Catastrophe = the same as disaster, except that it is more massive and affects a larger number of people and more
infrastructure than disaster [ex. consequences far beyond the area that is directly affected require huge expenditures of
time and money for recovery]
Volcanic explosion at the hot spot or MOR is not violent because they are shield volcanoes and they have basaltic
magma. The violent explosions occur at the subduction zones (converging) because of felsic magma (thick and blocks
gases – violent).
Volcanic hazards – lava flows, tephra aka ash fall (this can block sunlight if ash is sent into the atmosphere and the
plants die, people starve, etc). Climate change (volcanoes send greenhouse gases into the atmosphere which heats the
earth; and they send aerosols which results in cooling of the planet), earthquakes happen, gaseous emissions
Lahars can happen during an eruption or much later and they can be cold or hot and they are concentrated mud flows.
Pyroclastic flows happen only during an eruption and they release very hot gases and they come roaring from the
How do we monitor volcanoes?
Seismic activity (monitor earthquake activity), gas output (change in type or amount of gas coming out), heat flow (if it
getting a lot hotter, magma is closer), topography (checking for bulges, new magma coming out), mudflows/lahars,