 Many things humans do can influence natural hazard events. My specialty is in the geological hazards. And so we normally think of particularly the geological hazards as not particularly influenced by human activity, but that's not really true. Earthquakes can be triggered by things like fracking and particularly wastewater injection. Anything that alters the stress field in the interior of the Earth can potentially trigger an earthquake and certainly injecting fluids either for fracking or for trying to dispose of wastewater can influence that stress field and essentially lubricate faults and lead to triggering of earthquakes. The other thing humans do that can influence the earthquake, shaking of the ground, is altering the soil properties. In particular, making areas, trying to fill areas with sort of loose fill that they can then build on. Well that loose fill is particularly prone to earthquake shaking and sometimes to a phenomenon called liquefaction and that can have a very strong influence on the occurrence of ground shaking.