Question

What are the causes behind disaster's strike?
those who give correct answer I will mark it as braibnliest.plz its urgent

Answer 1

Earthquakes, tsunamis, hurricanes, tornados, floods, droughts, wildfires, volcanic eruptions, landslides and avalanches are considered (among others) natural disasters. A natural disaster usually has significant impact on our society directly or indirectly.

For each disaster, there can be several events that lead up to it.

A rather large hillside has been deforested recently. There has been heavy droughts the past couple years and they are now expecting heavy rainfall.

Earthquakes can be caused by the shifting of tectonic plates. Sometimes increased mining in an area, like natural gas drilling, can cause earthquakes.

Volcanoes. They often go hand-in-hand with seismic activity. Things shift around and gasses can often get pent up looking for an escape route. Sometimes explosive and sometimes not so much.

Answer 2

A disaster is an unplanned event in which the needs of the affected community outweigh the available resources. A disaster occurs somewhere in the world almost daily, but these events vary considerably in scope, size, and context. Large-scale disasters with numerous casualties are relatively unusual events. Certain widely publicized disasters, including events such as the terrorist attacks on September 11, 2001, Hurricanes Katrina and Sandy, and the Boston Marathon bombing, have focused people’s attention on disaster planning and preparedness. Disasters are becoming more frequent, and the number of persons affected is also increasing. This greater morbidity is attributable not only to the greater number of events, but also to population dynamics, location, and susceptibilities.

While these incidents have led to an increase in general disaster awareness, the relative infrequency of major catastrophes affecting defined populations leads to a certain degree of complacency and underestimation of the impact of such an event. In the wake of a large-scale event, public attention focuses on disaster planning and preparedness and the resources dedicated to improving response and resiliency surge. This phenomenon has been described as "issue salience" and has then been noted to decline over time as communities return to their quotidian lives. 
1. The result of complacency is relative reluctance to devote the necessary resources for adequate disaster preparedness. Understanding the effects of a serious event on the community may indicate that the best time to propose major changes for disaster preparedness, including funding, is immediately following a widely publicized disaster, even if the event has occurred in a remote location.