Disaster: 1. A serious disruption of the functioning of a community or a society causing widespread human, material, economic or environmental losses which exceed the ability of the affected community or society to cope using its own resources (ISDR). 2. Situation or event, which overwhelms local capacity, necessitating a request to national or international level for external assistance (CRED).
World Health Organization: http://www.who.int/hac/about/definitions/en/
Public health management of disasters. by
The third edition of this landmark book consolidates and updates important information on disaster-related resources into one source. It is designed to help the public health profession plan for tasks for which "on the job" is the chief teacher.
Social media use in crisis and risk communication. by
This book is about how different communicators - whether crisis managers, first responders, journalists, or private citizens and disaster victims - have used social media to communicate about risks and crises. It is also about how these very different actors can play a crucial role in mitigating or preventing crises. Chapters address such questions by presenting new research-based knowledge on social media use during different crises: the terrorist attacks in Norway on 22 July 2011; the central European floods in Austria in 2013; and the West African Ebola-outbreak in 2014. Social Media use in Crisis and Risk.