OEAS 250N: Natural Hazards and Disasters

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Courses: OEAS 250N (CRN 16159); class 4 credits; and OEAS 250N (CRN 16163), lab 0 credit
Course title: Natural Hazards and Disasters
Instructor: Dr. Hans-Peter Plag
Office Hours: Mondays, 2:00-4:00 PM (by Zoom; Go to Office hour) and on request (mostly by Zoom; send request by email to Plag to get the Zoom link).
TA: Kelly Jones
Term: Fall 2020, August 29 - December 18, 2020
Time: Thursdays, 4:20 PM - 7:00 PM (class)
  Thursdays, 7:10 PM - 8:00 PM (lab)
Location: Zoom Meetings (URL in workspace)


The course introduces some of Earth's natural phenomena that can, and often do, result in major loss of life or catastrophic damage to property. These phenomena are considered in their relevance to major national and international efforts to manage and reduce disaster risk and increase societal sustainability. Students in the classes and labs develop and enhance their research, analysis, critical thinking, and writing skills. The course is suitable for first and second year undergraduate students considering a career in science, teaching, and governance, or who are just interested to know more about the planet on which they live.

On Natural Hazards and Their Relationship to Disasters

Although the class and lab are titled “Natural hazards and disasters,” it needs to be emphasized that the distinction between natural and anthropogenic hazards is somewhat arbitrary. It would work if humans were in a spaceship and Earth was free of humans. The fact that humanity is an integral part of the ELSS and is modifying the ELSS at a very significant level leads to many hazards that seem to be “natural” but are actually to some extent caused or amplified by humans.

The boundary between hazards of non-human and human origin is blured. Technological hazards can be triggered by non-technological hazards. Human activity can trigger hazards or change the spectrum of hazards in terms of frequency and magnitude. Human activity can also lead to the ELSS crossing thresholds and entering new states with significantly different characteristics and mal-adaptation. The interdependency of human and non-human hazards will be discussed in detail.

Hazards and disasters are linked by processes in the exposed community and its environment that are triggered by a hazardous event. These processes depend on how the community is organized and developed, and the same hazardous event can lead to a wide range of disasters depending on the exposed community's preparedness and adaptation. Understanding the processes that link hazards and disasters is a prerequisite for Disaster Risk Governance (DRG). The class will analyze these processes based on case studies.

Humanity is embedded in, and interacts with, the Earth's life-support system (ELSS). The ELSS provides the basis for the welfare of all human and non-human communities, and these communities are adapted to prevailing conditions. Hazardous events can change these conditions and cause damage to the communities, with the impacts ranging from local, individual to global scales. For humans, reducing disasters caused by hazards is a goal and a necessity to improve sustainability of human communities. Disaster reduction, or better, DRG, requires a thorough understanding of the hazards that can occur, the probability of them occurring, and the processes that can lead to disastrous impacts on human and non-human communities.

In the interaction with the ELSS, humans have to make choices about where to settle, how to develop communities and the built environment, how to meet the needs of human communities, and how to prepare for hazardous events. Many of these choices benefit from a risk-based decision-making. For many of the non-human hazards, we cannot change very much the “Probability Density Function” (PDF) of the hazards, but we can impact vulnerability and exposure of human communities. The concept of DRG captures this.


[2019/08/16] All registered students should have acces to the Web workspace. If you encounter problems in accessing the Web workspace, please inform the instructor by email.

Basic Concepts

In the class and lab, we define a hazard as a change of the system state that can lead to a reduction of the system's capability to function. A hazard can be a short event (e.g., an earthquake), a longer process (e.g., extinction), or a slow trend (e.g., sea level rise). We distinguish:

  • extraterrestrial hazards: asteroids, bolides, radiation events, and solar storms
  • geo(logical) hazards: those that arise mainly from processes in the solid earth;
  • hydro-meteorological hazards: those that are associated with processes in the coupled hydrosphere-atmosphere system;
  • biological hazards: pandemics, rodents, insects, algae-bloom, extinction;
  • chemical hazards: changes in major flows of the ELSS leading to changes in the composition of atmosphere, ocean, soil, water (including pollution, acid rain, ocean acidification, change of greenhouse gases);
  • technological hazards: accidents, mal-function, AI, nano-technology;
  • social hazards: involuntary migration, unrest, racism, genocide, wars, imperialism, failed governance
  • economic hazards: depressions, bubbles, speculations, peak-oil, etc.

The course introduces these hazards and discuss their direct and indirect relevance for human and non-human communities. Main focus will be on hazards with pre-dominantely non-human origin. However, in the Anthropocene, humanity increasingly causes changes in the PDF of hazards. For example, anthropogenic changes in the chemistry of the atmosphere cause unprecedented cliamte change, which has a large impact on the PDFs of almost all hydro-meteorological hazards. The extinction of species and changes in the flows of chemical constituents impacts the PDF of many biological hazards. The major anthropogenic modifications in the physiology of the ELSS blures the line between natural and anthropogenic hazards.

A useful concept for assessing the relevance of hazards is “Risk”. Risk associated with a specific hazard is defined as the product of hazard probability, vulnerability and value of the assets exposed to the hazard. Many efforts aim at reducing the risk, or better governing the risk. The class will introduce the concept of DRG and apply this concept to case studies.

At the core of understanding the potential of a hazard to cause disasters is the PDF of the hazard. Both the classes and labs will be used to go into more details about the PDFs of the different hazards.

Disaster risk assessments are an important tool to guide community actions to reduce or govern the risk. However, public and governmental support for DRG depends on risk awareness, which is determined by individual, community, country and cultural biases. In modern societies, the media play an important role for the development of, as well as the biases in, risk awareness. The class will review a number of risk assessments and relate them to risk awareness. The role of the media in shaping risk awareness will be analyzed.