June 10, 2014

Hypothetically Speaking: Using Scenarios to Anticipate the Unanticipated

Posted by kcompton

Kris Ludwig, Staff Scientist, US Geological Survey Natural Hazards Mission Area

We all use some form of hypothetical situations to plan our daily lives: What if it rains? Bring an umbrella. What if you’re in an accident? Buy insurance. What if there’s traffic? Learn alternate routes. On some level, we understand and accept the risk of discrete events like a storm, an accident, or a travel delay that may adversely affect our plans. Correspondingly, we prepare

Example Chain of Consequences Credit: Department of the Interior, 2013

Example Chain of Consequences
Credit: Department of the Interior, 2013.

But what if the rain causes an accident, jamming traffic – and then the roads flood, stranding travelers and limiting access by emergency personnel? How does one anticipate – and prepare for – a plausible chain of consequences, where each event may lead to another, adding complexity and uncertainty at every step?

Scenarios can be powerful tools for anticipating the unanticipated. Used by the military, public health, natural resource, utilities, and emergency management communities, scenarios can improve preparation for, response to, and recovery from catastrophic events.

What is a Scenario?

The term “scenario” means different things to different users. Scenarios are typically developed by teams of stakeholders at various scales, for multiple audiences, and using many methods. Scenario outcomes may be used for different purposes including informing evacuation plans, improving supply mobilization, or shaping recovery plans. Examples of several types of scenarios include:

Chains of Consequences

The Department of the Interior’s Strategic Sciences Group (SSG) develops chains of consequences stemming from an environmental crisis event. Like a tree diagram, these cascades effectively “map out” possible impacts across the ecology, economy, and people of an affected region. Each consequence is assigned a level of uncertainty, informed by a group of experts assembled by the SSG in response to an event. Analyses of these chains are used to develop interventions, institutional actions that may mitigate downstream effects, for decision makers.

Table Top Exercises

Table Top Exercise Credit:  Photo courtesy of NIH

Table Top Exercise
Credit: Photo courtesy of NIH

Table Top Exercises (TTX) are discussion-based sessions where personnel share what their roles, responses, and concerns would be during a specific situation. Recently, the National Institute of Environmental Health Sciences, part of NIH, developed a TTX to practice the coordination of public health research in the aftermath of a hypothetical tsunami disrupting southern California. Participants included health officials, geoscientists, emergency managers, and community representatives. The outcomes are helping shape the new NIH Disaster Research Response Project, which aims to improve environmental health disaster research by developing data collection tools and a network of trained responders.


Analyses of Hypothetical yet Plausible Events

The US Geological Survey (USGS) Science Applications for Risk Reduction (SAFRR) project has developed several scenarios including ShakeOut, ARkStorm, and a California Tsunami Scenario. Each project aims to improve resilience to natural hazards by developing partnerships among scientists, decision makers, emergency managers, and community leaders to assess the impacts of a hypothetical but plausible event. SAFRR has forged collaborations with artists and designers to develop maps, animations, and videos to communicate scenario results to broad audiences.

Scenario Strengths and Caveats

Two often-heard comments in the emergency management community have special relevance to scenarios:

The disaster that happens is the one you did not prepare for.

An emergency is the worst time to exchange business cards.

These statements highlight both an important caveat and a vital strength of scenarios: they are not intended to predict the future, nor are they meant to preclude necessary creativity when responding to an actual event. Rather, scenarios and exercises can build critical “muscle memory,” foundational knowledge, and valuable relationships that improve our ability to respond to and recover from catastrophic events, ultimately improving resilience.

Scenarios Require a Whole Community Approach

We live in a system of systems, where our energy, telecommunications, transportation, and other lifelines are increasingly interdependent. Intertwined with these services are our economy, social infrastructure, and natural environment. When one or more dimensions of this coupled human natural system are disrupted, others may be affected. These events quickly – and often painfully – reveal vulnerabilities that may or may not have been previously known.

Scenarios are one way to identify these vulnerabilities before a disaster occurs. Because of the multi-disciplinary nature of hazards, effective scenarios require a “whole community” approach, where natural and social scientists, engineers, emergency managers, and policy makers are all invested in the development and implementation of scenario outcomes to improve resilience.


Kris Ludwig is a Staff Scientist in the Natural Hazards Mission Area of the US Geological Survey (USGS), where she supports both the Department of the Interior Strategic Sciences Group and the USGS Science Applications for Risk Reduction project. She has a PhD in Oceanography from the University of Washington and a BS in Earth Systems from Stanford University. Dr. Ludwig will be a panelist at the 2014 AGU Science Policy Conference.