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Understanding Disaster Levels and Alerts

April 9, 2024

In 2022, there were 18 climate disasters in the U.S. that caused over $175 billion in damage. Government disaster alerts and classifications can help protect life and minimize damage. Various organizations and government officials rely on disaster classification systems to determine the necessary preparation and recovery level.

To learn more, check out the infographic created by Tulane University’s Master of Public Health – Disaster Management.

Types of Disasters and Alerts

Recognizing the various types of disasters that may occur in the U.S., and utilizing the proper emergency alerts, can help officials improve communication with the general public and prevent losses.

What the Numbers Say           

According to Forbes, “Between January 2013 and January 2023, 88.5% of all U.S. counties declared a natural disaster, including 95% of the 200 most populated counties.”

In 2022, Hurricane Ian caused $112.9 billion in damage. In total, 2022 had 11 severe storms costing $22 billion, three tropical cyclones costing $117.6 billion, one drought costing $22.4 billion, one winter storm costing $4.8 billion, one wildfire costing $3.2 billion, and one flood costing $1.5 billion.

U.S. Disasters and Alert Systems           

The two types of disasters are manmade hazards and natural disasters. Manmade hazards include hazardous material releases and spills, acts of terrorism, and nuclear accidents. Natural disasters are classified as land-based, water-based, atmospheric, biological, extraterrestrial (a comet strike, for example), or a combination (e.g., an earthquake that also leads to a tsunami).

Americans may receive a few different types of alerts warning of disasters. Wireless Emergency Alerts (WEAs) are short emergency alerts sent by alerting authorities through the Integrated Public Alert and Warning System from the Federal Emergency Management Agency (FEMA). They are designed like text messages and make a unique sound and vibrate twice.

The Emergency Alert System (EAS) is a national public warning system used by the President within 10 minutes of a national emergency. It is also used by alerting authorities to deliver emergency information about local incidents such as weather, potential threats, and AMBER alerts. EAS is sent through TV and radio, satellite digital audio services, wireless cable systems, and cable television systems. It is used when all other public alert methods are unavailable.

The National Weather Radio (NWR) is a national network of radio stations that broadcast weather updates and other hazard information. It also broadcasts non-weather emergencies and threats through EAS. 

The Integrated Public Alert and Warning System (IPAWS) is FEMA’s national system for local alerting, allowing local authorities to send their own emergency alerts without FEMA review or approval. It provides the ability to send EAS alerts, WEAs, and messages through NOAA weather radios, and alerts through digital billboards and sirens. 

Lastly, the FEMA mobile app provides weather and emergency alerts in real time from the National Weather Service. It lists local shelter locations for evacuation, determines location eligibility for FEMA assistance, finds designated Disaster Recovery Center locations, and reads answers to frequently asked questions.

Disaster Level Classification Systems

Though there isn’t a single classification system that is used to define disasters, various factors are considered when measuring their impact.

How Disasters May Be Classified              

Disasters may be classified according to the event that triggered the disaster. A geological event may include earthquakes, volcanic eruptions, and landslides. Biological events include epidemics and epizootics, which are disease events in animal populations akin to an epidemic in humans. A meteorological-hydrological event includes storms, floods, and droughts. 

Disasters may also be classified according to the time it takes for the triggering event to result in disaster. A rapid onset disaster includes earthquakes and hurricanes, while a slow onset disaster includes environmental degradation, such as desertification, sand drifts, and sea-level rise.

When classifying a disaster, the consequences of a disaster may also be considered. Demographic effects include increased mortality rates or reduced fertility, while physical effects include damage to buildings, machinery, land, and more. The economic effects of a disaster result from physical damage or due to destruction of livelihood. Social and political effects include social polarization, unrest, or community/societal upheaval. 

Determining the Scale and Scope of Disasters      

Scope refers to the effect of a disaster on everyday life, while scale refers to the magnitude, intensity, or spread of disaster effects. Parameters that may be used to measure the scale of a disaster include death toll, material losses, injuries, stress on infrastructure, total population affected, evacuation numbers, and damage costs.

Preparing and Responding to Disaster

FEMA, which is responsible for educating the public about disaster preparedness and leading the national response to public safety threats, offers the following tips for disaster preparation.

How to Prepare Before a Disaster               

To prepare for a disaster, sign up for alerts and warnings. Study evacuation routes and stock up on supplies, food, and water. Also, take steps to improve home safety and practice emergency drills. Place documents in a safe place and be sure to document and insure property. Lastly, create and test a family communication plan.

The Four Phases of Emergency Management               

The first phase of emergency management is mitigation. This includes actions to prevent or reduce the cause, impact, and consequences of a disaster; for example, constructing permanent barriers or levees to control flooding, and reinforcing fencing.

The preparedness stage involves planning, training, and educational activities for disasters that cannot be mitigated. At this point, it’s important to develop disaster preparedness plans and test plans through drills and exercises.

The third stage, response, occurs immediately after a disaster when normal operations are impacted or suspended. This could mean implementing a disaster response plan and conducting search and rescue operations.

The recovery stage involves trying to restore normal operations and resuming regular activities. The final phase of emergency management could include preventing or alleviating stress-related illnesses and rebuilding damaged structures.

Leading Disaster Response

Public health officials lead the way in disaster preparedness and response. They rely on various factors to determine the category and level of threat, and to educate the public on ways to protect themselves. An education in public health can equip students with the knowledge and skills to join the field and make a positive difference.

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Cambridge University Press, “Disasters and History: The Vulnerabilities and Resilience of Past Societies”

Federal Emergency Management Agency, Emergency Management in the United States

Forbes, “Natural Disaster Facts And Statistics 2023”

Natural Hazards, “A Universal Severity Classification For Natural Disasters”, “A Guide For Alerts And Warnings”, Emergency Alerts