Electromagnetic pulses (EMPs) are extreme electromagnetic incidents caused by an intentional electromagnetic pulse. EMPs are generally associated with intentional attacks using high-altitude nuclear detonations, specialized conventional munitions, or non-nuclear directed energy devices. Effects vary in scale from highly local to regional to continental, depending upon the specific characteristics of the weapon and the attack profile. High-altitude electromagnetic pulse attacks using nuclear weapons are of most concern because they may permanently damage or disable large sections of the national electric grid and other critical infrastructure control systems. Depending on the nature of the attack, cascading failures of major infrastructure and related industry could result. Damage could spread through the electric power infrastructure and into telecommunications, energy, and other infrastructures. This cascading damage would seriously impact other important aspects of life such as means of getting food, water, and emergency care to the general public.

While often discussed simultaneously, geomagnetic disturbances (GMDs) and EMPs are distinct disaster events. Extreme GMDs are associated with solar coronal mass ejections and can cause widespread and long-lasting damage to electric power systems, satellites, electronic navigation systems, and undersea cables. A coronal mass ejection (CME) – sometimes called a “solar EMP" – is a large ejection of plasma and magnetic field from the sun. These ejections can then be carried into space on "solar winds", the continuous flow of charged particles from the sun. CMEs are a daily occurrence and, in most cases, have no effect on the Earth. But if a sufficiently large CME hit the Earth’s magnetosphere, it could cause similar disruptions to electricity as a weaponized EMP. Space weather phenomena are relatively well understood within the scientific community, but the historical rarity of extreme GMD events limits the availability of data useful for predictive analysis. When a geomagnetic storm induces transmission lines with additional, unregulated current, but the output of voltage stays the same, mechanical failures can occur, causing large power outages and damage in seconds. Geomagnetic storms can result in widespread electrical failures, though most electric power companies have procedures in place to mitigate the impacts of these storms. However, the precise nature of these procedures and the technology in place are closely guarded company information for obvious security reasons.

Any comprehensive regulatory or legislative approach to mitigating or preventing damage from an EMP or GMD incident is largely a task for the federal government. The most recent federal action related to EMPs was an executive order issued by President Trump on March 26, 2019 directing several agencies to immediately undertake numerous studies and reviews related to improving the nation's resilience to the effects of EMPs. While the Department of Homeland Security, the Federal Energy Regulatory Commission, and the Department of Energy have primary responsibility to protect against a potential EMP or GMD incident there are still numerous potential actions that states could take in order to harden themselves against the potential effects of an incident. This report will detail several approaches Virginia could take to prepare for and mitigate the effects of an EMP or GMD incident.