EMP

An electromagnetic pulse (EMP) is a burst of electromagnetic energy that can disrupt or damage electrical and electronic systems. EMPs can be natural or man-made. They are typically described in terms of their time profile and source, and they may affect power grids, communications, and sensitive electronics.

Natural EMPs arise from space weather and atmospheric phenomena. Geomagnetic storms driven by solar activity can induce currents in long conductors such as power lines, potentially harming transformers and grid stability. Solar flares can cause rapid changes in ionospheric conditions, affecting radio communications and navigation systems. A historically notable instance is the 1989 geomagnetic storm that caused widespread power outages in Quebec and affected other regions.

Man-made EMPs are produced intentionally or as byproducts of nuclear or conventional devices. Nuclear detonations at high altitude generate a high-altitude EMP (HEMP) with three distinct components: an ultra-fast E1 pulse that can disturb or destroy electronics, a slower E2 pulse similar to lightning, and an even slower E3 pulse that induces sustained currents in long conductors. Non-nuclear EMP devices can produce localized pulses and are generally more limited in reach but can still affect nearby equipment.

Effects of EMPs range from brief electronic glitches to permanent damage of semiconductor devices, protective relays, and grid infrastructure. Highly energized transients can disrupt communications, GPS, and control systems, with cascading impacts in critical industries.

Protection and mitigation efforts focus on hardening essential equipment and networks: shielding and grounding, surge suppression, redundant systems, and protective architectures. Standards and guidelines for EMP resilience are used in military and civilian sectors to reduce vulnerability and speed recovery after an event.