An electromagnetic pulse (EMP) is a burst of electromagnetic radiation that can be generated by either a nuclear explosion or a solar flare. The resulting rapidly varying electric and magnetic fields can cause current and voltage surges that can be damaging to electrical and electronic systems. Nuclear EMPs are more energetic and have a shorter burst than solar flares, which range in intensity from causing a bright “Northern Lights” to destroying part or all of the power grid. In military terminology, a nuclear warhead that detonates tens or hundreds of miles above the Earth's surface is known as a high-altitude electromagnetic pulse device (HEMP). The enormous potential of an electromagnetic pulse emitted by the high-altitude detonation of a nuclear weapon has long been recognized.
But it turns out that the real effects of an electromagnetic pulse in outer space on the power grid are strongly determined by the three-dimensional distribution of the rocks under our feet. The gamma pulse traveling outwards propagates at the speed of light, producing a radiated electromagnetic signal. During the first nuclear test in the United States, on July 16, 1945, electronic equipment was protected because Enrico Fermi was waiting for the electromagnetic pulse. The Bluegill Triple Prime and Kingfish high-altitude nuclear tests provided data clear enough to allow physicists to accurately identify the physical mechanisms behind electromagnetic pulses. A new study has identified vulnerabilities to EMP attacks, and the EMP Commission has sponsored a global survey of foreign scientific and military literature to assess the knowledge and intentions of foreign states regarding such attacks. In July, Chinese researchers urged their government to increase the country's readiness to defend itself against a high-altitude EMP attack. The characteristics of a nuclear EMP event vary depending on the altitude of the detonation, while solar eruptions can last much longer than nuclear EMPs.
The fact that a nuclear explosion produces an electromagnetic pulse was already known in the early days of nuclear weapons testing. It is important for governments, businesses, and individuals to understand the differences between nuclear and solar EMPs in order to be prepared for any potential attack. Governments should take steps to protect their citizens from both types of EMPs by investing in research and development into protective measures such as hardening infrastructure against EMPs. Businesses should also take steps to protect their assets from both types of EMPs by investing in protective measures such as surge protectors and uninterruptible power supplies. Individuals should also be aware of the differences between nuclear and solar EMPs and take steps to protect their personal electronics from both types of EMPs. This can include investing in surge protectors, uninterruptible power supplies, and other protective measures.