> Starfish Prime caused an electromagnetic pulse (EMP) that was far larger than expected, so much larger that it drove much of the instrumentation off scale, causing great difficulty in getting accurate measurements. The Starfish Prime electromagnetic pulse also made those effects known to the public by causing electrical damage in Hawaii, about 900 miles (1,450 km) away from the detonation point, knocking out about 300 streetlights,[1]: 5 setting off numerous burglar alarms, and damaging a telephone company microwave link.[6] The EMP damage to the microwave link shut down telephone calls from Kauai to the other Hawaiian Islands.[7]
This was a 1 Mt bomb 10x as far from the surface as the article discusses.
It should be understood that the largest impact of the Starfish Prime test, knocking out streetlights, was the result of a very specific design detail of the street lights that is now quite antiquated (they were high-voltage, constant-current loops with carbon disc arc-over cutouts, and the EMP seems to have caused some combination of direct induced voltage and disregulation of the constant current power supply that bridged the carbon disks). The required repair was replacement of the carbon disks, which is a routine maintenance item for that type of system but of course one that had to be done on an unusually large scale that morning. The same problem would not occur today, as constant-current lighting circuits have all but disappeared.
In the case of the burglar alarms, it is hard to prove definitively, but a likely cause of the problem was analog motion detectors (mostly ultrasonic and RF in use at the time) which were already notorious for false alarms due to input voltage instability. Once again, modern equipment is probably less vulnerable.
Many of the detailed experiments in EMP safety are not published due to the strategic sensitivity, but the general gist seems to be along these lines: during the early Cold War, e.g. the 1950s, EMP was generally not taken seriously as a military concern. Starfish Prime was one of a few events that changed the prevailing attitude towards EMP (although the link between the disruptions in Honolulu and the Starfish Prime test was considered somewhat speculative at the time and only well understood decades later). This lead to the construction of numerous EMP generators and test facilities by the military, which lead to improvements in hardening techniques, some of which have "flowed down" to consumer electronics because they also improve reliability in consideration of hazards like lightning. The main conclusion of these tests was that the biggest EMP concern is communications equipment, because they tend to have the right combination of sensitive electronics (e.g. amplifiers) and connection to antennas or long leads that will pick up a lot of induced voltage.
The effects of EMP on large-scale infrastructure are very difficult to study, since small-scale tests cannot recreate the whole system. The testing that was performed (mostly taking advantage of atmospheric nuclear testing in Nevada during the 1960s) usually did not find evidence of significant danger. For example, testing with telephone lines found that the existing lightning protection measures were mostly sufficient. But, there has been a long-lingering concern that there are systemic issues (e.g. with the complex systems behavior of electrical grid regulation) that these experiments did not reproduce. Further, solid-state electronics are likely more vulnerable to damage than the higher-voltage equipment of the '60s. Computer modeling has helped to fill this in, but at least in the public sphere, much of the hard research on EMP risks still adds up to a "maybe," with a huge range of possible outcomes.
LEDs use constant current drivers, though. And even if you disagree, LEDs need to be current limited, so something will break with a large pulse of current, the driver or the LEDs themselves.
the constant-current drivers in LED lighting are a very different concept from constant-current lighting circuits, which are a ~1920s technology rarely seen today. constant-current lighting circuits can be miles long, operate at up to 1kV or so, and require some type of cut-out/bypass feature at each individual light so that a failure of a single bulb does not take the entire circuit out. The problems that constant-current lighting circuits address (maximizing the life of incandescent bulbs) are all solved in different, more robust ways in modern lighting systems. Most significantly, the carbon-disc cutouts that were the direct cause of the street lighting failures are no longer used (even in legacy constant-current lighting systems, where they have been replaced with more modern devices).
> Starfish Prime caused an electromagnetic pulse (EMP) that was far larger than expected, so much larger that it drove much of the instrumentation off scale, causing great difficulty in getting accurate measurements. The Starfish Prime electromagnetic pulse also made those effects known to the public by causing electrical damage in Hawaii, about 900 miles (1,450 km) away from the detonation point, knocking out about 300 streetlights,[1]: 5 setting off numerous burglar alarms, and damaging a telephone company microwave link.[6] The EMP damage to the microwave link shut down telephone calls from Kauai to the other Hawaiian Islands.[7]
This was a 1 Mt bomb 10x as far from the surface as the article discusses.
All that to say, it's plausible.