written 16 November, 2025
published 23 November, 2025
Black swan events have low probability, but very high impact. Because the frequency, magnitude, and duration of these events are uncertain, it is difficult to plan for resilience, or calculate the cost. However, we can get some information from history.
The Cascadia subduction zone stretches from Ferndale, CA, north into British Columbia, Canada. This is an area of geophysical plate motion where part of the oceanic crust is being forced under the lighter weight continental mass of North America. Subduction zones, due to the physics and scale of the masses involved, produce the largest earthquakes on the planet.
The entire Cascadia fault last ruptured 324 years ago, estimated as a magnitude 9.2 event based on Japanese tsunami records. Geophysical investigation has found that over the last 10,000 years, the entire length has ruptured 20 times, with intervals ranging from 110 to 1,150 years. The southern portion has ruptured twice as often, with intervals ranging from 40 to 720 years. We have now gone longer than 93 percent of the known times between earthquakes in the last 6,000 years.
Large earthquakes make the planet ring like a bell for several days. Seismologists report a Cascadia event could trigger motion on the San Andreas fault. The northern portion under San Francisco hasn't moved since 1906, and the southern portion under Los Angeles hasn't moved since 1857, both were magnitude 7.9 events. A Cascadia/San Andreas combined disaster could affect the entire west coast of the United States, costing hundreds of billions, requiring years to recover.
Beginning in the December, 1861, two strong atmospheric rivers hit both northern and southern California dumping 10 feet of rain over 4 weeks. The central valley was flooded 20 feet deep, which didn't clear out for 6 months. 164 years ago, the area was relatively unpopulated. Such an event today could cost a trillion dollars, displace millions for the duration, and take untold time to recover. These inundations have occurred before, with intervals ranging from 51 to 426 year, some greater than the 1861 flood. On a warming planet, storms carry increasing water content, making inundation events more frequent and extreme.
In September, 1859, the Earth was hit by a strong solar flare: an electromagnetic storm known as the Carrington Event. When a magnetic field passes through a loop of wire, an electric current is induced in the wire. This is why electric motors and generators work. 166 years ago, telegraph systems were just being installed, creating loops of wire many miles long. The solar flare induced such large currents in these loops, that sparks flew from the telegraph keys, and the system was able function without any batteries.
Since then, the national electric grid has been constructed, with many more miles of wire forming loops. If such a flare was to hit the Earth today, the induced currents could blow out the large transformers that are essential to the operation of the grid. A modest geomagnetic storm knocked out power across a wide area of Quebec in 1989. There are about 55,000 transformers in the US grid, and destroying as few as 9 critical ones could black out power across the country. These transformers are all custom built for their specific location, and delivery time is measured in years.
Society today has the expectation of constant electricity, but is dependent on an electrical grid which is ageing, fragile, and occasionally stressed carrying even the normal load, in a world that can change very quickly. Systems that worked before electricity no longer exist, or are unable to carry a civilization of so many people. If electricity went away completely, 90 percent of the population would die.
Any of these three natural disasters, without even considering hostile human activity, could disrupt our electrical supply for an unknown duration. These natural events have already happened, and we know they will happen again.
While atmospheric river and space weather forecasting can give a few days warnings of flooding and solar flares, earthquakes are essentially unpredictable. We could have a quake before you finish reading this article, or not for another century. In the face of this reality, it is prudent to prepare for what is possible, even if we can only lessen the magnitude of the impact. The technology for local power resilience not only exists, but is the cheapest power to install.
Do we have the will to act while we still can?
