How do we know about these catastrophes of the past?

Today, the number and intensity of cataclysms on the planet are growing exponentially. Humanity is facing a terrible catastrophe that occurs on the planet every 12,000 years, while every 24,000 years, it is more severe.
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How do we know about these catastrophes of the past?
They left behind a layer of destruction known as the Usselo Horizon. This layer, composed of soot and wood charcoal and ranging from 5 to 15 cm thick, has been found in the territories of ten countries across four continents.
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German geologists discovered that the layer formed during the massive eruption of the Laacher See volcano in Germany, and its ash was detected throughout Europe. Scientists attributed ——-
was found in North America and named the Clovis Horizon.
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Traces of large-scale fires of the same period were also found in Siberia. In catastrophic floods, intensification of winds, and a rise in sea levels.