We seem particularly prone to these in the US. The Germans tend to this as well. "Welle." Is that the word in German?
A few recent cases come to mind:
-The terrible fear of the end of civilized life that preceded the year 2,000.
– The terrible fear of "the terrorists" that overwhelmed the country in the months after 9/11. People hid out at home for weeks, refusing to go to work in places like the World Bank in Washington, DC. People stared hostilely at each other on public transportation if there was anything unusual about a person's appearance. "If you see something, say something." Like a beard, perhaps
– The wave of insane trials in the 90s of the staff and owners of child day care centers for child molestation, satanic ritual, etc. on the basis of elicited testimony of three and four year olds. A sample test question in court was "Is red heavier than yellow?" Actual answer from a child witness – "Yes." On the basis of such testimony many were sent to prison for long terms. The public was quite happy with that. No, the public was quite enthusiastic about it.
Now we have an MSM and social media induced madness over the death of St. George of Minnesota. The craziness has led to successful mob demands for the destruction of historic monuments, toleration by business leaders of looting, and such whackiness as the proposed abolition of police forces and a reliance instead on the goodness of mankind. The public, to include TeeVee executives have now meekly surrendered to the mob and are actually doing things like cancelling profitable programs that are about the police. What are they going to do in the UK? Half their programming seems to be about policing. What will Her Majesty do if deprived of her favorite show, "Midsomer Murders?"