Have you ever heard like if an enormous boat would be passing through your street?

I have been hearing that loud and long horn since I came here, it is the weirdest thing ever! But until today I haven’t actually looked what was that. And for my Google search I see that I am not the only one asking: “What the **** is that?!

It has a simple but surprising (at least for me) explanation:

It is the emergency siren of the city for civil defence, called colloquially “Hoarse Fredrik”.


It has a programmed test every first Monday of every third month at 15:00, so we can hear it 4 times per year in every city with a population of more than 1.000 habitants.

It is a system that started on the second World War and it is still in use for emergency warning to the population in case of approaching danger or even to indicate that the danger has passed. Examples of danger situations would be the city under attack, imminent war or climatic emergencies.

The system in Sweden:

  • Readiness alarm: 30 sec tones with 15 sec gaps. Used when imminent danger of war exists.
  • Air raid alarm: Short tone-bursts with a duration of 1 min. The country will or is being attacked from the sky.
  • Important message to the public, general alarm: 7 sec tones with 14 sec gaps. Go inside, close windows and doors, close ventilation and listen to radio channel P4.
  • All clear: Used for all above signals when danger is over. 30 sec single tone.

Basically in all the cases you would be asked to remain at home with everything closed and to watch the TV or listen to the radio announcements for the population.

Mystery solved!

Now my next inside question is, what would happen if the city is under attack on one of those Mondays?

If you still haven’t heard it or you want to be prepared, in Youtube I found a video of the alarm test in Gothenburg:

In Wikipedia and TheLocal you can find more information about this system.



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