Switzerland’s sirens serve as a public warning system in case of national emergency.
The system was established during World War Two to warn of bomb threats but is now used to warn of events such as major flooding, an imminent threat or the breakdown of a nuclear power plant.
There are two types of warning sirens. The first, indicating general disaster, is a continuous oscillating siren lasting around a minute. The second, used to warn people who live downstream of dams of impending water-related catastrophe, is a series of 12 bursts of 20 seconds each at ten-second intervals.
The first warning sirens will be tested at 1.30pm, with tests continuing as necessary until 2pm. The water-emergency related alarms will be tested from 2.15pm until 4pm.
During the testing on February 7th this year a technical problem was discovered in the software used by the centralised system that regulates the alarms, meaning the testing was only a “partial success”, the Federal Office for the Protection of the Population (FPOP) said at the time.
The office said the sirens would still have functioned in the event of a real emergency.