What was that bang?

A loud bang is rarely explained by one person alone. You usually only know it was loud, short, and came from outside. A picture forms only when several people independently describe when and where they heard it. That is what this site is for.

Reports from the same city within twenty minutes are grouped into one event. Separate impressions become a number: “eleven people heard this” says more than eleven isolated posts. If a bang hits several cities at once, it becomes a major event — a strong sign of a sonic boom or a larger blast.

Common causes

• Sonic boom: typically a hard double bang heard across tens of kilometres at once. Windows rattle with nothing visible nearby.
• Fireworks: usually several bangs in a row, in the evening, with light in the sky and a limited range.
• Explosion or blast: a single very hard bang with no light, often in daylight and with no obvious reason.
• Military or artillery: dull, often in series and over hours, heard far away. Often announced exercises or ranges.
• Building site or demolition: recurring, during working hours, often in the same areas.
• Lightning strike: a single very hard bang in a storm, often with a visible flash nearby. Sharper and closer than rolling thunder.
• Thunder: rolling rather than a sharp crack, with a storm and usually visible lightning.

What this data is not

Every entry is an unconfirmed observation, not a measurement and not an official record. They show that many people heard something at about the same time in about the same place. Nothing more. If there is smoke, fire, a gas smell or injuries, call emergency services first: 911.

Stats and history