Trapped or buried under debris: making yourself known

Sound is a vibration. In air it quickly loses strength, especially when there are many obstacles in between, such as rubble, furniture and pieces of wall. In solid materials like metal, concrete or wood, sound is passed on well. A pipe or steel beam can therefore carry a knock a long way through a building, to places where helpers are listening.

The rhythm matters. A single crack could come from shifting rubble. A steady, repeated pattern such as three knocks, pause, three knocks sounds clearly like a person. The same goes for whistles: three blasts at intervals are a widely used distress signal.

Rescue teams at incident sites often work with quiet periods. Machines are switched off, everyone is silent, and the helpers listen specifically for tapping and calls. If you keep tapping at intervals, you have a good chance of being heard during such a quiet period.

If your phone still works, that is the fastest route: call the emergency number or send a message to trusted contacts. Describe your location as precisely as possible: which building, which floor, which room, how many people are with you. A message sometimes gets through when a call fails because the network is overloaded.

Save your strength and air. Breathe calmly, move as little as possible and do not pull at debris without control, because the rubble can shift. Cover your mouth and nose with cloth, for example a sleeve or scarf, so that you breathe in less dust.

Do not tap non-stop, but at intervals. That way you last longer and can listen in the pauses for an answer. If you have a torch and gaps lead to the outside, you can switch it on in short bursts – a constant light drains the battery.

After earthquakes and collapses, gas pipes may be damaged. Gas can collect in voids, and even a small spark or flame can ignite it. So never use matches, lighters or candles for light. A torch or phone light are the safe light sources.

If there is fire or smoke reaching you, something else applies: call the emergency number as fast as possible and follow the dispatcher's instructions. The method described here is meant for situations in which you wait safely until help reaches you.

This entry does not explain how to free yourself or pull others out of debris. That is dangerous and a job for trained rescuers. With injuries: stay calm, call the emergency number and follow the dispatcher's instructions.

A small signal whistle is the most effective tool for this situation. It is loud, takes hardly any effort, needs no power and fits on a key ring or in an emergency bag. Official guidance for earthquake areas specifically recommends having a whistle within reach.

Anything hard works for tapping: a key, a stone, a piece of metal, a shoe with a hard sole. Ideally tap on metal, such as a heating or water pipe, because metal conducts sound particularly well. If there is no pipe, use a wall or a beam.

If you live in or travel to an earthquake area, you can keep a whistle and a small torch next to your bed. It costs little and is right at hand in an emergency.

Many people think they have to scream as loudly as possible to be found. Official preparedness guidance advises exactly the opposite: shout only when helpers are close, and until then tap or whistle. Shouting uses a lot of energy, dries out your throat and makes you breathe in dust.

Waiting can take a long time, and that is hard. It helps to give yourself a rhythm: tap, listen, rest, tap again. When you hear voices, machines or dogs, that is the moment to get louder and shout.

In the noise of a large incident site, tapping can also be missed. That is why patience matters: do not give up, but carry on at intervals – especially when it suddenly goes quiet.