WHISTLE / earthquake rescue goods

Many people get a serious damage from earthquakes which break out worldwidely every year. Especially, survivals under the building debris are hard to be saved because of their vague location. Heavy equipments can be mobilized to save them but there is a possibility the people get harm from those equipments.
As a result, rescue team usually do their job without large equipments, and without knowing the location of the victims. To save survivors more quickly, another way to acquire the position of them more quickly is required.