 After an earthquake, how can people know a building is still safe to live in and will not collapse? In Mexico, a nuclear technology will be used to check the safety of buildings damaged by a strong quake last September. After a earthquake, we need to evaluate all kinds of infrastructures. In special cases, we need very special techniques such as nuclear techniques. The 7.1 magnitude earthquake destroyed hundreds of buildings in the capital, Mexico City. Many damaged structures still stand. The IAEA briefed Mexican experts about using non-destructive testing techniques to examine the condition of these buildings. It is essential to have people at least prepared to quickly decide when to evacuate or not to build a building. What we want is a systematized, fast and precise way to evaluate civil buildings that can provide a risk to the population. Non-destructive testing is a group of inspection techniques used to assess the properties of materials, components and structures. Some methods rely on radiation to peer deep inside. Instructions allow us to create a very advanced idea of how the structure is and what the structure is made of. Countries can use these techniques to quickly and efficiently test structures with portable equipment without causing any damage to the object. This is the first time we would use it to evaluate civil type structures in urban areas. The IAEA provided similar assistance after devastating earthquakes in Ecuador in 2016 and Nepal in 2015 and will continue to support its member states in responding to natural disasters.