Okay kiddo, do you know what an earthquake is? It is when the ground shakes really hard because of the movement of rocks deep inside the earth.
Now, there are some people who are really interested in studying earthquakes because they want to make sure that buildings and structures are strong enough to withstand the shaking. These people are called earthquake engineers.
The earthquake engineering research institute (EERI) is a group of these earthquake engineers who work together to study earthquakes and their effects on buildings. They do a lot of research to figure out how to make buildings and structures stronger so they don't collapse during an earthquake.
They also teach other people, like architects and builders, how to make buildings that can stand up to earthquakes. This way, people can be safer when there is an earthquake.
So, basically, the EERI is a bunch of really smart people who want to make sure that buildings don't fall down during earthquakes by figuring out how to make them stronger.