we are here to talk about rockslide, rockfalls, and related issues. what is the difference between a geologist and a geotechnical engineer? >> and engineering geologist deals with identifying site characteristics, mapping, the ground's surface, collecting all of this data. the engineer can come up with medications and designs. >> the structural engineer might be working on a building if there is a building involved. what is your role? >> i am interested in the physical properties of the earth and how the earth will behave: subject to different load changes. when you are building a building, you are applying a load and you are wondering if the earth will be able to supply that load. we work closely together and we come up with practical engineering solutions. >> this is when someone wants to build something. also, we have a rock piece of land. we have to have a resolution. >> in the u.s., about 2/3 of the population lives in areas that are prone to landslides. about $2 billion of damage occurs annually from landslides. unfortunately, 20-25 million peop