The first image shows how some buildings in seismically active areas, like Southern California, have signs indicating they are constructed with unreinforced masonry, which means no reinforcing steel was installed in brick walls. Credit: Cory Doctorow, CC BY-SA 2.0. The second image is of a soft-story buildings. Such buildings are prone to collapse in earthquakes. Credit: Barmysot, CC BY-SA 3.0. The third image shows a precast concrete tilt-up building, which is a type of concrete building that is inexpensive to put up but performs poorly in earthquakes because of poor connections between the roof and walls. Credit: Duk, GNU Free license