The earthquake that struck Coalinga, California in 1983 caused an estimated $10 million in property damage and injured 94 people. Damage was most severe in Coalinga, __36__ the 8-block downtown commercial district was almost completely destroyed. It took residents by surprise. That’s because scientists cannot yet predict the exact spot and time an earthquake will occur. They do know, __37__ , that quakes occur along faults—cracks in the earth’s rocky crust. Here, movement of the crust causes built-up energy to be suddenly released. This release of energy is felt as an earthquake. To try to predict __38__ a quake will occur, scientists use a variety of sensitive instruments—underground, on the surface, and in space. These instruments measure changes that might signal a coming quake. __39__ , in a recently designed instrument, light from a laser flashes across a fault in California. A mirror will reflect the light back to the laser. If the land shifts, the time it takes the light to make a round-trip changes. Scientists study past earthquakes for patterns of activity that can __40__ warning signs. Their observations, they believe, are providing keys to more accurate earthquake predictions.