b'EARTHQUAKESMost of the worlds earthquakes result from thein rigid crust breaks and faults as seen in Figure9movement of the large tectonic plates that compose Fault Lines in Idaho. These faults can produce Earths outer crust. These earthquakes occur when twolarge earthquakes. The area most prone to quakes or more crustal plates suddenly slip past one another.is the Intermountain Seismic Belt, which runs from The surface where they slip is called the fault or faultthe northwest corner of Montana, along the Idaho-plane. The location below the earths surface whereWyoming border, through Utah, and into southern the earthquake starts is called the hypocenter, and theNevada (see Figure 10). While many earthquakes location directly above it on the surface of the earth isoccur along faults, many small to moderate called the epicenter.4 These kinds of earthquakes areearthquakes do not. Furthermore, many of the faults common along the Pacic Coast. While the largest ofin Idaho remain unmapped and most quakes are these may be felt in Idaho, most earthquakes in thenot associated with known faults. This, along with state originate far from tectonic plate boundaries. Thea low density of seismic monitoring stations makes Basin and Range Province of southern and centralearthquake location precision dicult.Idaho has undergone tremendous stretching in a northeast-southwest direction, resulting in parallel,Additionally, the Yellowstone Hotspot interacts with linear mountains and valleys. Basin and Rangethe Basin and Range to create a more complicated stretching is continuing today and earthquakes frompattern of earthquakes and mountain building called these crustal movements can cause severe groundthe Yellowstone Tectonic Parabola. The Yellowstone shaking in Idaho. Earthquakes may also arise fromTectonic Parabola is a region of earthquakes, active magmatic activity. The Yellowstone Hotspot is afaulting, and topographic uplift surrounding the conduit carrying molten rock (magma) from deepeastern Snake River Plain. Much of the earthquake within the earth to the crust. Pressure builds withinactivity in eastern and central Idaho is thought to be the hotspot and leads to earthquakes. The Yellowstonerelated to interactions between these two tectonic Hotspot doesnt release any surface magma, at whichforces. While all of Idaho is subject to at least a point it becomes lava, but it is still very seismicallymoderate threat from earthquakes, the mountainous active, with dozens of small earthquakes beingregions of eastern and central Idaho, north and recorded in the Yellowstone region each month. south of the Snake River Plain are most prone to large, damaging earthquakes, though the Snake Although Idaho does not lie near a fault boundary,River Plain itself has very little earthquake activity.2the stretching that occurs throughout the state results Natural Hazards 109'