There is a correlation between the magitude and the intensity of the earthquake. Even though this correlation is there, it may be difficult to link one to the other: This correlation depends on several factors, such as the depth of the earthquake, terrain, population density, and damage. For example, on May 19, 2011, an earthquake of magnitude 0.7 in Central California, United States 4 km deep was classified as of intensity III by the United States Geological Survey (USGS) over away from the epicenter (and II intensity almost from the epicenter), while a 4.5 magnitude quake in Salta, Argentina 164 km deep was of intensity I.