Feudalism was a combination of legal and military customs in medieval Europe that flourished between the 9th and 15th centuries. Broadly defined, it was a way of structuring society around relationships derived from the holding of land in exchange for service or labour. Although derived from the Latin word feodum or feudum, then in use, the term feudalism and the system it describes were not conceived of as a formal political system by the people living in the Middle Ages. In its classic definit
Causes of Earthquakes. Most earthquakes are causally related to compressional or tensional stresses built up at the margins of the huge moving lithospheric plates that make up the earth's surface (see lithosphere).
Earthquakes are caused mostly by rupture of geological faults, but also by other events such as volcanic activity, landslides, mine blasts, and nuclear tests. An earthquakeâs point of initial rupture is called its focus or hypocenter. The epicenter is the point at ground level directly above the hypocenter.arthquakes often occur in volcanic regions and are caused there, both by tectonic faults and the movement of magma in volcanoes. Such earthquakes can serve as an early warning of volcanic eruptions, as during the Mount St. Helens eruption of 1980.