Earth Science

Astronomy is a natural science that deals with the study of celestial objects (such as stars, planets, comets, nebulae, star clusters and galaxies) and phenomena that originate outside the Earth's atmosphere (such as the cosmic background radiation). It is concerned with the evolution, physics, chemistry, meteorology, and motion of celestial objects, as well as the formation and development of the universe.

Northridge Earthquake

The Northridge earthquake occurred at 4:30 a.m. local time on January 17, 1994. Northridge is located about 30 km northwest of Los Angeles. This earthquake had a 6.9 moment magnitude. The hypocentral depth was 19 km. The duration was about 10 seconds to 20 seconds. The earthquake occurred along a "blind" thrust fault, close to the San Andreas fault. Note that a blind fault is a fault which does not extend to the surface. In other words, it is buried.

The Northridge earthquake was the worst earthquake in the Los Angeles basin since the San Fernando earthquake in 1971, which had a 6.7 magnitude.