The 1556 Shaanxi earthquake (formerly romanized Shensi), known in Chinese colloquially by its regnal year as "" (Jijng Ddzhn) or professionally by its epicenter as "" (Huxin Dzhn), occurred in the early morning of 23 January 1556 in Huaxian, Shaanxi during the Ming dynasty.

Most of the residents there lived in yaodongsartificial caves in loess cliffswhich collapsed and buried alive those sleeping inside. Modern estimates put the direct deaths from the earthquake at over 100,000, while over 700,000 migrated away or died from famine and plagues, which summed up to a total loss of 830,000 people in Imperial records. It is one of the most fatal earthquakes in China, in turn making it one of the top disasters in China by death toll.

An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in size from those that are so weak that they cannot be felt to those violent enough to propel objects and people into the air, and wreak destruction across entire cities. The seismicity, or seismic activity, of an area is the frequency, type, and size of earthquakes experienced over a particular time period. The word tremor is also used for non-earthquake seismic rumbling.

At the Earth's surface, earthquakes manifest themselves by shaking and displacing or disrupting the ground. When the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause a tsunami. Earthquakes can also trigger landslides and, occasionally, volcanic activity.

In its most general sense, the word earthquake is used to describe any seismic event—whether natural or caused by humans—that generates seismic waves. 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 earthquake's point of initial rupture is called its hypocenter or focus. The epicenter is the point at ground level directly above the hypocenter.