Earthquakes change the Earth by affecting and destroying landscapes, structures and environments, which threatens the inhabitants of an area and the area's entire geology. An earthquake in one place can cause a series of events that resonate out and change entire environments that are nowhere near the site of the actual earthquake.
Earthquakes are caused by either volcanic activity or shifting of massive tectonic plates underneath the surface of the earth. The plates have a ton of pressure and are pressing against each other, and when the plates suddenly shift it causes the entire ground to move, shake or break apart.
There are plenty of earthquakes that occur that are so mild that no damage is done, but some earthquakes make the ground shake so violently that it destroys entire landscapes and environments. Most human deaths from earthquakes are a result of earthquakes knocking down buildings or manmade structures. However, earthquakes can also cause landslides and tsunamis, which destroy whole villages, change geology and ruin natural habitats of many living creatures. For instance, when an earthquake happens in the middle of the ocean, it can create waves that are so large that they destroy coastlines, cities, and forests hundreds of miles away.
Earthquakes have helped to shape the Earth's landscapes, but they also continue to alter those landscapes. Earthquakes are dangerous to human, plant and animal life, and when large earthquakes occur, they have the power to drastically change the surface of the Earth.