Earthquakes are linked to the natural movement of the Earth's crust. Volcanoes and tectonic plate activity can shift the placement of areas in the Earth's crust, resulting in an earthquake. The Earth is made up of various tectonic plates that are pressing against one another in different places. When one of the plates shifts due to the stress, that shifting causes an earthquake. The majority of the earthquakes that occur are attributed to the shifting of tectonic plates. Volcanic earthquakes occur less frequently. These types of earthquakes occur when a volcano erupts, often in an explosive manner. These volcanoes can be above or below sea level.
Earthquakes are rated depending on their strength on the Richter magnitude scale. The scale is a base-10 logarithmic scale that starts at 0 and rises to 10. For example, an earthquake that is rated as a 5.0 on the Richter scale is 10 times stronger than a 4.0 earthquake. This scale is used to determine how strong an earthquake was. According to the Richter scale, earthquakes should have a ranking of 4.0 before they cause any form of significant damage.
Earthquake damage greatly depends on the strength of the quake and the area that is hit during the occurrence. Populated areas such as large cities will face a higher level of damage than that of an unpopulated area. Earthquakes with a strong magnitude will cause additional types of disasters such as avalanches and landslides. The tsunami that hit Japan in 2011 was the result of an earthquake that occurred near the country. Earthquakes are strong enough to topple buildings and cause other structures to give way under the stress. Today, construction projects in areas prone to earthquakes are now built to withstand earthquakes of varying degrees.
Throughout history earthquakes have caused many disasters. In 2004 an earthquake with a magnitude of 9.1 in the Indian Ocean caused a tsunami that struck Thailand and caused the death of more than 200,00 people. In 2007 an earthquake in Chile caused landslides that affected numerous parts of the country. This earthquake was rated a 6.2 on the Richter scale. The state of California lies upon various fault lines that are active throughout the year. While the state hasn't been hit by a major earthquake recently, the earthquake of 1906 ranks among the strongest to ever hit the country.