Earthquakes are caused by a sudden slip on a fault. The tectonic plates are always slowly moving, but they get stuck at their edges due to friction. When the stress on the edge overcomes the friction, there is an earthquake that releases energy in waves that travel through the earth's crust and cause the shaking that we feel. In addition, it can be caused by the sudden release of energy within some limited region of the rocks of the Earth. The energy can be released by elastic strain, gravity, chemical reactions, or even the motion of massive bodies, Earthquakes associated with this type of energy release are called tectonic earthquakes.

Earthquakes mostly occur along geologic fault lines, narrow zones where rock masses move in relation to one another. The major fault lines of the world are located at the fringes of the huge tectonic plates that make up Earth’s crust. In addition, most of the world’s earthquakes occur within the Pacific Ring of Fire (also known as Circum-Pacific Belt), a long horseshoe-shaped belt of earthquake epicentres, volcanoes, and tectonic plate boundaries fringing the Pacific Basin.

There are four principal types of elastic waves: primary and secondary, travel within Earth, whereas the other two, Rayleigh and Love waves, or known as surface waves, travel along its surface. In addition, seismic waves can be produced artificially by explosions.

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Magnitude is a measure of the amplitude (height) of the seismic waves an earthquake’s source produces as recorded by seismographs. Seismologist Charles F. Richter created an earthquake magnitude scale using the logarithm of the largest seismic wave’s amplitude to base 10. Richter’s scale was originally for measuring the magnitude of earthquakes from magnitudes 3 to 7, limiting its usefulness. Today the moment of magnitude scale, a closer measurement of an earthquake’s total energy release is preferred.

DID YOU KNOW? The world's largest earthquake with an instrumentally documented magnitude occurred on May 22, 1960 near Valdivia, in southern Chile. It was assigned a magnitude of 9.5 by the United States Geological Survey. It is referred to as the "Great Chilean Earthquake" and the "1960 Valdivia Earthquake."

We cannot prevent natural earthquakes from occurring but we can significantly mitigate their effects by identifying hazards, building safer structures, and providing education on earthquake safety and preparing for natural earthquakes we can also reduce the risk from human induced earthquakes.

Substantial seismological work was done to understand the characteristics of the soil motions reported in earthquakes. Such awareness is important in future earthquakes in order to develop earthquake-resistant structures. Although seismic effects such as ground slides, tsunami and fires cause death and devastation, most losses—both of life and property—related to the collapse of human-made structures in the violent earthquake. In engineering terms, designing and constructing structures that can withstand strong ground movements is the most efficient way of minimizing earthquake damage.

Make an Emergency Plan: Create a family emergency communications plan that has an out-of-state contact. Plan where to meet if you get separated. Make a supply kit that includes enough food and water for several days, a flashlight and a whistle. Don’t forget to include your pet in your emergency plan. Remember that some evacuation shelters do not accept pets. Click here to know how to make an emergency plan

Build an emergency kit with the supplies you will need if you have to quickly evacuate your home. Gather supplies, including non-perishable foods, cleaning supplies, and water for several days, in case you must leave immediately. It is recommended that there is at least 3 days’ worth of supplies on hand, including one gallon per day for each person and pet. Click here to know how to make an emergency kit