Where do most earthquakes originate from (mantle or crust)? Why?

 Most earthquakes originate from the Earth's crust and uppermost part of the mantle. Earthquakes occur when there is a sudden release of energy stored in the rocks in the Earth's crust and uppermost part of the mantle. This energy is released in the form of seismic waves, which can cause the ground to shake and cause damage to buildings and other structures.

The majority of earthquakes occur along the boundaries of tectonic plates, where the Earth's crust is being deformed by the movement of these plates. These plate boundaries are known as the "Ring of Fire" around the Pacific Ocean, and are characterized by a large number of active volcanoes and frequent earthquakes. Earthquakes can also occur in the interior of tectonic plates, such as in the Midwest of the United States, and these are caused by the movement of the plates due to the convection of the material in the upper mantle.

The majority of earthquakes happen in the crust because that is where the tectonic plates meet and grind against each other, creating a lot of friction. The uppermost part of the mantle is also involved in the process because it is the layer that is in contact with the crust and it allows the movement of the tectonic plates, but the majority of the energy is released in the crust.

Deep earthquakes, those that occur at depths greater than 70 km, are less common and are caused by the movement of material in the lowermost part of the mantle, but most of them happen in subduction zones, where one tectonic plate is diving under another, and the majority of the energy is still released in the crust.