earthquake locations commonly occur in patterns called Benioff zones that dip into the Earth, indicating the presence of a subducting slab. Dip angles of these slabs average about 45°, with some shallower and others nearly vertical.

Wadati–Benioff zone. A Wadati–Benioff zone is a deep active seismic area in a subduction zone. Differential motion along the zone produces deep-seated earthquakes, the foci of which may be as deep as about 670 kilometres.

The most significant subduction zone, the Manila Trench subduction zone, is a 1,000 km-long zone between Taiwan and Mindoro Island in the Philippines. It is characterized by an east-dipping Wadati-Benioff zone that extends to ~200 km depth (Hamburger et al., 1983).

Subduction zones are plate tectonic boundaries where two plates converge, and one plate is thrust beneath the other. This process results in geohazards, such as earthquakes and volcanoes. This zone ‘locks’ between earthquakes, such that stress builds up. It is then released catastrophically in one or more earthquakes.

Eventually stresses exceed the fault’s strength and it breaks free, releasing the stored energy as seismic (shaking) waves in an earthquake. The massive size of these faults produce the largest earthquakes on Earth.

A megathrust earthquake is a very large earthquake that occurs in a subduction zone, a region where one of the earth’s tectonic plates is thrust under another. Eventually the build-up of strain exceeds the friction between the two plates and a huge megathrust earthquake occurs.

The world’s greatest earthquake belt, the circum-Pacific seismic belt, is found along the rim of the Pacific Ocean, where about 81 percent of our planet’s largest earthquakes occur. It has earned the nickname “Ring of Fire”.

Transform boundaries are areas where the Earth’s plates move past each other, rubbing along the edges. As the plates slide across from each other, they neither create land nor destroy it. Because of this, they are sometimes referred to as conservative boundaries or margins.

The heat from radioactive processes within the planet’s interior causes the plates to move, sometimes toward and sometimes away from each other. This movement is called plate motion, or tectonic shift.

Mars, however, doesn’t have plate tectonics. After its formation, the planet was a searing mass of molten rock that eventually cooled to form a static crust around a rocky mantle, yet it’s unclear how hot the planet’s insides are today.

Olympus Mons is still a relatively young volcano. Although it has taken billions of years to form, some regions of the mountain may be only a few million years old, relatively young in the lifetime of the solar system. As such, Olympus Mons may still be an active volcano with the potential to erupt.