Glossary
The terms on your USCIS receipt notice and the processing times tool, explained in two sentences.
Magnitude
A number describing the energy an earthquake released at its source, on a logarithmic scale.
Intensity
How strongly shaking is felt and how much damage occurs at a specific location.
Epicenter
The point on the surface directly above where an earthquake's rupture began.
Hypocenter Depth
How far below the surface an earthquake's rupture began, which shapes how hard the surface shakes.
Aftershock
A smaller quake that follows a mainshock as nearby faults adjust to the new stress.
Subduction Zone
Where one tectonic plate slides beneath another, producing the planet's largest earthquakes.
Fault
A fracture in the Earth's crust where blocks of rock move past each other, releasing quakes.
Moment Magnitude
The modern magnitude scale (Mw) based on the physical size of the fault rupture.
Mainshock
The largest quake in a sequence; smaller ones before it are foreshocks, after it aftershocks.