An earthquake rattled much of the Northeast on Friday morning, with shaking felt across the New York City metropolitan area and in communities from Baltimore and Philadelphia up through New England.

What does “moment magnitude” mean, and how do scientists determine the strength of a rupture in the earth? By Henry Fountain Henry Fountain spent a quarter century covering science for The Times. He ...

Earthquake strength is registered on the moment magnitude scale, which measures how much energy was released when the rocks along a fault moved during the quake. By Henry Fountain Earthquake strength ...