A 4.6-magnitude earthquake struck west of Los Angeles on Friday, with the potential for the reported magnitude to be revised as more data is collected. Aftershocks, which are smaller earthquakes that follow a larger one, could occur in the same general area, causing additional damage. These aftershocks can occur days, weeks, or even years after the initial earthquake and may be of equal or larger magnitude. The United States Geological Survey is monitoring the situation and updating their shake-severity map as more information becomes available. Shake categories are based on the Modified Mercalli Intensity scale, and aftershock data is included in maps and charts for earthquakes within 100 miles and seven days of the initial quake. As of Friday, Feb. 9 at 4:52 p.m. Eastern, and Saturday, Feb. 10 at 8:32 p.m. Eastern, the data is as follows.