The earthquake in Maryland was reported by the U.S. Geological Survey (USGS) to have hit at 5:04 AM EDT, approximately 30 km (19 mi) NE of Washington/Dulles, DC. That said, people are reporting it as the DC earthquake as well.
The earthquake was really an earthquake in Maryland, however. The USGS reported it was 2 km ( 1 mi) SE of Germantown, MD.
The earthquake in Marylaned was the largest in the area since 1974. It was also the first earthquake registering above 3.0 on the Richter scale there in that time period.
To compare, while the earthquake in Maryland measured 3.6, the great Haitian earthquake from earlier this year registered 7.0 on the Richter scale. Meanwhile, the Chilean earthquake earlier this year was a magnitude 8.8.
The Richter scale is base-10 logarithmic. What that means is that each rise of 1.0 on the scale means that the earthquake registered 10x the shaking amplitude of the lower reading. One can then see that a rise of two points would then mean 100x the shaking amplitude. Thus, the earthquake in Maryland shook up residents there, but was much lower in power than a devastating earthquake would be.