The third and fourth quakes, a 1.8 and a 1.7-magnitude, respectively, were weaker than the previous two, which came in at 2.7 and 2.0.
The third temblor happened at about 10:40 p.m. on Tuesday and originated from an epicenter about 3.7 miles from southwest of Newton.
The fourth happened at about 1:12 a.m. on Wednesday about 3.7 miles east of Mountain View.
No damage was reported from either earthquake.
Since at least 1776, people living inland in North and South Carolina, and in adjacent parts of Georgia and Tennessee, have felt small earthquakes and suffered damage from infrequent larger ones, according to USGS. The largest earthquake in the area (magnitude 5.1) happened in 1916. Moderately damaging earthquakes strike the inland Carolinas every few decades, and smaller earthquakes are felt about once each year or two.