The earthquake, barely recognizable at AT&T Park, was measured as a 3.5 on the Richter scale and centered in Piedmont, Calif., a suburb of Oakland on the east side of the bay.
The loss snapped Cincinnati's six-game winning streak.
The Giants jumped on Reds starter Sal Romano (2-4) for three runs shortly after the quake, with Evan Longoria opening the scoring with an RBI single and Brandon Crawford making it 3-0 with a two-run double.
Belt singled to open a two-run third, smacked a two-RBI double in a three-run sixth and capped the Giants' big offensive night with his seventh home run of the season, a solo shot, in the eighth inning.
Giants starter Chris Stratton (4-3), who worked five innings, benefitted from the offensive assault. He allowed four runs and nine hits, including home runs by Tucker Barnhart, his third, and Scott Schebler, his fifth.
Stratton walked two and struck out one.
The Giants roughed up four Reds pitchers for a total of eight extra-base hits, including seven doubles. Crawford and Andrew McCutchen had two doubles apiece.
McCutchen's first double, which came in the first inning, was his 1,500th career hit. He became the 43rd player ever to reach the milestone in a Giants uniform, the most of any team.
The double also extended his hitting streak to 13 games and his string of consecutive games reaching base to 24.
Crawford, McCutchen, Longoria and Buster Posey had two hits apiece for the Giants, who out-hit the Reds 14-13.
The Giants scored 10 or more runs for the third time this season. They are seeking to record their fourth straight series win at home in this three-game set.
Barnhart drove in three runs, two with a second-inning single. He finished with two hits, while Schebler had three for the Reds, who were coming off a four-game sweep in Los Angeles against the Dodgers to open a seven-game trip.
Adam Duvall, who capped the scoring with a three-run home run in the ninth inning, and Jesse Winker added two hits apiece for the Reds.
The Reds had allowed a total of just 12 runs during their six-game winning streak.
Romano was pulled after allowing six runs and eight hits in 2 1/3 innings. He walked two and struck out two.
--Field Level Media
Cincinnati | San Francisco | |
Sal Romano | Player | Chris Stratton |
Loss | W/L | Win |
2.1 | IP | 5.0 |
2 | Strikeouts | 1 |
8 | Hits | 9 |
23.14 | ERA | 7.20 |
Cincinnati | San Francisco | |
Scott Schebler | Player | Brandon Belt |
3 | Hits | 3 |
1 | RBI | 3 |
1 | HR | 1 |
7 | TB | 7 |
.750 | Avg | .600 |
Team | Hits | HR | TB | Avg | LOB | K | RBI | BB | SB | Errors |
Cincinnati | 13 | 3 | 25 | .351 | 15 | 5 | 7 | 2 | 0 | 2 |
San Francisco | 14 | 1 | 24 | .359 | 23 | 6 | 10 | 4 | 2 | 1 |