Gaston Brugman also scored a goal for the Galaxy (13-12-7, 46 points), who are tied with the Portland Timbers for the fifth-most points in the Western Conference with two matches remaining. The top seven teams make the playoffs.
Cristian Espinoza and Nathan scored for the Earthquakes (7-15-10, 31 points), who are in last place in the 14-team West. San Jose is winless in its last four matches (0-3-1) while being outscored 12-4.
The Earthquakes held a 13-11 edge in shots, but the Galaxy put four on target to San Jose's three.
Chicharito scored his first goal of the game in the 12th minute when he sent a close-range left-footed shot past Marcinkowski.
The Galaxy made it 2-0 in the 42nd minute when Brugman unleashed a hard right-footed shot from outside the box. The ball hit the underside of the crossbar and went into the net for his third goal of the season.
Los Angeles had a 5-1 edge in shots in the first half.
Chicharito was back at it again in the 69th minute when he engineered a give-and-go with Efrain Alvarez and sent a right-footed grounder into the left corner of the net. It was Chicharito's 17th goal of the season, and the brace was his fourth of the campaign.
A short time later, Espinoza had a breakaway attempt, but Bond knocked him down to the ground and a penalty kick was awarded. Espinoza stood at the spot in the 74th minute and easily booted a right-footed shot into the right corner of the net for his seventh goal of the season.
Nathan sent a header over the net off a corner kick in the 86th minute.
But in the fifth minute of second-half stoppage time, Nathan sent a header on net that glanced off a Galaxy defender and past Bond just before play was signaled over by the referee.