The Western Conference leaders struck four times in the opening 42 minutes as the Sounders claimed a relatively comfortable win at the StubHub Center.
Obafemi Martins and Andy Rose both netted braces for Seattle, who are five points clear atop the table.
Marco Delgado and Ryan Finley pulled goals back early in the second half for the conference's bottom team.
Martins started what proved to be a devastating first half for the Sounders.
A Brad Evans corner was headed goal ward by Chad Marshall and Martins was on hand to scramble in from close range.
Just five minutes later and it was 2-0 in even easier fashion.
Clint Dempsey's pass saw Lamar Neagle through and he squared for Martins to tap into an open goal.
Rose scored in the 38th and 42nd minutes as the Sounders rolled out to a 4-0 lead in California.
Delgado's looping header at the back post saw Chivas USA pull a goal back in the 51st minute.
Finley was brought down by Zach Scott leading to a penalty for Chivas USA and he converted on the hour-mark.
But that would be the last bit of joy they would have as their winless run was extended to eight matches.
Lee Nguyen's second-half brace saw New England upset Sporting Kansas City 3-1.
Greg Vanney's first game in charge of Toronto resulted in a loss as his team were beaten 1-0 by the Philadelphia Union.
