It was Seattle's turn to play shutout tonight. Blanked twice in a row by the Baltimore Orioles, the Mariners returned the favor, 6-0, on a four-hitter by right-hander Mike Moore.

Gorman Thomas aroused the visitors from their offensive doldrums with a pair of two-run homers. It was the fifth time this season he had hit two or more homers in a game. His shot off Mike Flanagan in the first ended a 20-inning scoreless string for Seattle.

The last time Moore pitched here, in May, he departed in the second inning with a strained thigh muscle and spent 21 days on the disabled list. But tonight he walked only two and struck out eight to improve his record to 12-8.

Moore gave up three hits in the first two innings, then was unhittable until Mike Young's two-run double in the ninth. It was Moore's eighth complete game, half the Mariners' total.

"My shoulder stiffened in the eighth, but since I had a shutout I wanted to stay in there," said Moore, a huge ice pack attached to his right shoulder. "My last start Sunday against New York, I had nothing and my arm was dead, but I bounced back good tonight.

"I had better concentration and I found my good hard slider again. I was throwing it for strikes ahead or behind on the count. Since the slider was good, I didn't want to waste it, so I threw a lot of them."

In an oddity, of the 11 Orioles Moore retired on grounders, none hit the ball to the left side of the infield. First baseman Alvin Davis took care of six, second baseman Jack Perconte three and Moore two.

The defeat ended an eight-game Memorial Stadium winning streak for the Orioles and dropped them back into fourth-place in the American League East after a 24-hour sojourn in third.

Flanagan (2-4) again was hurt by the home run ball, as Thomas' first-inning homer was the seventh he has allowed in 24 1/3 innings. Flanagan departed with one out in the second, after an RBI single by Perconte brought Seattle's lead to 3-0.

Sammy Stewart finished up and yielded Thomas' second homer in the fifth, as well as a ninth-inning unearned run when he balked with two out and Thomas on third.

Thomas entered the game with a two-for-16 mark against the Orioles. After striking out three times against Mike Boddicker Thursday, he watched Storm Davis' shutout Friday from the bench. But Thomas arrived early for extra batting today and it paid off.

"D.J. (batting coach Deron Johnson) and I went to the tunnel and tried to change things a bit," Thomas said. "I wasn't comfortable, so I moved my hands a little higher on the bat. I took about 100 swings. I felt good and I carried it into the game.

"A big key to our club is to get ahead early. We tend to play better when we're in front . . . "

Thomas underwent surgery 15 months ago for a torn rotator cuff and still cannot throw a ball properly. But he was out there throwing Friday, knowing he was not scheduled to play, and he, like Moore, had a big ice pack on his right shoulder after tonight's game.

The Orioles recalled pitcher Bill Swaggerty from their Rochester farm club today and purchased the contracts of five other players from the roster of the International League team.

Among those scheduled to report to the Orioles Tuesday are veteran infielder Lenn Sakata, pitcher Brad Havens, infielders Kelly Paris and Tom O'Malley and outfielder Leo Hernandez.

Former Orioles pitcher Jim Palmer will be honored Sunday in a 1 p.m. ceremony preceding the game against the Mariners.

Palmer had a 268-152 record between 1965 and 1984. His No. 22 will be the fourth uniform retired by the club, following those of Earl Weaver (4), Brooks Robinson (5) and Frank Robinson (20).