HONOLULU (AP) _ A six-block area of Waikiki Beach is sinking - splitting sidewalks, tilting small buildings and making streets uneven - but a building contractor has taken responsibility.

In order to excavate a block-sized area in the heart of the tourist mecca to a depth of 30 feet as part of a $50 million commercial project, Pacific Construction Co. has been pumping up to 7,000 gallons of groundwater out of the hole every minute since May.

Officials of Pacific Construction accepted responsibility and have had crews scrambling around to fill and patch the newest pavement cracks or gaps between sidewalks or sagging walls and buildings as soon as they are reported.

Engineers and consultants who planned the project and city officials who approved the plans assumed there would be some soil settlement, said the city's chief building inspector, Sadao Kaneshiro.

The water table in the area is just 6 feet below the surface.

''Whenever you take out groundwater, the surrounding areas will be affected,'' Kaneshiro said. ''They knew that, but it's a matter of degree. They didn't know how much.''

In some places, the subsidence has been as much as 4 inches.

Pumping - and, officials hope, the sinking - will stop when construction reaches the fourth-floor level in about six weeks, said Trudie China, Pacific Construction's marketing manager.

Managers of neighboring buildings are pleased with Pacific Construction's response, but don't like the nuisance and think the contractors and city should have anticipated the problem.

''After all, Waikiki is built on a swamp, and these guys are draining the swamp,'' said John Van Apell, building manager of the nearby Royal Kuhio condominium.

Steve Winter, general manager of the Waikiki Joy Hotel, across the street from the hole, said he is trying to take the problem in stride and ''can't give enough credit to Pacific Construction for trying to repair the damage.''

Kimberly Line, administrator of the 13-story Laniolu Retirement Home and Care Center, said ''it's not just the actual damage, it's the mental anguish the residents go through. They ask me, 'Are we still safe? Is the building going to fall down?'''

Willella Reub, a resident of Laniolu, said it's a question of comfort. Her wheelchair ''rides hard'' over the bumps caused by the subsidence, she said.