There's been no public announcement that Amazon.com is headed to South Lake Union, but the online retailer's landlord on Beacon Hill appears to be preparing for its departure anyway.

Wright Runstad President Greg Johnson said Monday he's showing the 190,000 square feet of space that Amazon occupies at Pacific Medical Center to possible tenants that are looking to move or expand in mid-2010.

That's when Amazon's lease at the Seattle landmark expires — and when Paul Allen's development company, Vulcan Real Estate, plans to have completed three office buildings at a new project in South Lake Union.

Vulcan has said it has one unnamed tenant in mind for its so-called Terry-Boren project, which would ultimately total 1.5 million square feet on six blocks. Many in the local real-estate community believe the tenant is Amazon.

A landlord typically does not market office space "this far in advance unless the occupying tenant has indicated they will vacate upon lease expiration," said Kip Spencer, a founder of Officespace.com and executive at NuMark Office Interiors.

Amazon declined to comment, and Johnson said he "can't comment on what Amazon is doing, one way or the other."

The company occupies about 640,000 square feet of office space in and around downtown. It moved to the 1930s-era PacMed building in the late 1990s.

"They've been a great tenant to have," Johnson said. "There's no reason why we'd want to see them go."

He said tenants in need of that much office space — room for at least 1,200 workers — tend to start looking three years out, meaning he needs to market it now to have it filled by mid-2010.

Amy Martinez: 206-464-2923