UnionBanCal Corporation—which owns Union Bank—announced it’s entered into an agreement to buy the Santa Barbara-based Pacific Capital Bancorp for a reported $1.5 billion.

Pacific Capital operates Santa Barbara Bank & Trust, which runs 47 branches in California, including three in San Luis Obispo County: two in San Luis Obispo and one in Paso Robles.

There’s no word about how local branches might be affected.

In a prepared statement, UnionBanCal—owned by the Bank of Tokyo—said the acquisition will assist in expanding its geographic footprint on the Central Coast, becoming the leading bank in the Santa Barbara metropolitan area, fourth in the Oxnard-Thousand Oaks area, and a top-five institution in the greater Central Coast region.

 “Santa Barbara and the Central Coast are very attractive regions for banking and wealth management services, and represent an important geographic expansion for Union Bank,” said Union Bank CEO Masashi Oka.

The acquisition is scheduled to be completed in the fourth quarter of 2012, pending shareholder and financial industry regulator approval, according to a company news release.

Union Bank, which is headquartered in San Francisco, operates 414 banking branches in California, Oregon, Washington, Texas, and New York. It held approximately $89.7 billion in assets, as of Dec. 31, 2011.