SAN FRANCISCO (KPIX 5) — Dozens of San Francisco’s biggest buildings could be at risk of collapse in a massive earthquake, according to a U.S. Geological Survey report uncovered by the New York Times.

One of the buildings is the iconic Transamerica Pyramid on Montgomery St., one of nearly 40 steel-frame high-rises constructed in San Francisco between 1960 and 1994. It a period when builders switched from bolts and rivets used in previous steel buildings to welding.

The problem with that technique came to light in 1994 when the Northridge Earthquake fractured critical joints in more than 60 steel-frame buildings in Los Angeles.

The building code was re-written after that, but by then, dozens of San Francisco high-rises had gone up using the faulty technique, including the Hartford Building at 650 California and 211 Main Street, which houses the New York Times’ Bay Area bureau.

Salesforce West, the 43-story building at 50 Fremont St. also made the list. It sits directly across from the brand-new Salesforce Tower – which, incidentally, is not a steel-frame building.

Other notable addresses include the old U.S. Bank Building at 555 California St. and the Embarcadero Center, a cluster of four buildings that thousands of people pass through every day.

The Pacific Gas and Electric Building on 77 Beale and the Bechtel Building also made the list.

While the Hilton Hotel near Union Square was also singled out as potentially unsafe, the managers there told the Times the building got a retrofit in 2012.

San Francisco currently requires retrofits for so-called “soft-story” buildings, but it still hasn’t figured out what to do about its potentially faulty steel-frame towers.

Retrofit costs can run into the tens of millions, which is why few building owners have done them.

A bill currently moving through the legislature would require all cities in California to produce an inventory of all buildings that could be at risk in a major earthquake.