Earlier this year, a report drafted by structural engineer David Bonowitz identified 488 suspected soft-story buildings that have at least three residential units, a total of 5,123 housing units representing about 16 percent of the city's total housing stock -- similar to the percentage of earthquake-vulnerable homes in Oakland and San Francisco.

City officials originally declined to post the list publicly, calling it a preliminary way to take stock of buildings that might be at risk rather than a definitive roster of vulnerable housing units. Some of the buildings, following a detailed inspection, may be deemed safe and not in need of retrofit work. Citing unexpected interest from the public, building officials released the list of addresses Thursday evening -- albeit with most of the survey details removed.

The list , which the Voice acquired through a state Public Records Act request in July, was put together by a hired consultant with the task of figuring out which properties in Mountain View appear to be of so-called "soft story" design. Soft-story buildings have structurally weak ground floors that puts them at a heightened risk of collapse in a strong earthquake.

The city of Mountain View released a list of hundreds of addresses of residential buildings that could be vulnerable to collapse in a major earthquake -- more than 5,000 rental units spread across the city.

The blue dots represent suspected soft-story buildings in the city's survey, with the size of the dot reflecting the number of housing units the building contains. A searchable and interactive version of this map is available here: https://public.tableau.com/profile/mark.noack#!/vizhome/SoftStory-MountainView/Dashboard2

Residential buildings identified in the study range from one single vulnerable housing unit to as many as 184 units on a property. In the Shoreline West neighborhood, for example, the study found 53 small multi-unit rental properties totaling just under 200 housing units are potentially at risk. Larger buildings with more than 40 units, primarily along streets that including Latham Street and Escuela and Montecito avenues, account for 1,700 of the soft-story buildings listed.

The city-commissioned survey shows that the vast majority of the potentially hazardous homes follow a similar trend -- two- and three-story rental housing structures built between 1950 and 1980 with parking on the first floor and housing units on top. While building designs and layouts vary significantly, more than half of the 5, housing units have what's called a "long side open," meaning that the structural vulnerability is along the long side of a rectangular building.

The study was meant to pave the way for a discussion by Mountain View City Council members in June to consider a soft-story retrofit program to improve the safety of residents in vulnerable buildings, but was bumped from the agenda. Council members are scheduled to revisit the item on Tuesday, Sept. 4.

The study session is set for the end of the City Council meeting that begins at 4:15 p.m. on Tuesday, Sept. 4, in the Council Chambers at 500 Castro St.

Another key concern is how much the retrofit work will cost property owners, and how much of those costs can be passed on to tenants through a rent increase.

The release of the information comes just a few days before the City Council is scheduled discuss whether a to impose a voluntary or mandatory retrofit program for soft-story structures. The study by Bonowitz recommended that if the council favors a retrofit program, it would likely need to require mandatory compliance in order to achieve "substantial citywide risk reduction."

Building officials cautioned that the study is preliminary and subject to change, and that not all of the units on each identified property may be at risk. Mountain View is also on fairly stable ground compared to places like Foster City, meaning the liquefaction zone is not a significant factor in terms of public safety.

A large portion of the city, encompassing about a quarter of the housing identified in the report, are on ground prone to liquefaction, which increases the risk of buildings being damaged in an earthquake, according to data from the U.S. Geological Survey. The liquefaction zone includes nearly all of the city north of Central Expressway, along with portions of the Old Mountain View and Shoreline West neighborhoods.

City releases data on homes at risk in an earthquake

Council to consider retrofitting rules affecting hundreds of soft-story buildings in Mountain View