One of LA's tallest buildings feared to COLLAPSE when Big One finally strikes California

Fears are mounting that a 749-foot-tall Los Angeles skyscraper could collapse if a historic earthquake eventually strikes the city.

Officials have refused to release seismic reports which detail the Gas Company Tower's ability to survive the long-feared 'Big One.'

Los Angeles County purchased the 52-story skyscraper last year with the intention of moving hundreds of their staff into the city's fifth tallest building.

However, officials suspended a recommended $230 million retrofit for the building that would have updated the 34-year-old skyscraper to modern earthquake-resistant standards.

Gas Company Tower was built in 1991 and is a modern steel building, constructed with a design called a 'steel-moment frame,' which used horizontal beams and vertical columns to form a strong skeleton.

This has alarmed nearby workers and residents, as the skyscraper was erected three years before the magnitude 6.7 Northridge earthquake, which severely damaged several buildings constructed using the steel-moment frame method.

Moreover, California officials did not require Gas Company Tower to be inspected after the Northridge quake, meaning there could still be damage inside the structure that was never found.

With the Big One feared to be drawing closer every year, structural engineers worry that without upgrades, the skyscraper could threaten thousands of lives under the worst-case scenarios for the city.

According to the Los Angeles Times, officials refused to make Gas Company Tower's report public because Los Angeles County is still awarding contracts for construction at the site.

However, the county counsel claimed that the original report was 'being updated with new findings.'

Los Angeles County supervisor Lindsey Horvath added: 'Safety is non-negotiable, and my understanding is that the building already exceeds safety requirements.'

The Los Angeles County's Chief Executive Office told the Daily Mail Tuesday: 'The Gas Company Tower fully meets all City and County seismic codes, and any seismic upgrades would be voluntary.'

Despite the assurances from local government, structural engineer David Cocke pointed out that the Northridge quake caused many of the connections between beams and columns in steel-moment buildings to crack or completely break.

'I don't think it's going to collapse — that's just my opinion,' Cocke said. 'But I can say with a lot of confidence, in a major earthquake, they're not going to be able to use the building unless they do the retrofit.' 

Officials in the city of Torrance, which is also in Los Angeles county, were less optimistic in the chances of steel-moment frame buildings surviving the Big One, a massive earthquake that would likely be around magnitude 7.8 or higher.

'Many of these buildings have not been retrofitted and may be susceptible to similar severe structural damage or even building collapse in a major earthquake,' city officials explained while addressing their own building repair program.

City officials in Torrance also noted that buildings like Gas Company Tower suffered from serious design problems that were exposed by the 1994 earthquake.

'Experts discovered that these buildings suffered from a wide range of flaws resulting from shortcomings in established design and construction procedures, including poor basic connection geometry, poor connection welding materials, and inadequate quality control, among other factors,' the city wrote.

In 2008, officials with the US Geological Survey (USGS) conducted a simulation of what a 7.8 magnitude quake would do if it erupted along the San Andreas fault under Los Angeles.

This hypothetical 'Big One' would cause roughly 1,800 deaths, 50,000 injuries, and $200 billion in damages, according to the Great California ShakeOut.

It would also cause a surface rupture of up to 13 feet, causing significant damage to infrastructure crossing the fault line, such as roads, pipelines, and rail lines.

As for buildings, roughly two million buildings would be affected, with 50,000 buildings completely destroyed or red-tagged, meaning they couldn't house people again.

The report also warned that older, unreinforced structures and high-rises with brittle welds were particularly vulnerable.

Los Angeles County cited financial problems as the reason they stopped the retrofit of Gas Company Tower, complying with modern building codes which account for seismic stress in earthquake-prone California.

The County's Chief Executive Office added that the initial seismic report was 'conducted using the building's engineering plans of record and computer modeling to confirm that the building is code-compliant.'

A spokesperson noted that with this risk assessment done, the county can now figure out what upgrades are needed to survive the Big One and how much those improvements would actually cost.