I remember the January 17th, 1994 Northridge quake vividly as I was shaken awake in the most violent earthquake I have ever experienced. Located in West Los Angeles, between the collapsing I-10 Freeway bridge to the East and a collapsing medical building to the North, our home suffered a cruel fate, having moved off its foundation to such a degree as to be "red tagged" as being unsafe for human occupancy. An experience that I would rather not repeat in my lifetime.

And yet as I watched the television news, I see Dr. Lucille Jones, the noted seismologist who works for the United States Geological Survey and a member of the California Seismic Safety Commission, briefing a seismic safety panel gathered in Coachella Valley. Her words are extremely ominous as she describes the consequences of a large quake centered in California's Coachella Valley, southeast of Los Angeles, and located between two powerful and dangerous faults: the famed San Andreas fault and the equally powerful San Jacinto fault.  What made this briefing even more scary was the fact that she was describing an area that was approximately 300 years overdue for a major quake. Not one to be taken lightly, she described a quake scenario that could potentially topple buildings in Los Angeles.

One the day of the presentation, a magnitude 4.6 quake struck tens of miles from my present home. Enough to raise momentary concern as it was centered in the far reaches of Northridge. Followed a few days later by a more gentle 3.5 magnitude temblor.

Which made me think of my late friend Nick, a movie special effects guru and certified welder and his rants on welds in certain Los Angeles high-rise buildings. Nick was convinced that hundreds of welds were potentially compromised and that, at this late date, nobody was routinely re-inspecting the weld joints. Laughingly he proposed a weld-inspection business where everybody from the owner, the insurance company, the contractors architects and engineers hated you. Joking it was like being the fire marshal or designated safety officer on a small budget movie.

Considering that my sister works on the 18th and top floor of a West Los Angeles high-rise building, I decided to revisit the subject of high rise buildings and their suitability to ride out a severe jolt.

It all started with the January 17, 1994 Northridge Earthquake which registered a magnitude of 6.7 and lasted for approximately 15 seconds. When the shaking stopped, 51 people were dead and 9,000 people were injured. The loss of life was limited due to the quake striking at the early morning hour of 4:30 a.m when most people were still at home. This quake has been the largest and costliest quake in recent times, with $44 billion dollars in damage, 25,000 dwellings uninhabitable, 7,000 buildings red-tagged (no occupancy), 22,000 buildings yellow-tagged (limited access), 9 hospitals closed, 9 collapsed parking  garages, major structural damage to 11 roads into Los Angeles forcing closure, 2 bridges on the I-10, 3 bridges on the SR-118, 2 bridges on the I5 and  2 bridges on I5/I14 interchange collapsed.  22,000 people were left homeless.

No doubt a major catastrophe. But one, according to Dr. Jones, that may  be exceeded by a projected Magnitude 7.8 striking in the Salton Sea between the two Coachella faults.

But my  real concern involves a large number of "moment steel frame (high-rise) buildings" which suffered large and unexpected cracks. 

From an article written by Greg Brower which appeared in the 1994 LA WEEKLY NEWS...

"When the Northridge quake awakened Los Angeles on January 17, 1994,  it was considered at 6.7 magnitude a relatively moderate shudder. However, because of its location, it was the first true seismic test for many of L.A.'s 1,500 steel-frame buildings. At first glance, most edifices seemed to fare well, but a disturbing trend soon surfaced: Many of the interior beam-to-column connections had cracked, in some cases splitting all the way through. The problem first came to light in structures still under construction, like the Getty Center, which was then just completing steel framing. Engineers there found a series of cracked connections and decided to replace all of its original welds. Owners of completed steel-frame buildings thus learned of the threat, but determining the status of their own welds would require breaking through plaster or concrete just to get a look. Still, the damage had been done -- the long-standing myth of the seismic invincibility of steel has been questioned ever since."

Was there something about the construction of certain steel buildings that caused problems. You bet.

The cracked connections in the steel structures, known as "welded steel moment frame"  (WSMF) buildings seemed to have a single factor in common, up to 99% of the connections were all welded with a particular welding method and using a particular welding material which had been previously approved for the use under the city's rigorous building code. However, as subsequent events demonstrated, the welding material and the process were inadequate to survive a moderate earthquake. Perhaps the capabilities and the performance of the welding method and materials were oversold by welding vendors who had no experience with seismic properties of the goods that they were selling as being a cost effective construction technique.

Even after noting the cracked connections, there was additional controversy over who would pay for the repairs and even what constituted  a safe practice of repair and replacement.