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Earthquakes: Is Christchurch a wake-up call for Los Angeles?

Once more we are faced with our own mortality in the face of a significant earthquake. Of course, engineers in the various departments involving building & safety assure us that “modern codes” have incorporated findings from past earthquakes and theoretical simulations. BFD – it’s not the modern buildings that concern me, but those older buildings which may have never been fully inspected and mitigated and those which have been mitigated to the lowest possible compliance level needed to pass inspection.

Once again, the Los Angeles Times highlights the issue …

“New Zealand quake raises questions about L.A. buildings”

“Concrete-framed office buildings, like those on Wilshire Boulevard near the Hollywood fault, are similar to structures devastated in Christchurch's 6.3 quake.”

“The level of devastation from this week's earthquake in New Zealand has some California scientists saying that the state's seismic building codes should be reevaluated to address the striking structural failures seen in Christchurch.”

“In New Zealand, the quake destroyed many buildings of the types that California officials have long said are most vulnerable in a major temblor: Older unreinforced brick buildings and concrete-framed office buildings erected in the 1960s and '70s. There are thousands of such buildings in the state, and many have not been retrofitted to make them less vulnerable to shaking.”

Not to be a naysayer, but how many seismic studies have been performed on buildings in the Hollywood corridor – especially in an area which has potentially been further compromised by an underground subway?

Knowing is not acting …

It’s not like the civil engineers in Christchurch were unaware of the potential for earthquakes. Here is a snippet from the 2000 Hopkins Lecture titled “Improving the Resistance of Structures to Earthquakes” as delivered by Emeritus Professor R. Park, Department of Civil Engineering, University of Canterbury.

The past occurrence of earthquakes in New Zealand and the likelihood of a major earthquake in Christchurch are considered. The causes of damage by earthquakes are discussed and typical possible types of damage to building and bridge structures are described with reference to the 1995 Kobe earthquake. The design of building and bridge structures for earthquake resistance by the ductile design approach is covered, including performance criteria, structural configuration,
design seismic forces, mechanisms of post-elastic deformation, capacity design, detailing of reinforcement for ductility and control of deflections. Design using base isolation and mechanical energy dissipating devices is also outlined. The extensive use of precast concrete in buildings in New Zealand is described. Finally the seismic assessment and upgrading of old structures and the earthquake resistance of lifelines of communities (transportation, utilities and
communications) are briefly considered

The conclusions include this statement:

“New Zealand has had major damaging earthquakes in the past. It is fortunate that
almost 70 years has elapsed, since the 1931 Hawke’s Bay earthquake, without a
major earthquake striking an urban area. However, New Zealanders must not be
complacent in their consideration of earthquakes
. The attitude or belief ‘that it will
not happen to us’ or ‘it will most likely only occur in Wellington’ needs to be
. There is a 65% probability that Christchurch will be effected by a major earthquake over the next 50 years.”

It’s more than the type of the building …

Of course, the energy unleashed by the earthquake, its location, duration and the type of soil under the building are also significant factors which can greatly affect the potential of catastrophic failure and loss of life. Not to mention the impact of nearby construction, drainage and ground covering.

Bottom line …

The probability of a major quake in Los Angeles is well-known. The seismic research on “dangerous buildings” has been performed and the risks of older buildings are well-known.

But the financial burdens on the building owners and their ability to utilize their political connections to avoid in-depth inspections and the possibility of incurring enormous mitigation costs are also well known.

So, in the final analysis, life is a gamble – a gamble that can be mitigated by being aware of – and avoiding -- those buildings which pose a significant threat. Or as a famous Cal-Tech researcher once said: Earthquakes don’t kill people, man-made structures kill people.

-- steve

Reference Links …

New Zealand quake raises questions about L.A. buildings - latimes.com

Some of my previous blog entries on the subject:




Earthquakes: A reminder of a deadly question ...

A reminder …

“On January 17,1994, an earthquake measuring 6.8 on the Richter scale caused heavy damage in the Los Angeles area This earthquake, referred to as the Northridge earthquake, left 61 people dead, 18,480 injured, and 25,000 homeless. More than 55,000 structures were damaged, of which
1,600 were left uninhabitable. The earthquake also caused significant damage to the area’s extensive freeway system, resulting in closures at seven locations. According to the Federal Emergency Management Agency
(FEMA), the earthquake, causing estimated damage totaling $13 billion to $15 billion, was the nation’s second largest disaster ever in these terms and resulted in the largest number of applications for disaster relief in the agency’s history.”

Well worth reading …

L.A Buildings - Earthquakes - Human Tragedy and those infamous Self Shielded Flux Cored Wires

“This story has it all. Lincoln Electric a Cleveland based major weld equipment and consumable manufacture has major weld product problem in a severe earth quake. The selection by California engineers of unsuitable weld consumables for construction project. Cleveland voters sending donations to California politicians. Tax payers stuck with the bills. Lobbyist, Lincoln and FEMA connections. A generous grant of millions to a company that did not ask for it. The possibility of future buildings designed to with stand an earth quake waiting to collapse and let's not forget, lives that were lost and lives that may be lost in the next L.A earthquake. If this was a movie I would call it ‘The greatest weld Story Ever’ Told or ‘The Fox who was asked to guard the Hen House.’"

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