Is Victoria ready for the Big One?

By Katherine Gordon, September 2011

Will the city have what it takes to minimize loss of life and property damage when the Big One hits? Not if expensive, politically driven band-aid measures are the norm rather than comprehensive resilience planning focused on well-considered priorities.

When a catastrophic earthquake struck Christchurch, New Zealand on February 22, 2011, thousands of buildings and homes were destroyed; 181 people died. Christchurch was almost completely unprepared for that level of devastation. The cost of rehabilitation is likely to be around $11 billion (CAD). 

Six months later, Christchurch’s central business district, where tattered high-rises still cling to their foundations and the rubble from collapsed buildings litters the streets, remains cordoned off from business owners and residents who ran for their lives that day, leaving everything behind. Repairs to the sewer system are incomplete, and thousands of people still have to use chemical toilets and communal Portaloos. Insurance companies are scrambling just to assess the claims pouring in, let alone pay them. Most people won’t see a penny for months, possibly years.

Immediately following the quake, many roads were impassable. Grocery store shelves were empty, their ruined contents scattered in the aisles. It was very difficult to buy food, water, diapers, or gas—anything that people normally stop for on the way home from work. Few people were able to go to work anyway, as hundreds of businesses lay in ruins. Many will never return. 

 

Not every earthquake is created equal

Could Victoria find itself in the same situation? What happened to Christchurch is certainly a scenario that we could face if a major earthquake struck the city tomorrow. But before anyone panics, it’s important to understand what that actually means. 

There are three types of earthquake that might occur in the vicinity of Victoria. Megathrust or subduction quakes, triggered when two tectonic plates converge and one starts to move over the top of the other, are the most powerful. Subcrustal earthquakes, occurring within the subducting or lower plate, typically occur 50-70 kilometres below the surface. The third kind are shallow crustal quakes, which have the potential to cause the most damage. 

The last massive subduction earthquake hereabouts took place off Vancouver Island in 1700. In 1946, a large, shallow earthquake, Richter magnitude 7.3 in size, struck northwest of Courtenay. Southern Vancouver Island escaped damage, however, because of its distance from the epicentre. The greatest earthquake in Canadian recorded history was a magnitude 8.1 shake near Haida Gwaii in 1949. Cows were knocked off their feet and some chimneys toppled, but again, the damage was fairly minor.

In recent times, the nearest Victoria has come to a major earthquake was the Nisqually shake that struck just north of Olympia, Washington in February 2001. No-one was killed, but many older brick-and-mortar buildings near the epicentre, including schools, suffered significant damage. The cost to Seattle of structural repairs surpassed $2 billion US.

 

The aftershocks of Nisqually

Not every Victoria resident felt the Seattle quake, but no-one has since escaped the much greater impact it had on their tax bills. The provincial government, fearful of negative political backlash if anything should happen to vulnerable school buildings in British Columbia, committed $1.5 billion in 2005 to an upgrade program. A report that a $250 million seismic upgrade to the Legislature is required has been quietly shelved, at least until the school upgrades are complete, but other one-off measures triggered by the spectre of a potential Nisqually-type earthquake have included a $3.1 million seismic upgrade of Victoria’s City Hall and, of course, the impending multimillion-dollar replacement of the Johnson Street Bridge, final price tag yet to be determined, but likely more than the $77 million budgeted.

 

Planning and priorities

Can measures like these be justified based on Victoria’s seismic risks? And where do they fit among the overall priorities for building a more earthquake-resilient region? Why has the Johnson Street Bridge trumped hospital upgrades, say, or shoring up the city’s ancient and vulnerable water and sewer infrastructure, in the overall priority list?

It may be because Victoria has no priority list for seismic upgrades. The City has the opportunity to apply the accumulated experience of Christchurch, Japan and other recently devastated locales to a cost-effective and comprehensive seismic resilience plan that would significantly reduce the kinds of impacts those places have suffered, and that sets out well-considered, defendable priorities. But there’s little evidence it’s doing that. 

Both the provincial government and the City of Victoria, like other municipalities in the Capital Regional District, do have extensive emergency management programs in place focusing on post-disaster coordination and recovery efforts. 

That’s vital, of course. But dropping and rolling exercises and flashlights in earthquake kits won’t help much if buildings are collapsing before people can escape from them, the water is cut off, and the local food supply runs out after three days, as is expected if transportation links to the mainland are unserviceable. 

That’s the reality that every municipality in the CRD could be facing, emergency plan or not. What about doing more to maximize the region’s resilience to an earthquake and to reduce its impact before it strikes? 

When it comes to the City of Victoria, detailed geological seismic risk information has been available for a number of years. In 2006, a thorough hazard risk assessment was also undertaken for the City, identifying earthquakes as one of the municipality’s five highest-risk exposures. But it appears there is still no plan in place for how best to allocate limited municipal government resources in dealing with the earthquake hazard, or for the adoption of robust policy initiatives aimed at reducing the risks. 

Shouldn’t the City of Victoria, for example, be prioritizing upgrades to its water and sewer infrastructure, identified in the draft official community plan (OCP) that is currently under review as needing imminent replacement at significant capital cost? The Sooke Dam, from which Victoria draws its water, has been seismically improved. But shouldn’t the city be trying to establish an earthquake-proof source of drinking water closer to downtown, as Vancouver has done? What about ramping up support for local food production? 

Prudence would also suggest adopting the highest seismic standards in local building codes, as Vancouver has also done, instead of the minimum levels. The objective of seismic standards in building codes is, after all, to ensure public safety in the event of an earthquake. Shouldn’t every building owner in Victoria be compelled to implement seismic upgrades, not merely be offered tax incentives to do it as currently contemplated in the draft OCP?

There is nothing to indicate that steps like these are on the radar. But then, the City of Victoria is also keeping its cards very close to its chest. Focus Magazine has requested, through provisions of the Freedom of Information and Protection of Privacy Act, the two seismic risk assessments the City completed in 2010 on Fire Station #1 and the Crystal Pool, and a third, recently completed study for other City-owned buildings. The City has refused to release these completed reports. What is there to hide?

 

What the City says about the Big One

It is difficult to ascertain whether local authorities have a realistic grip on the likelihood of an earthquake affecting Victoria and its potential impacts. In public documents, City staff state the probability of a major earthquake in the region in highly simplistic terms that are virtually meaningless in the context in which they are used. 

The current draft OCP states, for example: “There is a 32 percent likelihood of a damaging earthquake event in the city before 2054.” In the publicity that the City generated to justify the expense of replacing the Johnson Street Bridge, it similarly stated that “recent studies have indicated that there is a 30-35 percent probability of a major earthquake occurring in Victoria in the next 50 years,” described as being similar to an earthquake “in the range of Magnitude 7.0-7.9.” But the material doesn’t go on to explain how these estimates were derived, or what they mean. 

In fact, the probability models from which the City has derived its figures are based on intensity, not magnitude (more on this below). Earthquake probability estimates are also not precise calculations. Dr Garry Rogers, a senior research scientist with the Geological Survey of Canada (GSC) and an adjunct professor in earth sciences at the University of Victoria, says that such estimates should be given considerable leeway. “It would be better to use a figure like 30 percent, or about one chance in three of the predicted event occurring over 50 years—something that doesn’t suggest that the number is known to the precision of 32 percent, which it simply isn’t.” 

For the average citizen of Victoria, it’s difficult to place much confidence in the figures quoted by the City, let alone understand what the hazard and risks really are.

 

An earthquake measurement primer

Magnitude is a common way to convey size, but is the least useful measurement of actual risk to planners and engineers. It is also the least meaningful term to use to convey to citizens what will happen in different scenarios. Intensity of a shake, and ground level of shaking, says Rogers, are more appropriate terms to use. 

Magnitude, intensity and level of shaking aren’t interchangeable terms. The Richter scale measures magnitude, which is the amount of energy released at the epicentre of a quake. “Earthquakes only have one magnitude,” explains Rogers. “It doesn’t change depending on your distance away from the epicentre. Think of a 100-watt light bulb, for example. It’s always 100 watts, whether it’s in the lamp next to you or in the room next door. A magnitude 7 earthquake is always a magnitude 7, wherever it is and wherever you are in relation to it.” An earthquake has to have a magnitude of 7 or greater to be considered “major.” Only a tiny portion of shakes fall into that category.

The Modified Mercalli scale measures intensity by describing the impact of a quake at a specific location. Unlike magnitude, intensity does change depending on proximity to the epicentre, much like the perceived brightness from a light bulb depends on how far away it is. Many other factors also influence the measure of intensity, including the depth of the quake, and the nature of the geology and soil of a particular location. Poor, swampy soil and infill are prime culprits in increasing the impact or felt intensity of a quake; rock is much more stable.

MM1 on the Mercalli scale is essentially zero impact. MM5 would be felt by most people, but would not have any significant impact. MM7 will see the onset of damage to some weak structures. MM8 is the point where things become much more serious, with more widespread structural damage occurring. At MM12, it’s game over.

The Mercalli scale is the oldest seismic measurement tool in use. It is still helpful as a descriptor, says Rogers, but since seismographs were invented that could measure shaking in terms of gravity acceleration percentages, it is the latter that is used by seismologists and engineers for determining with greatest precision the potential hazard, at specific sites, from various levels of shaking that might occur at different levels of intensity at those sites. 

The three different measurements all have their uses in different contexts, says Rogers. “But it’s important not to mix them up.” Using simplistic one-size-fits-all magnitude figures in planning and public communications isn’t advisable, he says: “That’s dangerous. It’s not defensible and doesn’t help people understand the problem.”

 

The real probability of a major earthquake in Victoria

Significant historical and geological data are available in BC to seismologists, who can use hazard models based on that data to develop the probability of the three different kinds of earthquakes we have here occurring over different periods of time, at different levels of intensity, and within the vicinity of general areas such as south-western coastal BC. The higher the potential intensity level plugged into the model, the lower the probability it will occur.

According to the Geological Survey of Canada, the nearest subduction earthquake source zone does not extend beneath Vancouver Island. A subduction quake is the least likely to occur within our lifetimes, with an expected probability of anywhere between 10-15 percent over the next 50 years of a shake impacting Victoria at an intensity level of MM7 or more. The GSC estimates that the likelihood of a level of shaking from a greater crustal or sub-crustal earthquake that will cause damage to weak structures (MM7) over the same time period at about 20 percent. 

In practical terms, as Rogers has already pointed out, that means a more or less one in three chance in the next five decades, give or take a couple of percentage points either way, of an earthquake that could cause some damage to weak structures somewhere in the vicinity of Victoria. But that doesn’t mean there’s a one in three chance of that earthquake actually occurring in Victoria. 

Trying to provide specific predictions as to where potential earthquakes will occur, or even what intensity they will be, is risky business. Maiclaire Bolton, a Canadian seismologist working with California-based Risk Management Solutions Inc, is a graduate of UVic’s Earth and Ocean Sciences program and the former head of the seismic program at Emergency Management BC. Bolton says: “We can state the probability of an earthquake occurring, and even its size, with a fairly high degree of accuracy, but stating it will actually occur in Victoria is another matter. That’s simply impossible.” 

 

What does all this mean in terms of assessing seismic risk?

“It’s nonsense,” Rogers states bluntly, “to use magnitude when talking about risk, or what a certain piece of infrastructure can handle. A 6.5 magnitude shallow earthquake ten kilometres away can do as much or more damage locally as a 9.0 subduction earthquake 100 kilometres away,” he continues. “Take the Blue Bridge in Victoria, for example. It’s what level of shaking it will be able to withstand in an earthquake that matters, regardless of whether it is a small-magnitude quake close by or a larger one further away.”

The most useful way to undertake risk assessment is to first understand the level of shaking that will cause the collapse of a structure or similar devastation—the hazard, as Rogers describes it—then base decisions on priorities for remediation on the probability of that level of shaking occurring. 

“The level of shaking is usually measured as a percentage of the acceleration of gravity caused by ground movement,” explains Rogers. That sounds very technical, but in real terms people can start to feel earthquake shaking at about one-tenth of one percent of gravity. “Structures in the Nisqually quake experienced a maximum level of shaking of about 20 percent of gravity, with corresponding damage. In Christchurch, the shaking was so bad it exceeded the acceleration of gravity. The level of shaking, measured this way, is what engineers and planners should be using in making decisions on risk mitigation. It’s what’s used in the building codes.” 

 

Is any seismic resilience planning happening in Victoria?

Southwestern BC is one of the most seismically active regions in the country, and becoming more earthquake resilient is not only appropriate but essential for public safety. 

But current initiatives in that direction appear haphazard at best. Seismic risk mitigation goals in the City of Victoria’s draft OCP are vaguely worded and high-level, lacking any tough measures behind them. Budget priorities are unclear. 

By comparison, the City’s 2006 hazard and vulnerability assessment, commissioned on behalf of the Victoria Emergency Management Agency with the goal of using the information as the basis for allocation of resources for priority risk mitigation, is clear about the need for action and contains 18 recommendations for mitigation initiatives. 

Some of those are questionable, however. The VEMA report recommends upgrading or replacing the Johnson Street Bridge, for example, despite also pointing out that the Point Ellice Bridge, a short distance away, has already been seismically upgraded and that water, gas and telecommunications lines coupled to that bridge are expected to be earthquake-resilient. 

Other recommendations have made it into the draft OCP, such as encouraging property owners to upgrade through incentive programs. The latter document also identifies the need to focus seismic mitigation measures on areas of vulnerability identified on local hazard maps. The draft OCP even forecasts the need for robust local sources of food, energy and materials to be on hand in the event of an emergency.

Whether other recommendations arising from the VEMA report have been implemented, including the creation of a building inventory and map of high-risk structures and the conducting of a regional soil study, is difficult to ascertain. VEMA Director Rob Johns did not return phone calls requesting an interview, and the City, as mentioned above, has refused to release any of its completed risk assessments. An urban design discussion paper produced by the City in May 2010 outlined Victoria’s strengths and weaknesses in anticipation of updating the OCP. If the discussion paper takes into account the hazard assessment, it isn’t obvious. There is only one reference to seismic risk management in the 67-page document, and that is a note that the Bay Street Armouries building should be seismically upgraded. 

In the meantime, the OCP does not identify specific priorities, and does not incorporate an overall comprehensive seismic risk management plan. It does not identify why the Johnson Street Bridge was deemed a priority for upgrade over other critical infrastructures. Nor does it cross-reference seismic risk management in its development and land management sections—or in its infrastructure section, or any other part of the document. 

It also makes no reference to what seismic standards the City plans to subscribe, either in terms of retrofits or new development. Since 1964, building codes have contained minimum seismic standards, and the national code was updated as recently as 2010. Those standards are all about public safety: it’s impossible to legislate into existence a quake-proof building, but it is possible to build in safety mechanisms aimed at ensuring people can get out of the structures in one piece, without the structure collapsing on them. 

The provincial building code has been adapted from the national code. While it contains some mandatory seismic standards, they do not apply in all cases. Maiclaire Bolton identifies a significant problem in the code for Victoria in particular, saying that many smaller multi-family apartment buildings (three storeys or less in height and less than 600 square metres) are also exempt from some of the code’s seismic standards. 

“All you have to do is walk up and down [lower] Cook Street, and that applies to almost every apartment building,” observes Bolton. “They’ve been built to that precise dimension to beat seismic code provisions. Many of them also have open parking underneath. Those buildings are very high vulnerability.” That’s disturbing, especially after reviewing Victoria’s hazard map: the lower part of Cook Street is coloured an uncompromising red due to soil issues.

Municipalities can choose to adopt higher standards than the code, and Vancouver has done so. Victoria has not followed that path to-date, preferring to encourage building owners to upgrade rather than force them to do so. Nor does it have in place any hard-nosed restrictions on expanding development on vulnerable soil—which, according to the hazard map, is what a great deal of downtown Victoria is built upon (have a look at Map 14 in the draft OCP, for example). 

Credible resilience assessments require an analysis of not only the soundness of structures on a landscape, but the ground on which they are built. Rock is good; sand, mud and peat are all prone to liquefaction. In a paper entitled Earthquakes Don’t Kill People, Buildings Do, Dr Tark Hamilton of Camosun College’s geosciences department notes that the most vulnerable building sites are on slopes with thick, unconsolidated sediments. He cites Beacon Hill Park, Dallas Road and—again—Cook Street Village as being high-risk in this regard. Recalling that the intersection of Vancouver and View Streets is built on what was a peat bog at the time of settlement, he notes that as the intersection became subject to heavier and heavier traffic, the peat in the centre once bulged as high as 1.3 metres higher than the curb. “Think of sitting on a water bed and watching it bulge up beside you,” he says. “When hydrous, unconsolidated sediments are subjected to long period earthquake waves, they move in standing waves that can have amplitude of a metre or more. Pity anything built on this as bulges move around and horizontal and vertical do not keep constant orientation. It is hard to keep buildings standing as they act like the Leaning Tower of Piza.” Victoria is continuing to build, he says sombrely, in harm’s way.

Gerry Buydens, a structural engineer and former manager of the provincial government’s seismic mitigation program, was involved in the early stages of BC’s seismic assessment of schools. “Our thinking back then was that if we found a school wasn’t built on good soil, it was just as well to knock it down, because even if you refurbished it, it was still an old school on bad ground,” says Buydens. “If there’s an earthquake, the building will slump and fall.” Upgrading old buildings constructed on poor, swampy soil—the Legislature, say, and much of the rest of downtown—is tough, and costly. “I don’t think it’s really worth it.”

In addition, says Bolton, governments really need to think more about comprehensive planning instead of knee-jerk reactionary initiatives to individual projects. “You’ve got to step away from one bridge, for example, and move to the big picture. You have to think about moving key assets away from the high risk areas, and prioritizing essential services instead.” 

That’s exactly what the provincial government has done, relocating its emergency planning office to a safer location at Keating Cross Road. The City has less choice in that regard when it comes to City Hall. All the same, there’s little question that it will be vitally important for there to be a secure headquarters for civic management in an emergency. Victoria’s hazard maps indicate that there are areas within municipal boundaries that are much safer to locate core services and protect them than the downtown core. The location of City Hall itself is on a blurry moderate-to-high-risk section of the map. But whether it really is sitting on poor ground or not, and whether the City has simply thrown good money after bad in upgrading instead of moving locations, we simply don’t know, and won’t until the City’s risk assessment is released publicly. 

Vancouver engineer Leon Bell, who has undertaken numerous seismic assessments in Victoria, adds that about 90 percent of the damage caused by earthquakes in North America is to non-structural systems within buildings—electrical wiring and plumbing, for example—not the buildings themselves. “Only a small percentage of high-risk buildings actually fail,” observes Bell. “Conversely, low-risk buildings with no seismic mitigation of the non-structural systems can and do suffer significant damage. This is a very serious economic issue.” But again, there is nothing to suggest that the City understands that statistic, either. 

 

Priority-setting and the fear factor

Dr Kenneth Elwood, an associate professor in UBC’s civil engineering school, is one of 26 researchers with the Canadian Seismic Risk Network, a group of academics working on lower-cost alternatives to dealing with seismic mitigation. In April this year, Elwood told National Post reporter Tristin Hopper that mitigation is simply too expensive “to jump at renovating every building. If you look at the probability of dying in an earthquake versus all the other things you could die from, it makes you stop and think where you should be spending your resources.”

The CSRN has numerous ideas for cost-effective measures to shore up buildings that could cut costs by up to 50 percent. Those include state-of-the-art, fibre-reinforced plastic “wallpaper,” ten times stronger than steel, that can be used to wrap quake-susceptible buildings. CSRN’s Perry Adebar pointed out: “By being clever—not just throwing money at it—one can do repairs that will make a significant difference without spending a fortune. More thinking, less bricks and mortar.” In a similar vein, Tark Hamilton says: “The goal is to educate people about what they can do to prepare, reduce risk, improve public procedures, and not to scare them or needlessly destroy real estate value, when ultimately earthquakes are unpredictable.”

But the fear factor is an effective strategy when governments want to sell a project: witness the Johnson Street Bridge. Fear also drove the very expensive provincial school upgrade program—an easy sell to scared parents. No-one wants to see children die in a collapsed building, says Gerry Buydens, but at the same time, it doesn’t make a lot of sense to be spending so much on buildings that are unoccupied three-quarters of the time. “What about the other places where kids spend all their time—like downtown malls and their own homes?”

Buydens and Bolton also point out that an immediate and relatively cost-effective way to improve public safety would be to encourage people and businesses to anchor furniture to walls. Buydens points out that there could be as much risk of a child being hurt by a loose vending machine tumbling down a set of stairs as being hit by falling bricks. In Christchurch, one infant died when a heavy television set fell from its stand and landed on top of him. In Japan, video footage showed fully-loaded filing cabinets falling on workers with nothing to protect them. It’s a cheap, straightforward public education program that could begin tomorrow, with a real likelihood of saving lives. 

 

A once in a lifetime chance

The plans to rebuild Christchurch are expected to take at least 15 years to be implemented, given limited resources. There is much discussion in that city about how to avoid repeating the mistakes of the past—moving key services away from the vulnerable downtown core, for example, preventing further dubious development in unsafe zones, and making rational choices about priorities: the right way to rebuild the city in the best possible way, keeping in mind that another quake could hit at any time, and understanding in very real terms what that means in practice. 

It would be a very good discussion for every municipality in the CRD to have. For Victoria, a good start would be to publicly release the three seismic risk assessments that have been completed before November’s municipal election, so that citizens have some time to absorb their contents and question candidates on their understanding of the risks and their proposed strategies for dealing with them.

But whether Victoria’s civic leaders are up to that discussion, before they are forced to confront it, remains to be seen.

Expat Kiwi Katherine Gordon arrived in New Zealand for a family visit seven hours before the February 22 earthquake struck in Christchurch, and was able to witness the immediate aftermath firsthand. Several months later, she continues to observe from a distance the ongoing pain of a city almost completely unprepared for what hit it that day.

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