Sunday, May 26, 2019

A big earthquake near Vancouver is almost inevitable. Are we ready? [Richmond BC, Canada?]

Depending on how big an earthquake eventually hits in Vancouver, and where, means the lack of readiness could be costly.

Cars and people lie crushed under the slabs of a collapsed bridge. Nearby, boulders from a landslide have trapped vehicles and passengers. Emergency personnel pull bodies from the wreckage.
That was the scene last Friday in Vancouver – staged as a test of the city’s preparedness for a real earthquake. Hundreds of staff worked on exercises ranging from community-centre evacuations to the deployment of Vancouver’s urban search-and-rescue team. Mayor Kennedy Stewart said that “people should feel confident” about the city’s readiness.
They should – to an extent. But Vancouver and the entire West Coast are not as ready as they could be. Depending on how big an earthquake eventually hits, and where, that lack of readiness could be costly.
If, for example, a magnitude 7.3 quake hits close to Vancouver, the provincial emergency-response plan forecasts as many as 10,000 dead and more than 100,000 injured. In the City of Vancouver alone, 150 buildings would likely collapse and 4,000 would be so severely damaged they would need to be demolished. Central neighbourhoods, home to older buildings, could be cordoned off for months. Canada’s entire economy would feel the blow, including from the interruption of the half-billion-dollars of cargo and oil shipments that flow through Vancouver’s port each day.
That big an earthquake, hitting the most populated part of the province, is the “worst-case” scenario, according to B.C.’s emergency-response plan. But reports have estimated the odds of a smaller but still significant quake in the region over the next half-century at one-in-four to one-in-three.
Two earthquakes recorded off Vancouver Island, no tsunami risk or damage reported
The odds of a really big one – a magnitude 9 event similar to the megathrust earthquake and tsunami near Japan in 2011 – was estimated by a B.C. auditor-general’s report at one-in-10 over the next half-century. That could occur along the Cascadia subduction zone, where two tectonic plates collide. It runs offshore from Vancouver Island to northern California. The last big quake in this area was in 1700.
A major challenge for earthquake planning in B.C. is that, while earthquakes are not unusual in the province or in coastal waters, major quakes on land and near population centres are rare. Few British Columbians remember the last big one, a magnitude 7.3 on Vancouver Island in 1946. The urgency is not obvious. However, the 2011 earthquakes in Japan and near Christchurch, New Zealand, sparked governments here to renew their efforts.
One example of the progress that has been made is an offshore early-warning system developed by University of Victoria’s Ocean Networks Canada. Covering the northern third of the Cascadia subduction zone, it is a first in North America.
Once in operation, the system will provide a crucial minute or two of warning to gird for disaster – similar to systems in Japan. That could give time for everything from diverting aircraft and slowing trains to opening bay doors at fire stations and alerting citizens. It’s a necessary earthquake-protection measure, but it isn’t yet up and running, and the B.C. government doesn’t have a plan for when it will be.
It’s not the only area where Canada has moved forward, but still lags. Seattle has pushed ahead on rules to retrofit older buildings susceptible to collapse, following the lead of cities in California. Vancouver has no plans to do the same.
Among citizens, readiness varies. Two-thirds of homeowners in southwest B.C. have earthquake insurance, as do most businesses. A 2014 Statistics Canada survey showed that 54 per cent of households in the Vancouver area have emergency supply kits. In the Victoria area, it was 63 per cent.
Progress has been made – but more is still needed. B.C. spent $17-billion from 2000 through 2015 on seismic upgrades for public infrastructure. But in the province’s schools, the plan to retrofit high-risk buildings is slated to continue until 2030, with 176 schools on the waiting list.
Building codes have long ensured that new structures will not collapse during an earthquake, but some new buildings may suffer enough damage to be unusable, as happened in Christchurch.
The costs of a 9.0 Cascadia subduction zone megathrust earthquake could reach $75-billion, according to a study for the Insurance Bureau of Canada. The staggering number is more than B.C.’s annual provincial budget.
On Canada’s West Coast, earthquake readiness still isn’t where it needs to be. Being ready comes at a price, but not being ready comes at a far greater one.



Earthquakes & Richmond

 Along the coast of British Columbia, earthquakes are a reality.  Richmond's unique characteristics often raise questions about the potential effects of an earthquake on our community.  Although we have no control over this natural phenomenon, we all have a role to play in preparing for our own safety.

Whether you are a response agency, a municipality, a resident or a business, a little knowledge can go a long way to help minimize the damaging effects of an earthquake.  These sections provide factual information on earthquakes and the best available assessment on how Richmond will respond:
To learn how to protect yourself during an earthquake visit During an Emergency.
Richmond & Earthquakes
Richmond’s Buildings are Expected to Do WellAll new buildings in Richmond are required to meet the BC Building Code.  As early as the 1955 edition, the code has included structural design criteria to mitigate forces from earthquakes.  The objective of the code is to ensure an acceptable level of public safety, which is achieved by designing buildings to prevent major failure and loss of life.  Buildings designed in conformance with these provisions should be able to resist major earthquakes without collapse.

Although this standard is periodically updated as new science and best practices become available, the fact that much of Richmond is of newer construction means buildings are expected to perform well.  If concerned about how a building you own might be affected by an earthquake you will need to contact a Professional Structural Engineer to assess it against the latest BC Building Code. 
Liquefaction May Occur
 During an earthquake, shaking can Earthquake crosswalkcause loosely packed, water-saturated sediments such as sand or silt to turn into a fluid mass.  This is known as liquefaction. When this happens the sediments lose their strength and can no longer fully support structures, which may lean or settle.
Liquefaction can occur during an earthquake depending on the location, size and duration of an earthquake.  Homes and buildings could settle and crack and roads and other surfaces could become uneven due to soil failure.  The best geotechnical information available to date indicates that there are areas that are at risk of liquefaction.  All new structures in Richmond are built on improved ground and use foundation systems such as piles or raft slabs that are specifically designed to eliminate or mitigate liquefaction. We are doing our best.
We're Working to Ensure our Dikes Remain Stable
The City regularly inspects and upgrades its dikes to ensure their structural integrity.  Studies have been completed at key locations to assess dike performance during an earthquake and to plan improvements.  Additionally, dike raising programs make allowances for acceptable settlement during an earthquake.
Richmond is Not at Significant Risk of TsunamisTsunamis are long, high ocean waves commonly generated by underwater earthquakes. The most recognized source of an underwater earthquake that may cause a tsunami capable of reaching the city of Richmond is from the Cascadia Subduction Zone located in the Pacific Ocean to the west of Vancouver Island.  Vancouver Island lies as a kind of breakwater between the Pacific Ocean and Richmond, if a Pacific tsunami was generated it is estimated that waves would dissipate to around 0.5 metres in height as they reach the western shore of the Fraser delta.  The City's dikes would adequately mitigate the effects of this type of event.

To learn more about Tsunamis and how they may impact the city of Richmond visitTsunamis and Richmond.
Richmond’s Unique Situation
Richmond has unique characteristics.  Richmond is renowned for its rich soil and stunning location between the arms of the Fraser River.  These characteristics enhance Richmond's local economy and liveability.  They also present some unique challenges for earthquake emergency planning.
Richmond's soil is made of silt and sand.  This is what makes Richmond a strong agricultural community.  Our soil is ideal for growing cranberries, blueberries and the like; however, the energy caused by an earthquake could take longer to dissipate and the shaking more amplified in these softer soils than it would be on firmer soil and bedrock.  The good news is that these softer soils tend to absorb the damaging high frequency shaking better than areas located on rock.
Richmond is an island.  Being surrounded by water enhances Richmond's liveability.  It also means that Richmond is connected to other communities through a network of bridges.  Seismic upgrades to a number of older bridges have been undertaken in recent years and continue as necessary to enhance their structural integrity.  This will help to alleviate transportation impacts in the event of an earthquake.
Richmond has plans for coping with emergencies. The City of Richmond puts significant resources toward developing, refining and implementing emergency procedures.  Community safety is of paramount importance.  In the event of an earthquake, the City will activate its Emergency Operations Centre to coordinate response efforts.
Earthquake & Preparedness

The Threat of Earthquakes
Earthquake BuildingNo Surprise, Earthquakes are Inevitable in Our Region.
The entire Lower Mainland is located in one of the most seismically active regions of Canada.  Small earthquakes occur almost daily in this area.  More than 100 earthquakes with a magnitude of 5 or greater have occurred in southwestern BC (most offshore) in the past 70 years.  We must be prepared for more earthquakes.
House on TruckThe Earth Moves in not-so Mysterious Ways
Earthquakes occur when the tectonic plates that makes up the earth's outer shell slip past or under one another and release stress.  Imagine the earth's outer crust as resembling cracked eggshells that are in subtle, constant motion.  Earthquakes occur mainly along faults at the edges of the plates as well as along cracks within the plates.  There are no known active faults under Richmond.  All known active faults in our area are located offshore.
All Earthquakes are not Created Equal
There are three different types of earthquakes that can occur in our area: crustal, subcrustal and subduction.
Crustal earthquakes originate in the North American plate (see Fig.1) to depths of approximately 30 kilometres.  These shallow earthquakes account for about 75% of small earthquakes in this region.  In fact, between 200 and 300 of these shallow earthquakes occur in the continental crust of the North American Plate each year.  Of the three major crustal earthquakes that have affected our area in the last 150 years, two occurred on Vancouver Island (in 1918 and 1946, with magnitudes of 7 and 7.3 respectively) and one in Northern Washington State (in 1872, with a magnitude of approximately 7).
EQ DiagramSubcrustal earthquakes are earthquakes that extend to depths of approximately 100 kilometres.  In this area, they take place within the Juan de Fuca Plate that slides beneath the North American Plate.  This is the type of earthquake that occurred just south of Seattle, Washington in February 2001 (magnitude 6.8).  The maximum magnitude for a subcrustal earthquake in our region is 7, primarily because the Juan de Fuca Plate is very thin and only relatively small rupture lengths are created.
Subcrustal earthquakes rarely have aftershocks and are concentrated in two areas within our region: 30 to 40 kilometres below the west coast of Vancouver Island and 50 to 60 kilometres below the Straight of Georgia.  Significant earthquakes of this type occurred in 1949, 1965 and 2001 (as mentioned above) at the south end of Puget Sound.  In addition, a subcrustal earthquake with a magnitude of 5.5 struck beneath Pender Island in 1976.
Subduction earthquakes are the rarest and most damaging types of earthquakes, with magnitudes of 8 or larger.  The threat for our area lies just off the west coast of Vancouver Island where the Juan de Fuca and North American Plates interact.  Pressure may be building at the contact points of these plates.  When this pressure becomes excessive, enormous stress will be released, causing a huge subduction earthquake.  The last such earthquake in this area occurred over three hundred years ago in January of 1700. Subduction earthquakes occur every few centuries.
The Richter Scale
The Richter Scale is a logarithmic measurement of the magnitude of, or the amount of energy released by, an earthquake.  The following table describes the effects of earthquakes of various magnitudes (M):
1-3Recorded on local seismographs, but not generally felt 
3-4Often felt, no damage
5Felt widely, slight damage near epicentre
6Damage to poorly constructed buildings & other structures within 10's km
7"Major" earthquake, serious damage up to approximately 100 km (recent Taiwan, Turkey, Kobe & California earthquakes)
8"Great" earthquake, great destruction & loss of life over several 100 km (San Francisco 1906, Queen Charlotte Island 1949)
9Rare great earthquake, major damage over a large region over 1000 km (Chile 1960, Alaska 1964, and the west coast of BC, Washington, & Oregon 1700) 
Source:  Geological Survey of Canada
Some Significant Earthquakes in our Region
17009.0Vancouver Island
18727.4Washington State
19096.0Gulf Island Region
19187.0Vancouver Island
19467.3Vancouver Island
19497.1Puget Sound
19765.3Pender Island
19904.9Northern Washington
19974.6Strait of Georgia
20016.8Olympia Washington
Source:  Geological Survey of Canada

Earthquake hits off coast of Port Hardy -- felt in Kelowna.

WATCH ABOVE: Shaking was felt across the province, but no damage or injuries were reported after a 6.6 earthquake hit off the coast of Vancouver Island. Global News has full coverage.
VANCOUVER – A 6.6 magnitude earthquake struck off the coast of Port Hardy on Vancouver Island Wednesday night.

According to the United States Geological Survey, (USGS), it struck at 8:10 p.m. PDT and the epicentre was located about 91 km south, off the coast, at a depth of about 11 km. It was originally recorded as a 6.7 but was downgraded to a 6.6 magnitude quake.
Residents in Port Hardy said the ground shook for about 35 to 40 seconds during the preliminary earthquake. Groceries were knocked off the shelves at the local Overwaitea store.
People are saying they felt it as far away as Langley and Kelowna.
Here’s a sample of some of the tweets:
  • Holy earthquake! #kelowna any body else feel that!?
  • I felt the earthquake here in Kelowna. Was on the phone bouncing on my stool, tv and chandelier swinging.
  • Anyone else just feel the earthquake that hit Van Island? Our building in downtown Kelowna was swaying, lights moving! Need wine! 6.7 mag
  • Yep that was a small earthquake you felt #Kelowna My lighting fixtures were swaying!
The National Weather Service says there is no risk of a tsunami.
However, the USGS says to expect aftershocks. Earthquakes Canada reports there have been three aftershocks – magnitude 5.0, 4.2 and 4.2 struck the same region at about 8:20, 8:41 p.m. and 10:16 p.m. PDT respectively. These secondary shockwaves are usually less violent than the main quake but can be strong enough to do additional damage to weakened structures and can occur in the first hours, days, weeks, or even months after the earthquake.
“It [was] right at the boundary where the off-shore Juan de Fuca Plate starts to subduct or go under the edge of the North America Plate.”
“It’s part of the normal seismicity that we’ve been getting,” she added, “since we’ve been monitoring very closely over the past 20 years, 30 years.”
WATCH: Port Hardy earthquake shaking zone:
Pat Quealey from Emergency Management B.C. said everyone reacted as they should have in this situation. He said they are hearing there may be some minor damage, but no significant damage. However, they are checking into reports that a First Nations lodge may have shifted on its foundations during the earthquake.
“In the wider context, we need to be prepared all along the Pacific Rim to respond to seismic threats,” he said. “The really important thing is we can never be too prepared. We need to be prepared all along the Rim of Fire for this risk.”
“It’s a really good reminder to all of us that preparedness starts with local families,” he added. “We live in a volatile area and it’s necessary to be prepared. Through that vigilance and understanding of the risk, we’ll all do well together.”
WATCH: Emergency Management B.C. responds to the earthquake:
Mayor of Port Hardy, Bev Parnham, said she was actually at a reception when the earthquake struck.
“We were just in the process of welcoming the lieutenant-governor to the community, and the earth started to shake and the building started to shake,” she said. “It was up there with one of those ones that you do feel and that you do remember.”
However, everyone remained very cool. “I think by the time we realized what had happened we were all just sort of looking at each other and [said] ‘Oh, that was an earthquake,’” said Parnham.
“We’re not hearing of any reports [of damage]. Our own infrastructure has been checked and things are fine. We haven’t heard any reports from any communities in the North Island. So, we’re not expecting to hear that there is any great deal of damage,” she added.
Emergency services in Port Hardy are on alert, but Parnham said they are always prepared as they live in a seismic area.
Simon Fraser University Geologist Brent Ward said in comparison this was quite a large earthquake. “Very lucky that it’s off the coast and it’s not that close to high population centres,” he said. “Because this is actually bigger than one of the earthquakes that hit Christchurch in New Zealand and that caused extensive damage.”
“This was quite shallow.”
Ward said he is not surprised many people across the Lower Mainland could feel the shaking. “In certain situations where people are living on or on top of thick, soft sediments, the earthquake waves actually become stronger so I would expect that people in Richmond,where they’re on the thick Fraser River sediments, felt the earthquake, whereas someone like me, whose on sort of a bedrock area with thin sediments, I didn’t feel anything.”

Global BC anchor Sophie Lui felt the earthquake in downtown Vancouver. “I was sitting on my couch and I heard my vertical blinds shaking,” she said. “And thought at first that maybe the rain had started, but they kept shaking and I looked back and my chandelier or light fixture was shaking as well. And then I realized that the shaking kept going and kept going and I thought ‘ok I think we’re going through this again.’”
She said she did not feel the building shaking too much, but it did last about 20 to 30 seconds.
“Most people around Vancouver who felt it seemed to be up high in high rises,” she said.
Diane Brennan was visiting her daughter in Sayward on Vancouver Island and said “I just felt the room swaying. I started to just feel dizzy and I was wondering what was going on, and I looked up and the room was just undulating.”

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