Comparing Portland’s quake risk to that of d...

Published: Wednesday, February 23, 2011, 9:02 PM Updated: Friday, March 09, 2012, 6:25 PM
Joe Rojas-Burke, The Oregonian By Joe Rojas-Burke, The Oregonian
http://www.oregonlive.com/environment/index.ssf/2011/02/comparing_portlands_quake_risk.html

The earthquake in Christchurch, New Zealand rated only a magnitude 6.3 and yet killed at least 92 people and collapsed modern, seismically reinforced buildings because it erupted at shallow depth near the center of a city. Portland sits on shallow faults capable of similar destruction.

“The same characteristics that caused such destruction and so many deaths in Christchurch are similar to those facing Portland, Seattle, parts of the Bay Area and many other West Coast cities and towns,” says Robert Yeats, a professor emeritus of geology at Oregon State University. He asserts that the region needs to pay more attention to the many shallow faults hiding beneath population centers.

Disaster preparedness in Oregon has largely focused on a different kind of earthquakes: those from the collision of massive sections of the earth’s crust, called tectonic plates. From Northern California to British Columbia, an ocean-spanning slab called the Juan de Fuca Plate is plunging beneath the North American plate. In a complete rupture across this Cascadia subduction zone, geologists expect magnitude-9 ground-shaking to persist for several minutes across much of Oregon and Washington. They rupture about once every 450 years.

Most shallow crustal faults are far smaller than subduction zone faults — and haven’t gotten the attention. Shallow earthquakes erupt when one section of Earth’s crust slides past another to relieve pent up forces. Ground shaking lasts for seconds rather than minutes, and strikes in a smaller area than a subduction quake.

Geologists have located three shallow faults that cut beneath the most populated parts of Portland. The largest, the Portland Hills Fault, may pose the greatest risk. It stretches from Oregon City to Scappoose. Corvallis and Seattle also straddle active crustal faults.

Ian Madin, chief scientist with the Oregon Department of Geology and Mineral industries, has studied the Portland faults and says it’s hard to rate the hazard because they have never ruptured in historical time. Evidence in disturbed sediment layers reveals one or two strong earthquakes on Portland Hills Fault in the last 15,000 years. The next one, however, could happen tomorrow.

“All the evidence suggests our local faults have earthquakes very infrequently,” Madin says. “But because the faults are right underneath downtown Portland, if they move it’s going to shake very hard.”

Another risk factor Portland shares with Christchurch is its extensive development on water-saturated sediment along rivers. That kind of ground tends to lose stability during an earthquake and behave almost like a liquid, causing sturdy foundations to sink, tilt and collapse.

That puts a lot of critical infrastructure at risk, says Yumei Wang, a geotechnical engineer with the Oregon Department of Geology and Mineral Industries. Fuel pipelines, petroleum storage tanks, ports and electrical transmission lines are built on ground that will turn to Jell-O in an earthquake.

The strength of buildings may be the most decisive factor in how well a city survives an earthquake. Yeats says New Zealand has some of the most progressive building codes in the world and is better prepared for earthquakes than most U.S. cities. Schools in Christchurch appear to have stood up well.

Many Oregon schools would not. More than half are at a high risk of collapse from a quake, according to a 2007 report by the Oregon Department of Geology and Mineral Industries. Oregon recently awarded $15 million to help two dozen schools and emergency facilities strengthen buildings. State law requires all public safety buildings be upgraded by 2022 and public schools by 2032.

“Up until the 1980s, conventional wisdom held that we were not in highly seismic region,” says Scott Ashford, head of the school of civil and construction engineering at Oregon State University. As a result, he says. “We have an incredible amount of legacy systems, 100-year old water lines, and most of our bridges, built before modern seismic design came around.”

While planning for a subduction zone quake prepares cities for more localized crustal earthquakes, Yeats says additional steps are worth taking. Oregon and Washington urgently need to more carefully identify hidden faults and figure out how much risk they pose, he says.

One model, he says, is California’s longstanding Alquist-Priolo Earthquake Fault Zoning Act. It began detailed mapping of fault zones in the 1970s and prohibited new construction of houses within the zones unless geological studies show that the fault poses a minimal hazard to the proposed building.

“We need more due diligence to be sure that new developments are safe,” Yeats says.

How Would Portland Fare In An Earthquake?

http://news.opb.org/article/how-would-portland-fare-earthquake/

OPB News Kristian Foden-Vencil | April 18, 2012 9:36 p.m. | Updated: April 19, 2012 9:05 a.m. | Portland, OR
Earthquake experts gave a tour of four places within the City of Portland Wednesday to explain what would happen to some retrofitted structures in the event of a magnitude nine Cascadia Subduction Zone earthquake.

The tour included an old brick office block, a bridge, the harbor wall, and a fire station and was organized by the Portland Bureau of Emergency Management.

Mayor Sam Adams says the aim was to raise awareness of earthquakes and promote preparedness.

“Our tour today is intended to be both eye-opening and reassuring,” said Adams.

Eye-opening in that it highlights what the dangers are. And reassuring because the tour included structures that have already undergone seismic upgrades.

The first stop was Skidmore fountain in front of MercyCorps’ new office building.

Like about 1200 unreinforced masonry buildings in Portland, this one was built more than 100 years ago — out of bricks. In a large earthquake, such buildings could well collapse.

Randall Toma, an engineer with ABHT Structural, says that’s why MercyCorps retrofitted the building, with concrete walls and metal beams.

“In some cases the concrete walls encased interior unreinforced masonry walls. In other cases it was placed against the walls. Also we added steel beams and steel columns. It decreased the chance for localized bricks to essentially fall off the building or inside the building,” says Toma.

Toma says the retrofit means people in the building would survive. But it might not be safe afterwards — because of aftershocks.

And aftershocks from a massive Cascadia Subduction Zone earthquake could be substantial.

The subduction zone is a massive fault that runs along the West Coast.

Geologists believe it produces some of the largest earthquakes possible. They say it shakes once every 300 to 600 years and the last one was just over 300 years ago.

The next stop on the tour was Burnside Bridge.

Multnomah County, the City of Portland and the state have identified the bridge as a key crossing point over the river. So it’s had a partial seismic upgrade.

Multnomah County engineer, Jon Henrichsen, says the upgrade basically stops the bridge decks from sliding off the bridge columns.

“During an earthquake this could be vibrated so hard that the portion of the bridge that’s on the expansion side, could fall off its seats and then come down, crushing whatever’s underneath it. So the phase one upgrades put these tubes, if you look up — that tube allows the expansion and contraction to happen, but it has a retainer ring on it that prevents it from pulling off the bridge in the event that it’s shaken,” says Henrichsen.

The county is looking at another upgrade to the bridge that would stop its columns from crumbling. With this improvement, the hope is that the bridge would not only remain standing during an earthquake, but it could also be used afterwards.

The third structure on the tour was the harbor wall, on which there’s been no seismic study.

City of Portland engineer David O’Longaigh concedes it’s not the most important part of Portland’s infrastructure.

“It’s a remnant of the 1930′s when shipping was more important and the port itself was more important. Now it’s really a recreational asset. It holds up the park and for recreational shipping… So from that regard it’s an important asset when it comes to the mental well being of the city.”

The final stop was the central city’s fire station. As an essential emergency services building, it’s been extensively retrofitted — so it will not only survive an earthquake, but function properly afterwards.

Engineer Devon Lumbard says even though the first station was built in the 50′s, it still needed a lot of work.

“Those deficiencies included the doors on the very front of the fire station could jam closed during an earthquake. So the very first thing the fire fighters would have to do would be to cut their way out of the building before they would be able to help anybody,” says Lumbard. Those problems have now been fixed.

But while Adams and others point to such improvements as evidence progress is being made, the truth is that Portland would suffer terrible damage in the large earthquake.

Yumei Wang of the Oregon Department of Geology and Mineral Industries points to Christchurch in New Zealand as an example of what could happen here. A 6.3 magnitude earthquake struck Christchurch last year. Like Portland, it stands on land that’s susceptible to liquefaction, the process by which shaking soil acts like a liquid.

“About half of downtown Portland has potentially liquifiable soils. In Christchurch their central business district was closed for five months and they’ll never have a full recovery. The area looks like a ghost town,” says Wang.

Geologists estimate there’s a 10% chance of a magnitude 9 earthquake in Portland over the next 50 years — and a 37 percent chance of a magnitude 8 or less.

FEMA National Flood Safety Awareness Week Coming U...

This Citizen Corps News Digest is provided by FEMA’s Individual & Community Preparedness Division to highlight community preparedness, resilience resources and activities recently announced by federal agencies and Citizen Corps partners.

Preparedness Tip of the Week:

Next week marks the beginning of National Flood Safety Awareness Week (March 12 – March 16)! Find out what you can do to prepare yourself and your community in the event of a flooding incident in your town by learning more about the important tools and resources that FEMA offers which you may utilize before, during and after a flood.

Citizen Corps Partners and Affiliates Updates

March FEMA Monthly Preparedness Update

Tuesday, March 13th

3:00 p.m. ET (2:00 CT/1:00 MT/Noon PT)

Register HERE if this is your first time joining a webinar in the Community Preparedness Webinar Series.

Log in HERE if you have already registered for this webinar, have registered for a previous webinar, or if you’re a HSIN.gov user.

Overview

Join us for this FREE event as we address the preparedness and readiness needs and interests of our state and local partners.

This month’s call will feature:

How to Engage Faith-Based Organizations in Your Community in Emergency Management:

David L. Maack of Racine County, Wisconsin Emergency Management will discuss engaging faith-based organizations in planning and recovery.
Sherry Capers, of Miami-Dade County Emergency Management will discuss capacity building with faith-based organizations and meeting the needs of those that serve diverse and hard-to-reach populations.

Get Ready for National Preparedness Month 2012: The Ready Campaign will discuss plans for the next National Preparedness Month in September.

NOTE: Before participating on the call, you must register for the event. If you’ve already registered with the Community Preparedness Webinar Series please use this link to log in on the day of the webinar. If you have any questions regarding the call, please contact ready@fema.gov .

Hearing the Japanese Earthquake – 2 clips

This recording of the 2011 Japanese earthquake was taken near the coastline of Japan between Fukushima Daiichi (the nuclear reactor site) and Tokyo. The initial blast of sound is the 9.0 mainshock. As the earth’s plates slipped dozens of meters into new positions, aftershocks occurred. They are indicated by “pop” noises immediately following the mainshock sound. These plate adjustments will likely continue for years.

and

In this recording of the 2011 Japanese earthquake, taken from measurements in California, the quake created subtle movements deep in the San Andreas Fault. The initial noise, which sounds like distant thunder, corresponds with the Japanese mainshock. Afterwards, a continuous high-pitch sound, similar to rainfall that turns on and off, represents induced tremor activity at the fault. This animation not only help scientists explain the concept of distant triggering to general audiences, but also provides a useful tool for researchers to better identify and understand such seismic signals in other regions.

Georgia Tech Associate Professor Zhigang Peng has converted the seismic waves from last year’s earthquakes into audio files. The results allow experts and general audiences to “hear” what the quake sounded like as it moved through the earth and around the globe.

Officials work to get people ready for disaster~ A...

The Portland Observer
– March 7, 2012
http://portlandobserver.com/?p=11629

Officials work to get people ready for disaster
By Mindy Cooper/ The Portland Observer

In an effort to alleviate both the fear and stigma surrounding earthquakes and tsunamis, emergency management officials are on a mission to inform the public about how to be prepared after a natural disaster.

The fear of natural disasters is often perpetuated by a lack of information, according to Dr. Althea Rizzo, geological hazards specialist with the Oregon Management Office.

To help prepare residents to be practically ready to face the aftermath of a major earthquake or tsunami, the state office and various agency experts are stepping up to provide free preparedness workshops to inform the public.

Rizzo recounts the story of an eighth grade girl who saved hundreds during the 2004 tsunami in Thailand because of her lesson in geography.

Tilly Smith, an eighth grade student on holiday with her family from the United Kingdom, had just taken a geography class where she learned about earthquakes and tsunamis, before she saw the tide rush out in Phuket, Thailand seven-years ago.

“Because she had just studied this in school, she was able to evacuate the beach and save about 250 people’s lives,” said Rizzo. “You don’t have to live on the coast to make the information useful.”

Throughout the past several years, Oregon has suffered considerable damage from winter storms and last year’s tsunami off the coast of Japan.

“Scientific evidence indicates that Oregon is at risk for much larger and potentially more damaging tsunami created by an earthquake associated with the Cascade Subduction zone,” said Rizzo.

Once individuals become informed, they can prepare, she said, which helps families take the action they need to ensure they will be safe after a tsunami or earthquake.

In the past two weeks, Oregon has experienced 10 to 12 earthquakes, said Rizzo. “This is about average,” she said. “Oregon is very seismically active.”

Just last month, Rizzo said an earthquake with a magnitude of 6.0 occurred merely 15 miles off of the coast. “That was pretty big, but luckily, it was far enough off shore that it was felt by only a few,” she said.

Rizzo said, however, it was the same size of earthquake as the Spring Break earthquake, which went underneath Scott Mills in 1993 and caused the Capital building to crumble in Salem.

“A misconception is that most buildings are built to a seismic standard, and that they won’t fall down,” she said. “But it might not be usable afterwards, and a lot of our building stock will need to be demolished unless people take action beforehand.”

Although we are the only state that has programs and grants towards schools and critical facilities for seismic and retro-fitting, Rizzo said there is still an issue of funding to make sure local municipalities have taken proper preventative action.

Rizzo explained a lot of her time is spent educating the public and policy makers about the seismic hazard present throughout the state.

Oregon’s biggest danger from earthquakes come from the Cascadia Subduction zone, which runs from northern California to British Colombia, and it is about 100 to 150 miles off of our coast, she said. “It is capable of producing the largest earthquakes in the world.”

Although the Spring Break earthquake was the last time there was a major earthquake in Oregon, she said the longer the quake builds, the more stress and impact the next quake with have. She added the last Cascadia subduction zone earthquake was in 1700.

And this is why it is good to be both informed and prepared, she said.

According to Rizzo, it is very possible that in some parts of the state, depending on where you are, your family could be isolated for anywhere up to three weeks. “People tend to focus on the tsunami, but they forget the earthquake itself will impact a lot more people here in the Pacific Northwest,” she said.

“By being prepared you can make sure your family has the food, water and medication they need until help can get to you.”

People can do things to be ready, even for something as scary as an earthquake, she said. “Think about how much more relaxed you will be if you go ahead and get three weeks of water. Then you’re set, and you don’t have to worry about it.”

She said even in Japan, which is considered the most seismically prepared country in the world, it took two weeks to get to some families. “Last year’s earthquake and tsunami in Japan brings the hazard home and offers a teachable moment,” she said.

“You need to know where safety is,” she said. “The reason why I do tsunami education inland and in the valley is because we all go to the beach. Even if you are from Portland you need to know about tsunami safety.”

A series of free workshops will be held from March 8-26 in various locations throughout the state to help inform the public on earthquake preparedness.

The workshops, which run between an hour and two hours, will cover different topics from tsunami science to tsunami safety, she said. “We also talk a bit about earthquakes because they cause tsunamis.”

After the workshops, residents will be more prepared and ready to recognize a natural disaster, plan evacuation routes, know amounts of water and food necessary for survival, and recognize issues surrounding a power shortage. “Think about how much more relaxed you will be if you go about and get three weeks of water. Then you’re set. You don’t have to worry about it,” she said. “And don’t forget your pets!”

I hope for a prepared population that will be able to recover quickly after an earthquake or tsunami, said Rizzo. “Come out and learn something about them.”

For more information about how to attend, or to contact the Oregon Management office, visit the website oem-oregon.blogspot.com or call 503-750-8308.