Feb 27, 2011
By Vince Stricherz
News and Information
Nisqually Earthquake – Quick Facts
Date: Feb. 28, 2001
Epicenter: Anderson Island, about 10 miles from Olympia
Depth: 53 kilometers, or about 32 miles
Damage: Estimates from $500 million to more than $2 billion
Deaths: One indirectly attributed to the earthquake.
Structures with significant damage: Alaskan Way Viaduct and Magnolia Bridge, Seattle; the Washington State Capitol and the Fourth Street Bridge, Olympia; control tower, Seattle-Tacoma International Airport; unreinforced masonry or concrete buildings in the Pioneer Square and Sodo neighborhoods of Seattle.
In the decade since the Nisqually earthquake shook buildings, rattled nerves and rolled the ground in Western Washington, the level of seismic danger in the Pacific Northwest hasn’t changed. But scientific ideas about the danger have evolved and the ability to study and prepare for it has improved immensely.
Scientists from the University of Washington and the U.S. Geological Survey have increased their knowledge about the three different types of non-volcanic earthquakes that occur in the Northwest, and are learning how unfelt “episodic tremor and slip” events relate to seismic risk. The number of seismic sensors and the territory they monitor has tripled. Engineering standards have improved to meet the region’s seismic risks.
“Most places in the world that experience earthquakes have a better recorded history than we have, so we’re at somewhat of a disadvantage,” said Stephen Malone, a UW emeritus research professor of Earth and space sciences.
Malone was director of the Pacific Northwest Seismic Network, based at UW, when the magnitude 6.8 Nisqually quake struck just before 11 a.m. PST on Ash Wednesday, Feb. 28, 2001. Similar to quakes centered near Olympia in 1949 and Tacoma in 1965, the Nisqually quake was about 32 miles deep, near the interface where the Juan de Fuca tectonic plate is descending beneath the North American plate.
These intraslab quakes have been the most common damaging earthquakes in Western Washington’s recorded history, but the time frame in which they recur is probably the least understood, said John Vidale, a UW Earth and space sciences professor and current director of the seismic network.
“They are not regular. There is no reason to believe another one is overdue to happen,” Vidale said, though he added that if history is any guide Western Washington is unlikely to be as seismically quiet as it has been for the last five years.
The geological survey estimates there is a better-than-80 percent chance of an intraslab earthquake of magnitude 6.5 or greater in this region within the next 50 years.
Intraslab quakes are not the most-damaging seismic events in the region. Shallow quakes on crustal faults – such as the Seattle, Tacoma and South Whidbey Island faults – don’t happen nearly as often but can cause more significant damage near their source and also could generate tsunamis in Puget Sound. The last major quake on the Seattle fault, estimated at magnitude 7.4, happened about 1,100 years ago, raising the south end of Bainbridge Island and what is now Alki Beach in West Seattle 15 to 20 feet and generating a Puget Sound tsunami.
Then there are megathrust, or subduction zone, quakes that mostly occur off the Washington and Oregon coast and could be almost as powerful as the magnitude 9.1 quake that struck south Asia in 2004 and generated a deadly tsunami. As the Juan de Fuca plate slides beneath the North American plate, a process called subduction, the plates are locked together near the surface and stress continues to build up over centuries. When the locked zone gives way, a mammoth earthquake results.
The last subduction earthquake here, in January 1700, generated a tsunami that did damage in Japan and affected the entire Pacific Basin. Such a quake could be less damaging than, say, one on the Seattle fault, since it would be farther away from the population centers of Western Washington. But the prolonged shaking, perhaps five to nine minutes, would still cause significant damage throughout the entire Pacific Northwest west of the Cascade Range.
Scientists know these magnitude 9 earthquakes in the Cascadia subduction zone occur on average every 500 years, though they can happen on shorter or longer time scales. Vidale estimates the danger now is about half what it will be in 200 years. “The risk is not as high as it’s going to get, if the models are correct,” he said.
The Nisqually earthquake was recorded on the first modern strong-motion sensors deployed in Western Washington. Since 2001, the coverage has tripled to more than 130 stations, and 30 more are in the works. A new array of sensors has been deployed to record liquefaction, which occurs when the shaking pushes ground water to the surface to liquefy the soil. There are few detailed liquefaction records in the United States, and some came from the Nisqually quake.
Other developments since the 2001 quake include:
“We’re more evenly monitoring the Pacific Northwest, including parts of eastern Oregon and eastern Washington that weren’t monitored before,” Malone said. “We also have better monitoring of the Cascades volcanoes.”
Scientists here and around the world are trying to devise methods to predict earthquakes, “but right now we can’t even see how that might work,” Vidale said. In addition, there are hopes for refined forecasting ability, based on historic patterns and general probability, he said.
It also is possible now to develop an early warning system, using data from sensors close to an earthquake source to determine which direction the waves will go and how strong the shaking might be. Such systems are already being used in Japan, Mexico and elsewhere.
“That could give people advance warning ranging from a few seconds to a few minutes,” Vidale said. “The question is whether it is worth the financial cost.”
Mary Ellen and I are both extremely pleased with the work that Matt and Richard did. Please pass on my personal "thank you" to each of them.
We were pleased with the amount of clean-up that was done at the end of each day.
Even with your discovery of unforeseen conditions that necessitated additional framing, it was still done within a very reasonable time-frame. My overall experience with Sound Seismic has been very positive and we will recommend your services to our circle of friends and family.
Again, thank you for a very "enjoyable" experience!
Mark and Mary Ellen Whitesell, Ballard, Seattle
I wish to praise SOUND SEISMIC for the earthquake retrofit they completed on my home. From the estimate to the finished job, Leif and his crew were professional, hard working, pleasant and exceptionally CLEAN. They handled the permit and inspections seamlessly. Office support from Elizabeth was equally professional, reliable and fast. I can't describe everything so I'll just say the whole experience was great.
Kristin Hill, Wallingford, Seattle
We recently had Sound Seismic do our earthquake retrofit. I cannot compliment enough the very professional job they did. Leif Jackson, the owner, sat with us for two hours answering questions and explaining how earthquakes work. He was completely above board, not promising more than he could deliver. He left interesting reading material so that we could evaluate and decide for ourselves. The most compelling was from FEMA warning people in the Puget Sound area to do everything they could to protect their homes because of our earthquake risk.
Once we were in contract, Leif sent our information to a structural engineer who drew up the plans. The bid was fair and complete. The crew showed up on the date the job started and completely it quickly. It looks great. Our new pony walls are gorgeous and the bolts and clamps very reassuring. City inspections were completed for the bolting and then for the finished job. This company is certified and high quality. Our house will be sticking around on the foundation. I encourage you to get over gambling about retrofitting and hire these guys. They are great.
Emily Elliott, Queen Anne
The crew kept me informed of their progress and plans all the time. They told me what their plans were, and delivered every time. Very satisfying knowing I could count on them doing what they promised - when they promised it!
Martin Muller, Olympic Manor, Seattle
Sound Seismic was the most professional group of contractors/employees I have ever dealt with. They were knowledgable, dependable, and skilled. The project lead was obviously well trained and knew what he was doing, was able to effectively manage and direct his crew and subcontractors. A quality job. Discovered an area behind my walls were my house was not up to code. Worked well will me to correct the problem and professional and reasonable about the change order.
Grateful homeowner, Mercer Island
The Sound Seismic crew arrived on time and got started on this structurally engineered and contracted job. It was estimated to take approximately one week to complete this work. The job was completed in 4 days with great professionalism and dedication to the work completed. The work passed a city inspection with no additional work required. The quality of work is excellent with great attention to detail.
Leon Young, Issaquah
Based in Ballard, the 2 man crew of Sound Seismic did a very clean, professional job of installing the earthquake retrofit. I was very happy with quality of the work and the way the crew kept the site clean and organized every day. They stick to a firm 8-hour work day for their employees and offer health benefits, a rarity in the contract world, it would seem. So their bid was not the lowest, however was comparable to a number of other firms, within 5-10%. Very punctual and professional in all coordination and in handling the 2 inspections reqd. by the city. No surprises or additional costs. I would recommend this contractor overall.
Jennifer Dovey, Broadview, Seattle
Sound Seismic did such a thorough job. Looking at their work lets me sleep better at night knowing my house is now very unlikely to shift off its foundations in an earthquake.
P. Kiraly, Madrona, Seattle
We thank you for the very professional work done by all of your people that we have had contact with. The crew working here were outstanding, and we were charmed by your lead carpenter, Matt.
Our basement has not been this clean in 70 years (the house is 70 years old)!
Bryant neighborhood, Seattle
We had a wonderful experience with Sound Seismic. After the devastating earthquake in Japan my husband and I were quite worried about our 3 story brick home and decided to retrofit our basement as a way to ease our anxiety and protect our family.
Sound Seismic's estimate was more reasonable than any of the others we got and we felt very confident knowing that Leif and his team have done many retrofits, including our friend's basement. Leif was able to explain the process to me, answer my questions, and gave me the estimate within an hour of coming to the house.
The hardest part of the process was moving our furniture and boxes out of the way to prepare the basement - after that things just moved along smoothly. I had been expecting huge holes in the walls and dust everywhere but the work was really tidy and not nearly as disruptive as I had feared. My kids and I were able to stay in the house the whole time, only playing out in the backyard a couple times when the banging was loud. The baby was even able to take naps in the midst of the demolition!
Matt was very professional and friendly, he always arrived on time and he communicated well, checking in with us at the end of each day to show us the progress of the work. He was able to finish the work a half-day sooner than planned and there were no hidden costs or extra changes when the invoice arrived.
I would highly recommend Sound Seismic to anyone -- they were fantastic!
Rachel Opel, Ballard, Seattle
Thanks for the great work on the house - you've done an outstanding job of prompt, low-impact work - and leaving the job site in excellent shape. Appreciate the attention to detail."
Wayne Dodge, Ravenna, Seattle
"I wanted to follow up and thank you for your good communication, strong planning and flexibility.
Matt was great. Very professional, low key, friendly and efficient."
Urs Koenig, Madrona, Seattle
Sound Seismic gave a very competitive bid, clearly explained everything they were going to do, accomodated my schedule, and produced a very high quality outcome. I highly recommend them.
Gary Johnson, Wallingford, Seattle
Matt and Richard did a great job! It was a pleasure to meet them. And as soon as I met Matt, I knew that everything would be done 'right.'
They took extra care at every level: and left everything better than ever. They were able to remove the siding without cutting it, which is great, too.
I am glad that I got to see how substantial the anchors, fasteners, etc. are - and how robustly the plywood panels are nailed in. ( It was hard for me to tell from the blueprints alone.)
I am very happy with all aspects of the plan and the work, Leif.
David Rosenbaum, Sand Point, Seattle
All in all, we felt the project went extremely well. Given the number of earthquakes worldwide of late, we are pleased to have had the work done. We’d rather not have it tested, but we know we are in as good a position as possible if the ground starts shaking!
I wanted to let you know what a great job that your crew did on our earthquake retrofit. They were very knowledgeable about the whole process and answered any questions we had without hesitation. Their work was excellent and they finished the job quickly. I have done my share of remodeling in the past and I can say that they cleaned up after each day’s work more thoroughly than anyone I’ve ever encountered. They took obvious pride in the retrofit work they did but also in the cleanup. They saw that as an integral part of the Sound Seismic service. All in all, it was a fast and painless experience.
Thanks for assigning those fine young men to our job.
Paul Gustie, Fremont
Sound Seismic performed an engineered retrofit on our house built in 1928. I've never had a better experience working with a contractor - thoroughly professional (truly experienced and knowledgeable in their craft), they were also excellent communicators throughout the engagement. And the cleanup afterwards was amazing. I would recommend them without reservation!
George Murphy, Northgate, Seattle
I wanted to thank you for the wonderful job you did retrofitting my home in South Seattle. I was aware that it would be a challenge and it proved to offer more problems than we expected. You met them all and did a great job correcting the rot and damage that happened over the years since 1927, when the house was built.
When I arrived home yesterday the basement was clean and organized. It was the first time I did not have to spend hours cleaning up after a contractor. Your lead carpenter and his assistant were a great team. Thanks for all your efforts.
Patrick Murphy, Mount Baker
I can't think of a single way you could improve the service of your company. Yours is one of the VERY best companies I've worked with on this home.
Jeannie Macri, West Seattle
Sound Seismic completed a earthquake retrofit on our house. Their explanation about what to expect and what we'd get was clear and straightforward; the work was completed as described, as scheduled and exactly on time; clean-up: spotless.
Harriet B., Ballard
"The experience with Sound Seismic was possibly the finest I have had in my dealings with any of my trade contractors. Your crew was knowledgable, well informed, hard working, tidy, as well as a pleasure to have on my job."
Thank you very much for your excellent work on retrofitting our house. We appreciated your careful oversight of the project, ongoing contact with the engineering firm, attention to detail, and clean and timely work. You really rose to the challenges presented by "this old house."
Sound Seismic exhibited a great combination of skill, hard work, and professionalism. You treated our home and our project as though you were doing it on your own house.
Everything looks good. Thanks for the all the work your guys did, very professional.
Stuart Jamieson, Montlake
Sound Seismic did an excellent job of the seismic retrofit on my two-story house, which entailed quite a lot of siding work as I don't have a basement. The workmen were punctual, neat and meticulous. I feel safer because of their work.
Pippa Kiraly., Madrona
Just wanted to send you a note to express how pleased we are with the work your firm recently completed. You did exactly what you said you would and the quality of the work is first rate. Also, please tell Matt how much we enjoyed him. Thanks,
Gary Johnson, Wallingford