The 2001 Nisqually Earthquake

Summary

The 2001 Nisqually Earthquake occurred at 10:54 am, local time, on February 28th in an area of Washington state known as Nisqually (an Indian name), 17.6 km NE of Olympia and 52.4 km deep. It registered 6.8, although this was not official until hours after the quake. Prior to that it had been described as anything from 6.8 to 7.0. This was primarily due to the fact that some areas registered much heavier shaking than others and only after averaging all data could an average of 6.8 be assigned. This quake was very close to the location of a 1949 quake which registered 7.1. The 2001 quake was felt as far away as Salt Lake City, Utah but was unmistakable from Portland, OR to Bellingham, WA.

Surprisingly there were no deaths from the earthquake and only three serious injuries (crushing injuries). One occurred when a chimney fell through the roof of a house and onto a man inside. Although damage was widespread, it was especially severe in Olympia and the Pioneer Square district of Seattle. Damage in Olympia can be attributed to the close proximity to the epicenter while Pioneer Square damage is primarily due to the fact that the district is built entirely on fill-dirt which magnifies the motion of earthquakes. As time passes, further damage is discovered and, in some cases, previously known damage has become worse.

The state capital building in Olympia was damaged and has been closed since the earthquake as repairs are effected. It suffered a crack in the dome and damage to support pillars. Current estimates are that it will be three years before it can reopen, if ever. Meanwhile the government continues operation in other buildings. The governor's mansion was also damaged, but the governor and his family were allowed to return to the mansion the next day. The capital building is built entirely of stone, and was built many years ago, hence the severity of the damage.

Other damage in Olympia was concentrated in the downtown area where many brick buildings were cracked or had walls completely crumble into the street.

In Seattle, several buildings in Pioneer Square have been declared unsafe and remain closed. The front part of the Seattle Chocolate Factory building was completely demolished. One building lost the entire south wall of the top floor, which fell on two vehicles in a parking lot next the building, completely crushing them (one was a car and the other was a van). Some of the bricks also fell through the roof of the restaurant next door, destroying the kitchen. Numerous other buildings lost parts of walls and/or roofs and were severely cracked. We saw this building from third-floor level while driving north on the Alaskan Way viaduct, and it looks much more impressive in-person than in pictures. In late May, the brick facades of three buildings partially collapsed. Probably due to earthquake-related damage.

North of downtown Seattle the Magnolia bridge, which is also built on fill dirt, had over one dozen damaged support pillars which are being replaced or repaired. The bridge remains closed. The Alaskan Way viaduct, which runs along the Seattle waterfront, through Pioneer Square, is a two-level highway with a northbound upper level and a southbound lower level. Both levels are above ground-level streets and parking. There are three to four lanes in each direction. The viaduct sustained cracks in support pillars and was closed for hours while crews inspected it. In fact, many bridges were closed in the hours and days after the earthquake. The viaduct was reopened, but as the weeks progressed, it become obvious that the viaduct was more severely damaged than originally thought. Two weeks after the earthquake, some pieces of the viaduct fell onto the streets underneath. Fortunately no one was injured. Then, during the first week of April it was discovered that some earthquake-induced cracks in the supports had significantly widened. The viaduct was immediately closed to traffic while the damage was reassessed. It is now operating in only two-lanes each direction, and with weight restrictions for trucks. Vibrations from traffic are blamed for the widened cracks. The reduced traffic is supposed to prevent further damage until the supports can be repaired or replaced. The viaduct was built long ago, without consideration of earthquakes, and is on fill dirt. A bridge engineer commented that we wouldn't build a bridge like that these days. In June it was discovered that the structure was now leaning three inches.

Some state highways sustained damage as well. In one case it was due to a sink-hole opening in the middle of the roadbed. In other cases, roads built on hillsides are closed due to the fact that the hillsides are now unstable or have significantly fallen away from the road. And there have been cracks in roads everywhere that have required minor repairs.

The earthquake caused a landslide in one area which blocked the Green River, causing it to back-up and flood some homes in one neighborhood. A channel was quickly dug through the landslide to prevent further flooding. The landslide also destroyed two homes.

At Seatac International Airport the control tower was severely damaged. Most of the tower's supports were damaged and all of the windows fell out. A new tower was already in the process of construction, but wasn't scheduled to open for over a year. Planes already on approach landed safely but all other flights were diverted to other regional airports. Unfortunately the only other international airport in the state (King County International Airport) was closed due to large fissures down the length of the runway. The King Country airport is built on alluvial soil (effectively "natural fill dirt"). By the end of the day Seatac was operating at 20% capacity with the air traffic controllers in a temporary, mobile, control "tower". Currently the airport is operating at 80% of normal capacity.

Power was off for hours after the earthquake. For some people it was off all day. Apparently some power stations contain relays which trip during earthquakes so that fallen power lines are not live. The power crews then must verify that there are no fallen lines and manually reset the relays. This process, understandably, takes a while to finish. Nonetheless, I heard no reports of any downed power lines or damaged power poles/towers.

Total estimated damage from the quake is about $2 billion, so far.

The preceding information was gleaned from many sources and I do not guarantee 100% accuracy. Further up-to-date information can be found at http://maximus.ce.washington.edu/~nisqually.

Personal Notes

I was working in my home office, downstairs that morning. Annette had just brought Kian downstairs and left him playing with his toys next to me while she went to pick up the other kids from pre-school. She was in the dining room, above my office, about the leave when it hit.

At first I thought that Annette had dropped some heavy objects on the floor above my head, but when the noise continued unabated, I realized what was happening. I grabbed Kian and headed for the stairwell where there was less stuff to fall on me from above. I remember shouting up to Annette for her to stay away from the aquarium, which is in the dining room.

It lasted about 10 seconds before it started to abate. At that point I thought "that wasn't so bad", at which point the S-waves hit. P-waves are the first (primary) ground motion to spread from the epicenter. I can only characterize them as a severe vibration. Of course when you violently vibrate a house, everything in it rattles and it is very loud. The S-waves are the secondary ground motion and follow the P-waves. These are more akin to a wave motion and the effects are much more breathtaking. Just when I thought the earthquake was about over the S-waves started and shook the house far more severely than before. This went on continuously for about another 15 seconds. I remember thinking "I hope it doesn't get any worse - I'm not sure the house will hold together if it does". The earthquake continued shaking things intermittently for another 20 or 30 seconds after that. Each time that I thought the shaking was over, I'd feel another bump under my feet and see the walls sway in response. Gradually the periods between these bumps increased until 20-30 seconds later it completely ceased.

In the meantime, Annette had dived under the dining room table and watched as large waves of water sloshed out of the aquarium. Based on the water I soaked up from the carpet, I would guess we lost about 2 gallons of water. However, from the level in the tank I would guess about 5 gallons. You have to understand that we have a heavy glass cover over the aquarium, so the water, which was about 2 inches below that had to slosh up with enough force to push the cover up and allow the water to spill. On top of this cover is a 3" high light. I found alot of water on top of this fixture. The water would have had to reach at least six inches above its normal level to be able to do this. Fortunately the aquarium has sprung no leaks.

A great number of things had fallen over, or off of high shelves. All day I kept finding new things on the floor and momentarily wondering what they were doing there. The only damage we had was from one of my grandfather's trophies which fell six feet onto a concrete floor and broke its wooden base. A little Elmer's glue and everything was fine. I have a CD case in the living room. It has about ten shelves for its six foot height. The CDs on the top shelf were sticking half-way out. If they had moved another centimeter out, I would have had a mess of about 100 CDs piled on the floor. The next highest shelf had the CDs sticking out about one quarter of their length. The next shelf had them out only a little bit and the lower shelves looked like normal.

The children at pre-school seemed less concerned about the day's events then did their teachers, but the staff did a good job of having everyone dive under the tables and then quickly evacuated the building when the shaking stopped. None of our kids seemed traumatized by the event. After Sionan got home she climbed up on our bed and stood there, wiggling and saying "I'm having an earthquake!"

The next day our water was milky, most likely from sediment stirred up by the quake. I recall seeing many cracks in roadways that weren't there only a few days earlier and I attribute them to ground movement from the earthquake.

The earthquake was 100 times stronger than the 5.2 that we experienced a few years back, both in absolute terms and also in how it felt. When I consider that an 8.0 earthquake would be ten times worse I am confident that our house would have been damaged. A 9.0 (the "big one" that they say could happen anytime in the next 300 years) would severely damage or destroy it.

One family at church wasn't able to get into their house for over a week since the authorities had closed their entire neighborhood, which was on a hill. They are now able to get into their house, but the road remains closed and they have to park down the road. The road is estimated to be repaired within a year. Another family had already had some foundation problems that caused their family room to sink about 3 inches. The earthquake caused the room to sink an additional 3 inches. Neither of these families had earthquake insurance.

Analysis

The foregoing should illustrate the importance of solid ground, versus fill dirt, in the effects of an earthquake. Almost all of the severe damage, far away from the epicenter was to older structures built on loose (fill) soil. During an earthquake, this kind of soil liquefies and provides no support for structures built on top of it. Most of the damaged buildings were un-reinforced brick structures without earthquake retrofits, often dating back more than 100 years.

Further, the higher up from the ground, the more pronounced the shaking (consider my CD case, for instance). This explains why there was more damage to the upper floors of buildings than to lower floors - not that the lower floors necessarily escaped damage.

To understand how amazing are the lack of deaths and low number of injuries, consider the following. The morning of the earthquake was pleasant, sunny, and relatively warm for the time of year. Although it was well before lunch, there would still have been plenty of foot traffic in the Pioneer Square area. That no one was killed by falling brick is amazing. The winter had been unusually dry so the soil was not saturated with water, as it usually would be. As a consequence there was only one major landslide. We often have landslides during the winter without the help of earthquakes. Consider also that a 6.8 earthquake is considered a fairly major earthquake. It was a deep earthquake so much of the energy was absorbed before it reached the surface. But a recent 6.4 earthquake in Japan (which is better prepared for earthquakes, but has a higher population density) resulted in 2 deaths and numerous injuries. Although it, too, was deep, it was not as deep as the Nisqually earthquake. If the same earthquake had happened along the Seatlte fault (which runs through the middle of downtown) it would have been devastating.

The restaurant whose kitchen was demolished by falling bricks usually has several people in the kitchen at that time of day to prepare for the lunch crowd. For some reason, no one was in the kitchen at that time.

One of the houses destroyed by the landslide was occupied at the time of the earthquake. However, the occupant immediately left the house and avoided injury. Further, if it had been only a few minutes later, their young child would have been playing in the part of the house first hit by the landslide. If the occupant had to grab the child before escaping both would probably now be dead.

Governor Gary Locke's young child was playing in the living room next to the television. Because his mother was standing next to him, she was able to pick him up when the shaking started and saved him from serious injury when the television fell onto the floor right where he had been playing. Had she not been standing there at that time, the story would be different.

Numerous other stories are told about how people avoided injury by not being where they normally would be at the time of the earthquake: track lighting falling onto favorite chairs where normally one would be reading the newspaper, for instance.

One can consider it incredible luck or Divine providence. I don't believe in luck, nor do I find the chances of all the stories being statistically realistic. I believe that God graciously protected all of us in this region. Not because we deserve it, but simply because He is kind.