Featured Research

from universities, journals, and other organizations

Brick Chimneys Can Double As Strong-motion Sensors In Earthquakes

Date:
June 23, 2004
Source:
University Of Washington
Summary:
When the Nisqually earthquake struck western Washington in 2001, brick chimneys in parts of West Seattle and Bremerton were left looking like so much straw after the Big Bad Wolf had gone huffing and puffing through.

A damaged brick chimney, one of hundreds, in West Seattle following the Nisqually earthquake on Feb. 28, 2001.
Credit: Photo courtesy University Of Washington

When the Nisqually earthquake struck western Washington in 2001, brick chimneys in parts of West Seattle and Bremerton were left looking like so much straw after the Big Bad Wolf had gone huffing and puffing through.

Hundreds of brick chimneys at the north end of West Seattle and north of Puget Sound Naval Shipyard in Bremerton were seriously damaged or toppled by the magnitude 6.7 temblor.

New research suggests the main culprit might have been the Seattle fault, even though the earthquake was centered 35 miles farther south, near Olympia, and 35 miles deep. The Seattle fault runs from the Kitsap Peninsula across Puget Sound and through southern Seattle, and continues into eastern King County.

The Seattle fault did not move during the earthquake. However, it appears one of its strands might have acted something like a megaphone, gathering the seismic waves and bending their energy toward the surface directly above, said Derek Booth, a University of Washington research associate professor of Earth and space sciences and of civil and environmental engineering.

Booth is the lead author of a paper examining patterns of damage to unreinforced brick chimneys following the earthquake on Feb. 28, 2001, damage comparable to what resulted from a similar western Washington earthquake in 1965. The paper appears in the June edition of the Bulletin of the Seismological Society of America. Co-authors are Ray Wells and Robert Givler of the U.S. Geological Survey in Menlo Park, Calif.

In the days immediately following the quake, the researchers surveyed 60,000 chimneys, block by block, over about 30 square miles. They identified 1,556 damaged chimneys and noted that damage was heavily clustered in certain areas, particularly at the north end of West Seattle and, to a lesser extent, in Bremerton's residential neighborhoods just north of the naval shipyard.

They noted that the damage did not strongly correspond to the distance from the epicenter or the presence of soft soils, unusual topography or steep slopes.

Besides West Seattle and Bremerton, the researchers also surveyed chimney damage in a number of other Seattle neighborhoods, including Magnolia, Wallingford, Green Lake, Beacon Hill, Madrona and South Park. Damage in these areas was far less pronounced and more sporadic. Even a section of Madrona, the only other survey area atop a Seattle fault strand, didn't have damage similar to West Seattle or Bremerton, but it is unclear why, Booth said.

A network of strong-motion sensors throughout the region has demonstrated that the areas with heavy chimney damage typically endured stronger shaking in the Nisqually quake.

"We already knew what the overall pattern of ground shaking was, and we wanted to see if the chimney data reflected that. It did," Booth said. "What the chimneys also do, however, is provide a much greater spatial resolution than the instruments can. The instruments are separated by a half mile in a few places but more than three miles in other places, and if there are differences in shaking over a short distance the instruments will never pick that up because there just aren't enough of them."

In the case of West Seattle, strong shaking from the Nisqually earthquake was detected by a strong-motion detector at a fire station toward the north end of the neighborhood but much weaker shaking was recorded at a school about 1.5 miles farther south. The sensor data did not tell precisely where in between the intense shaking ceased, but the chimneys indicated the drop-off seemed to have occurred around Southwest Charlestown Street, about midway between the two sensors.

Booth noted that the evidence for the Seattle fault's role in the strong ground shaking is still only circumstantial, but he added that the new research supports what has been suggested by previous studies from other areas of the country.

"West Seattle clearly has the strongest damage gradient. It's pretty strong in Bremerton too, but the maximum damage there wasn't as great," he said.

"We believe they are genuinely reflecting differences in the strength of shaking and not the sudden replacement of good chimney contractors with bad contractors, or the sudden replacement of good mortar with bad mortar," he said.


Story Source:

The above story is based on materials provided by University Of Washington. Note: Materials may be edited for content and length.


Cite This Page:

University Of Washington. "Brick Chimneys Can Double As Strong-motion Sensors In Earthquakes." ScienceDaily. ScienceDaily, 23 June 2004. <www.sciencedaily.com/releases/2004/06/040623083616.htm>.
University Of Washington. (2004, June 23). Brick Chimneys Can Double As Strong-motion Sensors In Earthquakes. ScienceDaily. Retrieved September 2, 2014 from www.sciencedaily.com/releases/2004/06/040623083616.htm
University Of Washington. "Brick Chimneys Can Double As Strong-motion Sensors In Earthquakes." ScienceDaily. www.sciencedaily.com/releases/2004/06/040623083616.htm (accessed September 2, 2014).

Share This




More Earth & Climate News

Tuesday, September 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Thousands of Fish Dead in Mexico Lake

Raw: Thousands of Fish Dead in Mexico Lake

AP (Sep. 2, 2014) — Over 53 tons of rotting fish have been removed from Lake Cajititlan in western Jalisco state. Authorities say that the thousands of fish did not die of natural causes. (Sep. 2) Video provided by AP
Powered by NewsLook.com
Raw: Iceland Volcano Spewing Smoke

Raw: Iceland Volcano Spewing Smoke

AP (Sep. 2, 2014) — The alert warning for the area surrounding Iceland's Bardarbunga volcano was kept at orange on Tuesday, indicating increased unrest with greater potential for an eruption. Smoke is spewing from the volcano, and lava is spouting nearby. (Sept. 2) Video provided by AP
Powered by NewsLook.com
U.N. Says Ebola Travel Restrictions Will Cause Food Shortage

U.N. Says Ebola Travel Restrictions Will Cause Food Shortage

Newsy (Sep. 2, 2014) — The U.N. says the problem is two-fold — quarantine zones and travel restrictions are limiting the movement of both people and food. Video provided by Newsy
Powered by NewsLook.com
Sharks Off the Menu and on the Tourist Trail in Palau

Sharks Off the Menu and on the Tourist Trail in Palau

AFP (Sep. 2, 2014) — Tourists in Palau clamour to dive with sharks thanks to a pioneering conservation initiative -- as the island nation plans to completely ban commercial fishing in its vast ocean territory. 01:15 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins