Monday, August 23, 2010

Geoblogging the Geoblogosphere

From GSA (Geological Society of America) Connections:

Each month (or thereabouts), the themed geology blog carnival "Accretionary Wedge" invites geoblogger contributions. July's theme, the role of geoblogosphere, generated quite a bit of activity. A synthesis of contributions is hosted on the History of Geology blog site as "Accretionary Wedge #26: The role of the Geosphere" (30 July). The following is a sampling of blog posts on the topic:
I haven't actively sought to be linked into the geoblogosphere, but I guess I belong there.

Sunday, August 15, 2010

World's largest seismically protected building (?)

Not the largest building, or the seismically safest (which would presumably be in an aseismic zone), but I guess this means the most expensively protected building in a seismically active zone.

This seems to have been San Francisco International Airport at one point, protected by 267 huge ball bearings. (I came across this while reading about bearings, because my paleomagnetic spinner magnetometer needed to have its bearings oiled.)

But, according to a more recent article from Wired magazine, the record now goes to the Istanbul Airport.
The world’s largest seismically isolated building, the new international terminal at Istanbul’s Sabiha Gökçen Airport, is now complete and open for business.

Stretching across more than 2 million square feet, the terminal doesn’t sit directly on the soil, but rather on more than 300 isolators, bearings that can move side-to-side during an earthquake. The whole building moves as a single unit, which prevents damage from uneven forces acting on the structure.

“What an isolation system does is that it enables the building to move through large displacements in unison, and in doing that, you absorb earthquake energy,” said Atila Zekioglu, the engineer at the firm Arup, who designed the building.

Earthquakes accelerate buildings laterally, whipping them back and forth. Isolators (see photo below) slow down the motion of the building. In the case of the new terminal, the building will only have to withstand one-fifth of the acceleration that it would have had to without the earthquake proofing.
The company Earthquake Protection Systems was a principal in both projects.

Sunday, August 8, 2010

Love Waves

I've been a bit blog-lazy lately, but I'll see if I can get back in the swing.

The occasional posts by the Berkeley Seismological Laboratory are well researched, written, and composed.  The latest BSL blog post was about surface (aka L) waves, waves that travel near the surface of the earth. Body waves, so-called P and S waves, are push-pull and shear waves that travel through the Earth's interior. The two types of surface waves, Love and Rayleigh waves, are named after physicists A.E.H. Love and Lord Rayleigh, who worked out the theory of their existence. Body waves provide an "x-ray"-type information of the Earth's interior, while surface waves provide models of the Earth's crust.

I heart Love waves.