Building Shaker Quake Machine

Earthquake. This kind of geological pehnomenon has been of most recent natural-disasters. When an earthquake hits, it can destroys any infrastructure human built, including building. That is why research and new method of construction develop to aim the earthquake-proof building. And also the method of planning, simulations, and many more.

One of the most important inventions is Building Shaker Quake Machine, a shaker machine created by "placing a building in" and "shake" it to simulate the earthquake.

How will a tall building react to earthquake-like stresses? Computer modeling has helped until now. Before it apllied to the real test on the field, the simulation performs by a computer modelling. Next image is the screenshot of the computer modelling.

The simulations show how the specific parts of the building are moving. Comparing the real-world data with the computer model helps them improve their model; this improves the accuracy of the model when simulating the effects of stronger quakes.

The powerful computer models that show a 275-tonne building being shaken to its foundations in unprecedented detail could help engineers better protect structures against earthquakes.

Engineers at the University of California in San Diego, US, have been using a giant "shake table" to reveal the affect of a 6.7 magnitude earthquake on a seven-storeys structure.

However, there is nothing like a good, real-world test. Engineers from the San Diego Supercomputer Center have combined the best of both worlds by putting up a full-size 275 ton building on a shake table.

Not just any shake table - the world's largest outdoor Large High Performance (LHP) shake table developed for the Network for Earthquake Engineering Simulation (NEES) project.

The building was equipped with hundreds of sensors to yield precision data on how the building flexed during simulated quakes. It turned out that listening to audio and sensor data provided the key to comparing the film footage of the real building, and the pictures of the simulated building structure.

"By recreating the shake table experiment in movies in a virtual environment based on the observed data, this lets engineers explore all the way from viewing the 'big picture' of the entire building from a 360-degree viewpoint to zooming in close to see what happened to a specific support," said SDSC visualization scientist Amit Chourasia. "Integrating these disparate data elements into a visual model can lead to critical new insights."

sources :
http://www.technovelgy.com
http://starspirit.stumbleupon.com

Geological changes

When we talk about the geological changes, it always in the geological-time-scale, they mean the change happens over the course of millions of years. Grand Canyon is one of the examples, where the Colorado River gradually cuts through the soft rock of the Colorado Plateau until it has made a 4,000-foot deep chasm. Most of the time, and most of the geological phenomenons, change is slow.

But sometimes, in some spesific and unusual conditions, geologic change happens all at once. This was what happen on Ranongga Island in the Solomon islands after the strong earthquake followed by the tsunami. The huge quake pushed much of the island up, raising the coral reefs that ringed the island above the water. In the course of a few minutes, Ranongga Island acquired several meters of new beach.

From the image belows, image acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), we all can see the changes.
When ASTER took the 2007 image, the tide was 29.4 centimeters higher than it was when the 2006 image was taken, and yet the uplift is still visible. The lush vegetation that covers the tropical island is bright red in this image, which is made from both visible and infrared light. So, the change could be more drmatic than "the simple picture" above.

Such evolution is common in earthquake zones in the Pacific and Indian Oceans. During the December 26, 2004, earthquake that generated the massive Indian Ocean tsunami, Simeulue Island was lifted as much as 150 centimeters (4.9 feet), exposing the reef that surrounded it.
In the picture, mounds of coral that were thrust out of the water by the quake died back to the water line. In locations where satellite images weren’t available, often because of persistent clouds, Meltzner and his colleagues relied on field measurements of the amount of uplift of coral mounds. Here a scientist measures coral uplift around Simeulue Island. (Photo copyright © John Galetzka.)





And it wasn't "enough". We can look at the geologic changes after the huge earthquake at the end of 2004 from the images below.

Through a combination of satellite imagery and field measurements, Meltzner and his colleagues developed a comprehensive picture of subsidence and uplift resulting from the Aceh quake. Colored dots represent estimates of minimum uplift or subsidence (sinking). The dashed line is the estimated pivot line, on either side of which the earth either rose or fell. Land predominantly sank around the Nicobar Islands, both sank and rose around the Andaman Islands, and predominantly rose around Simeulue Island. The satellite-based map showed that the earthquake rupture stretched nearly 1,600 kilometers along the fault—100 kilometers farther north than previous estimates suggested. (Map adapted from Meltzner et al., 2006.)

And maybe the geologic changes above, can lead us to another geologic phenomenon, Mud Volcano, happens also in Indonesia, at Sidoarjo. What kind of geologic changes will it come ???


news and article source : http://earthobservatory.nasa.gov