Earth Science Discoveries

1. Earth's Core (1906)
Seismologist Richard Oldham determines that earthquake waves move through the central part of the Earth much slower than through the mantle around it. He surmises that the Earth has a core composed of liquid.

2. Earth's Inner Core (1930s)In 1936, Inge Lehmann documents that some seismic waves from deep inside the Earth's core do not pass through, but are reflected back. It becomes clear that the Earth has an inner core consisting of a small, solid iron sphere that is surrounded by a thick outer core composed of liquid iron.

3. Continental Drift (1911)
Alfred Wegener proposes that all the continents in the world once formed a single, giant landmass that was eventually split apart in a process called "continental drift." Wegener's evidence consists of the "fit" of South America with Africa, fossil distribution and geological similarities.

4. Seafloor Spreading (1950s – 1960s)
Adding his own data on changes in seafloor depth and geology to discoveries of his peers, Harry Hess proposes that Wegener's theory of continental drift is a result of seafloor spreading. He hypothesizes that molten magma from beneath the Earth's crust is oozing up between the plates in the Great Global Rift (now referred to as the Mid-Ocean Ridge). As the hot magma cools, it expands and pushes the plates out from the rift, causing the Atlantic Ocean to get wider over time.

5. Plate Tectonics (1960s)
The work of many scientists reveals that the Earth's surface is broken into several interconnected plates of rock. Earth's outermost layer, the lithosphere, is broken into at least seven large, rigid pieces. These plates are moving in different directions and at different speeds (about 1 to 4 inches per year) and are crashing together, pulling apart and sideswiping each other. All the action at plate boundaries produces phenomena such as mountains, volcanoes and earthquakes.

6. Troposphere and Stratosphere (1890s)
With the aid of scientific instruments placed on unmanned balloons, Leon Teisserenc de Bort discovers that the atmosphere consists of layers. Bort notices that air temperature decreases steadily up to about seven miles, but remains constant at higher altitudes. After more than 200 balloon experiments, he suggests that the atmosphere is divided into two layers called the "troposphere" and the "stratosphere."

7. Global Warming (late 20th century)
A number of scientists see evidence of a warming trend on the Earth's surface and attribute it to a rise in the concentration of "greenhouse gases." Global warming theory states that an increase of the average temperature of Earth's atmosphere and oceans since the late 19th century can be attributed to humans and increased emissions of carbon dioxide. According to the theory, temperatures will increase further if emissions of these greenhouse gases continue.

8. Cosmic Radiation (1911 onward)
In 1912, Victor Hess travels to 17,500 feet in a hot air balloon (without oxygen) and observes that radiation increases with altitude. Further experiments convince him the radiation is coming from space. We now know that the vast majority of cosmic rays are protons, and therefore have a positive electrical charge.

9. Magnetic Field Reversal (1906)
Bernard Brunhes discovers that the Earth's magnetic field has changed direction and reversed itself. His paleomagnetic study of clay baked by a Miocene lava flow 13 million years ago provides the evidence. It is nearly 50 years before his discovery is accepted by the scientific community.

10. Geological Change (1830s)
Charles Lyell offers proof that the Earth evolved slowly in his multivolume Principles of Geology: An Attempt to Explain the Former Changes of the Earth's Surface by Reference to Causes Now in Operation, published between 1830 and 1833. In his work, he advocates the then-controversial idea of uniformitarianism — the idea that the Earth was shaped entirely by slow-moving forces acting over a very long period of time. Catastrophism, a geologic idea that uses biblical chronology to date the Earth, was more accepted at the time.

11. Radiometric Dating (1907)
Bertram Boltwood discovers how to calculate the age of a rock by measuring the rate of its radioactive decay. His observations and calculations put Earth's age at 2.2 billion years. Although we now think the Earth is nearly twice that age, this number was a dramatic increase over the accepted age at the time. Boltwood's formulas are compatible with several radioactive elements, including carbon-14, which has been used to date historical artifacts.

12. Periodic Ice Ages (1930s)
Serbian astrophysicist Miultin Milankovitch develops a theory relating Earth's motion to long-term climate change and ice ages. His mathematical theory of climate uses variations in solar radiation based on season and latitude. His theory posits that cyclical variations in Earth-sun geometry, such as orbit shape and axis angle, result in different levels of solar energy reaching the Earth.

source : http://science.discovery.com

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

Significant Climate Anomalies 2006

Our mother earth suffers badly. The equilibrium disturbed. Unbalancing happens everywhere. In the depth of the ocean. On the surface of the land. Even in the air we always breathe. Below the the significant climate anomalies and events in 2006. They can be undeniable truth about how urgent our mother earth suffers. If we dont change our own habit, and maintain the way we treat her the way we used to do, then it's just a matter of time waiting the disaster after disaster.

image source : NOAA website

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

Earth

“ Earth provides enough to satisfy every man's need, but not every man's greed ”

(Mahatma Gandhi)