Geological Factors in Engineering

While most Americans celebrated Labor Day, got their children ready for school, or followed-up on a promise to spend one more weekend camping with the family in the great outdoors, the people of New Orleans evacuated their city and prayed for a safe return home. Hurricane Gustav made landfall about 70 miles southwest of New Orleans near Cocodrie, Louisiana. The storm weakened to a Category 2 hurricane before making landfall and degraded to a tropical storm shortly afterwards, but what was the cost of this storm that almost devastated New Orleans?

Can we keep building-up a city and key port while the great Mississippi River wants to redirect itself? Is it a best-case scenario to let ruins wash away into the Gulf of Mexico? The cost of the infrastructure that redirects the Mississippi River has risen to new levels as the Army Corps of Engineers prepares for the worst-case scenario. Levees need to be designed to withstand forecasted Category 5 storm surges. Careful calculations are being made as existing levees subside and fluvial deposits accumulate.

The all-important river ways, like the MRGO (Mississippi River Gulf Outlet), are being dredged year in and year out as fluvial deposits accumulate and fresh water marshes dissipate, amplifying the problem. Now that legislation will close the MRGO, and a replacement may not be completed for some time, what is the value of rebuilding infrastructure? Does it make sense to build a ship lock capable of accommodating deep-draft ocean-going vessels in the Industrial Canal? Can we relocate the inner harbor near the mouth of the Great Mississippi? Will government re-evaluate the economic value of the man-made waterways? Where and when will the most valuable port in the Gulf of Mexico and possibly the Eastern seashore get relocated?

Editor's Note: See also New Orleans: 'Til the Levee Breaks.

References:

http://www.independent.co.uk/news/world/americas/new-orleans-levees-hold-as-gustav-winds-down-916289.html

http://ap.google.com/article/ALeqM5j5xaEa4Wv3gC2Qstwu-p7281EQwgD92UJ3HG0

http://online.wsj.com/article/SB122029497789087839.html?mod=googlenews_wsj

http://www.ccmrgo.org/

http://mrgo.usace.army.mil/

Do areas of persistent volcanic activity that burn through the lithosphere, the part of Earth's outer layer that contains the crust and the upper part of the mantle, remain in a fixed location as to act as a reference point? Can we use remnants of persistent volcanic activity in the ocean floor to track tectonic plate motion?

Areas like the Hawaiian Islands and large calderas as thought to exist in Yellowstone Park in Wyoming are fed by hot-spots. In common terms hot spots are more or less exactly what the name implies. They are isolated areas of increased heat flow that convect magma from deep within our earth and persist over geological time spans.

Hot-spots are theorized to originate in the upper mantle or as deep as the core-mantle boundary where the D" Layer, a theoretical thin layer of the earth separating the liquid outer core from the solid inner mantle and accompanied by a defiant change in seismic waves and crystal structure of existing rock mass, exists. They do not streamline right to the surface, but rather feed large plumes of hot magma that flow through cracks and find the path of least resistance as the attempt to surface.

They can either cause extrusive or intrusive igneous bodies to form. Extrusive, meaning they surface through volcanic activity or intrusive meaning they do not surface, but rather cool and solidify within the crustal segment of the lithosphere.

As you may recall from reading "China's Earthquake and the Indus-Yarlung Suture Zone", plate tectonic theory divides Earth's crust into thin, rigid segments that move horizontally and adjoin other plates. Hot-spots are thought to remain in a fixed location as tectonic plates float and pass over the plume of hot magma that is fed by these laminar-like flow patterns.

The Hawaiian Islands may be the best example of how a hot spot that feeds island volcanoes has seemingly remained in a fixed location for at least 40 to 80 million years. The erupting magmas have formed what is presently referred to as the Hawaiian-Emperor seamount chain. There is an obvious change in the Pacific Plate motion around 50 to 40 MYA. Other than the sharp bend observed during this time frame, the plate seems to move uniformly. Is this abnormal and can we rely on the superposition of these laminar-like flow patterns to dispel plate motion?

Resources:

http://www.platetectonics.com/book/page_17.asp

http://www.gasd.k12.pa.us/~dpompa/Mini%20Lecture.html

http://en.wikipedia.org/wiki/Hotspot_(geology)

http://www.wwnorton.com/college/geo/egeo2/content/animations/2_6.htm

http://www.gps.caltech.edu/~gurnis/Movies/Animated_GIFs/Pyre_global-plume.gif

http://www.cems.umn.edu/research/wentzcovitch/highlights/science_now_040324.htm

Humanity ignores that which does not improve its lot. If it doesn't provide a measurable, sizeable ROI or immediate gratification, we're not interested. Man's burden is amplified as we are all users. We use all of the available resources until famine, inflation and the cost of living change how we must live – all while longing to live in a way we do not.

Often for the benefit of the few, societies exhaust their resources or deprive other groups of theirs. Today, land itself is the most limited resource. Its cost is determined by entrepreneurs who compete for what's left to develop. Industrialized civilizations have controlled rivers and destroyed ecosystems. We have consumed precious metals and raw materials. We continue to debate about the "green alternative" and the fight against climate change while our comfort and self-benefit continues to dominate our decisions.

Perhaps the most controversial topic regarding our ignorance of evolution is how we resist "energy evolution". Economics tells us that infrastructure and overhead costs might not outweigh the benefits of the combustion engine. Should we eighty-six it along with our dependence on non-renewable energy sources?

In his book "Energy Revolution: Policies for A Sustainable Future," Howard Geller outlines some of these problems. Geller's book talks about being energy-efficient and recognizes ethanol and gas turbines as clean energy technologies. Yet this only scrapes the surface of how far we need to dig.

The National Renewable Energy Laboratory (NREL) is treading water to support the manufacturers of solar cells that are not ready to power our nation - even with annual growth of 74% in 2007. This same organization, dedicated to developing renewable fuel sources, supports cellulosic ethanol. Will corn stoves and sugar cane bagasse prove to have a positive net-energy ratio? New infrastructure and other upstream costs may not take into account the removal of valuable biomass that may best be suited to help fertilize for future crop yields.

So I ask you these questions. What is really "economical"? How do we plan for the future? Do regulations overburden the so-called green alternative? Can the United States remain dominant as we convert ourselves into a service-oriented nation?

Resources:

http://www.nationalcenter.org/NPA572.html

http://www.signonsandiego.com/news/world/20080415-0919-unesco-foodprices.html

http://books.google.com/books?id=egl8XI2ZqXMC&pg=PA102&lpg=PA102&dq=overhead+energy+revolution&source=web&ots=QzPaeShYlx&sig=H5fBRPHJEl068Rf-g5GaijDJg7w&hl=en&sa=X&oi=book_result&resnum=1&ct=result#PPA34,M1

http://www.nrel.gov/

http://www.marketwatch.com/news/story/solar-panel-makers-scramble-lock-polysilicon/story.aspx?guid=%7B2A4F31B4-46E3-4C56-AA0B-820A13FE0826%7D

http://www.firstscience.com/home/articles/big-theories/nuclear-fusion-energy-for-the-future_17006.html

Dynamics associated with the Indus-Yarlung Suture Zone threaten China weeks after the deadliest earthquake in that nation's modern history. This week's aftershocks, measuring as great as 5.0 on the Richter scale, impede relief efforts and showcase the instability of the Tibetan Plateau. A suture zone is defined as the area of collision between two continental tectonic plates. There are several active suture zones in the world, but the recent collision between the Indian and Eurasian plates is a perfect example.

There are three basic ways in which the two tectonic plates can interact. First, there can be divergence or rifting and the forming of new oceans. There can also be lateral displacement or strike-slip faults, as observed by the infamous San Andres fault in the continental United States. Finally, there is a convergent plate boundary, which is associated with the subduction of oceanic plates and collision of continental plates.

Continental plates differ from ocean plates by composition, thickness and behavior. They are composed of lighter silicate material that is buoyant, and which floats on the dense mantle material. They are also considerably thicker than oceanic plates. When the buoyant large land mass converges with another plate, it will either subduct the denser oceanic plate or resist subduction itself by forming accretionary prisms and suture zones. The lighter material is always pushed back towards the surface due to a density gradient.

When a collision of continental plates occurs, there are a series of events that take place over millions of years until the two land masses merge together, forming a larger tectonic plate that will behave as a single object. During the preset, there is an approaching land mass with related continental shelf and ocean plate material that is subducted by the larger plate. Then, as the lighter buoyant continental plate material approaches, there is resistance to the subduction complex, accretion of material and the creation of a suture zone.

The suture zone - area of collision - has a tremendous amount of stress related with it. Low angle thrust faults displace the buoyant material. The formation of excessively thick plate material and large mountains creates a very unstable environment. Heavily folded rock bands and metamorphic rocks known as mylonites help describe the high-stress, low-temperature rock alterations that occur. Erosion rates are significantly high and the young unstable mountain chains are prone to failure. The high-stress environment is relieved temporarily by the large earthquakes, as observed in China and the Tibetan Plateau.

A suture zone is, without a doubt, one of the most geologically unstable environments known to humanity.

References:

http://en.wikipedia.org/wiki/Indus-Yarlung_suture_zone

http://www.alcwin.org/Dictionary_Of_Geology_Description-236-S.htm

http://www.ipgp.jussieu.fr/~cogne/pub/site_perso/Mes%20papiers/1993_Configuration_Asia.pdf

http://tectonics.caltech.edu/publications/pdf/BettinelliJGEOD2006.pdf

http://en.wikipedia.org/wiki/Plate_tectonics

http://www.seismo.unr.edu/ftp/pub/louie/class/100/plate-tectonics.html

Radon, a deadly, odorless carcinogen may exist in your home – whether you know it or not. As one of the heaviest elements found in the gaseous state, radon can build up to lethal concentrations in basements and low lying areas. Exposing yourself to rather low concentrations of radon will increase your chances of developing lung cancer. Radon is second only to smoking as the leading cause of lung cancer in the United States today.

So what is Radon? Radon is an unstable, radioactive daughter product of the uranium decay series. The unstable Uranium-234, breaks down to Thorium-230, to Radium-226, and then Radon-222. Radon goes through further mutation, giving off Beta and Alpha particles until it reaches a stable state at Pb-206 or Lead-206. Even though the half life of radon is only 3.8 days, it is the only daughter product that is found in the gaseous state and can easily enter your body through your reparatory organs.

Where does radon come from? As cited above, radon comes from the breakdown of Uranium-234. Uranium can be found as a naturally occurring element in soils, so the point source of radon is the ground we walk on and the water we drink. Houses and other structures that have wells and sump pumps allow radon to travel through larger distances and accumulate in your house or basement.

The safest practice is to sample the air quality in your house and/or basement, and insure that radon does not exceed its legal limits. If you do have a problem with your air quality, ventilation systems are able to reduce radon concentration to below legal limits. The safest bet is to test your house and take the necessary actions.

Resources:

http://www.epa.gov/radon/pubs/citguide.html

http://www.epa.gov/radon/

http://en.wikipedia.org/wiki/Radon

http://www.stuk.fi/tutkimus/luonnonsateily/en_GB/tekijat/