by Staff Writers
Washington DC (SPX) Apr 09, 2012
The Earth's crust beneath the Mississippi Delta sinks at a much slower rate than what had been assumed. That's one of the results geoscientists report in a paper published in the journal Earth and Planetary Science Letters. The researchers arrived at their conclusions by comparing detailed sea-level reconstructions from different portions of coastal Louisiana.
"The findings demonstrate the value of research on different facets of Earth system dynamics over long time periods," says Thomas Baerwald, geography and spatial sciences program director at the National Science Foundation (NSF).
NSF's Directorates for Geosciences and for Social, Behavioral and Economic Sciences funded the research.
"The results provide valuable new insights about the factors that affect shorelines and other locations in the Gulf Coast area now and into the future," says Baerwald.
"Our study shows that the basement underneath key portions of the Mississippi Delta, including the New Orleans area, has subsided less than one inch per century faster over the past 7,000 years than the more stable area of southwest Louisiana," says paper co-author Torbjorn Tornqvist of Tulane University.
The difference is much lower than previously believed.
"Other studies have assumed that a large portion of the Earth's crust underneath the Mississippi Delta subsided at least 30 times faster due to the weight of rapidly accumulating sediments in the delta," says Tornqvist.
The paper, co-authored by Tulane scientists Shi-Yong Yu and Ping Hu, reveals some good news for residents of the New Orleans area.
Large structures such as coastal defense systems could be relatively stable, provided they are anchored in the basement at a depth of 60-80 feet below the land surface.
Shallower, water-rich deposits subside much more rapidly.
However, the study also provides more sobering news.
"These subsidence rates are small compared to the rate of present-day sea-level rise from the Florida panhandle to east Texas," says Tornqvist.
"The rate of sea-level rise in the 20th century in this region has been five times higher compared to the pre-industrial millennium as a result of human-induced climate change."
Sea level has risen more than eight inches during the past century.
"Looking forward 100 years, our main concern is the continued acceleration of sea-level rise due to global warming, which may amount to as much as three to five feet," says Tornqvist.
"We can now show that sea-level rise has already been a larger factor in the loss of coastal wetlands than was previously believed."
Tectonic Science and News
Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.
Richard Branson headed to 'center of Earth'
New York (AFP) March 30, 2012
British tycoon Richard Branson may have lost his race to the bottom of the ocean, but not his sense of humor, declaring Friday a faux plan to top his rivals by voyaging to the center of the Earth. The impossible adventure was announced, tongue jammed in cheek, with the seriousness of a real campaign. "Sir Richard Branson to launch journeys to the center of the Earth through Virgin Volcan ... read more
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2012 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement|