Wednesday, February 23, 2011

The New Madrid Seismic Zone: Much Ado About Something ... Unexpected

In 1811 and 1812, four major earthquakes (M7.4 to M8 on the Richter scale) centered in New Madrid, Missouri changed the course of the Mississippi River near Memphis, and may have caused the river to flow temporarily upstream. The entire fault system has been named after those earthquakes' epicenter. The biggest part of the New Madrid system sits in Missouri; it then extends along the Mississippi River Valley from northeast Arkansas through southeast Missouri and into western Tennessee and western Kentucky. The more than 4,000 earthquakes recorded there since 1974 make it the single most active fault system in the United States.

Is a "big one" centered in New Madrid on the near horizon? Anxiety runs high, and the local data are fearsome.

Yet the New Madrid (pronounced New MAD-rid) seismic zone is a mid-continent, or intraplate fault system, a rift occurring within the interior of a tectonic plate, and that may be key in forecasting the fate of the New Madrid area. Publishing in the journal Lithosphere, Mian Liu, professor of geological sciences at the University of Missouri-Columbia, Seth Stein, professor of earth and planetary sciences at Northwestern University, and Hui Wang, a Chinese Earthquake Administration researcher, suggest that widespread concern about the New Madrid area may be misplaced—literally. Examining about 2,000 years of records of mid-continent earthquakes from China, they found that big earthquakes never struck twice in the same place. Rather, after an initial earthquake, a series of aftershocks quaked the immediate area, sometimes with intensity approximating that of the initial shock. Additional trembling sometimes occurred with astonishing frequency over hundreds of years. The next major earthquake, however, was always further along the fault system. The investigators' GPS data show that an earthquake and prolonged resettling on one spot of a fault system inevitably increases tectonic stress on other sections of the system.

All of which suggests that New Madrid itself will probably not host the next mid-continent big one. On the other hand, St. Louis and Memphis—both of which are heavily populated, and situated near the furthest reaches of the New Madrid fault system—might. It could be what FEMA calls a "maximum of maximums" event. In anticipation of such a catastrophe, FEMA will lead a national-level exercise in May of 2011. Federal, state, and local governments will be involved, as well as businesses, private groups, and even faith-based groups. As May approaches, FEMA will make more exercise information available.

Monday, February 21, 2011

Species Assault is a Go

If it weren't nonfiction, it might be the definitive computer nerd thriller. "The computer says you must now die, and this is how it will happen." Really. And "the state" controls the computer.

But it's not necessarily as Orwellian as it sounds. For it's pest control of the animal variety that's the topic. Australia is spectacularly beset by non-native, invasive species introduced over the years in misbegotten attempts to have exotic pests "bio-control" populations of domestic ones. (One famous example: In 1935 enormous Hawaiian toads were let loose in Australian sugar cane fields to control cane beetles. But as things turned out, the beetles clung near the tops of the stalks, and as high as they jumped, the bottom-heavy toads couldn't reach them. The toads proved to be voracious omnivores. At the same time, they multiplied rapidly and spread diseases among indigenous species.)

Now, according to the first issue of the journal Methods in Ecology and Evolution, a computer application developed by ecologists at the University of Adelaide in Australia offers wildlife managers Spatio-Temporal Animal Reduction (STAR), a spreadsheet of tested culling strategies and options. Cut. Paste. Copy. Move. Deelte. Goodbye feral pigs, buffalo, horses, and other fiendishly foreign fauna. Species assault is a "go."

What Doesn't Kill You Makes You Older

Elizabeth Blackburn of UC San Francisco is part of a three-person team that won the 2009 Nobel Prize in Physiology or Medicine for the 1978 discovery of telomerase, the enzyme that lengthens and stabilizes telomeres. (Telomeres are DNA-protein complexes that cap the ends of chromosomes. As Blackburn explains it, they function like the tips on shoe laces, and protect chromosomes from fraying. However, each time a cell divides, some of the telomeres are used up. Below a critical telomere length, the cell loses its ability to reproduce itself. By replenishing telomeres with each cell division, telomerase plays a critical role in cell health and life span.)

In a landmark study of mothers of chronically ill children that was published in 2004, Blackburn reported that the mothers with the longest-term stress (the mothers with the oldest chronically ill children) had chromosomes with the shortest telomere tips. She and fellow researchers attributed the shorter lengths to diminished serum levels of telomerase, and estimated that during their years of stress those mothers' white blood cells had prematurely aged by 9-17 years.

Now Blackburn is suggesting that the aging news is not all bad for the chronically stressed, for with knowledge comes power. In studies published in 2009 and 2010, some subjects studied actually enjoyed increased telomere length over time. These findings opened the door to the search for factors that can help people lengthen telomoeres. Studies published in 2010 pointed to meditation, exercise, and, for women, delayed menopause.

According to Blackburn, the take-home message for chronically-stressed people who don't want to prematurely fall prey to age-related illness and debility is this: "Work hard. Play harder."

Tuesday, February 01, 2011

Diamonds Are Forever. Extinction Isn't.

In Australia, researchers at the University of Queensland have compiled a global database on mammals identified as "missing" (a category to which they assign extinct species as well as those "critically endangered and possibly extinct"). The database includes records dating as far back as 1500. In the September 2010 issue of Journal Proceedings of the Royal Society B, mammal ecologist Diana Fisher and statistical ecologist Simon Blomberg report that of the 187 missing species, 67 have been rediscovered. Based on their analysis of factors like date of last sighting and probable cause of extinction, they offer advice for conservationists. Mammals that are wide-ranging, have been missing for not more than 100 years, and are believed to have been killed off by habitat loss are most likely to be recovered; those killed off by predators, disease, or hunting are least likely. Unfortunately that second group includes charismatic mammals like the Tasmanian tiger, for which 25 major searches and countless amateur hunts have been launched. Those bad-bet expeditions happen at the expense of better-bet efforts to save non-celebrity species like the Australian lesser stick-nest rat, thought to have met its end through habitat loss. The researchers advise conservationists to check their data, not their hearts, and apportion their resources to species with a reasonable chances of recovery.