hooray!

It's not every day you see an article about the use of isotopes in environmental tracing (a topic I happen to love), but today's NYT had this:

http://www.nytimes.com/2011/11/22/science/rare-krypton-81-isotope-helps-track-water-in-ancient-nubian-aquifer.html?src=dayp

This job does a good job of explaining just how geologists think about groundwater movement measurement using isotopic tracers. Gee, actual science news in a mass media outlet? Who wudda thunk?

misusing science on the phantom LA subway

An interesting AP article--"Beverly Hills bids to halt subway tunnel at school"--discusses recent stirrings toward expanding Los Angeles's inadequate subway system. This article does a good job of summarizing the myriad reasons why LA's people-moving system--and we can think of cars and subways and pedestrian walkways as all part of one large circulatory system--is so deeply broken.

To wit, people seem afraid that the proposed expansion, in a path under Beverly Hills High Schools, would:

--shake their houses

--risk the tunnel's collapse

--risk a methane explosion

But earthquakes are a big focus of their fears, with some subway advocates declaring, "It would be dangerous to have it under the school--God forbid, if we had an earthquake."

Well, LA is going to have earthquakes. Large earthquakes. There are few things in the world as certain as the continued seismic activity in California. But subways survive pretty well in quakes; in 1989, the Bay Area's BART system was largely unaffected. Where BART may be affected in the future are those points where the BART system connects to the land--elevated sections of track, hoisted up into the air on pillars placed on poor soil; the tunnels themselves will likely be fine (with the exception of one section that directly crosses the Hayward Fault). But the LA project is going to be entirely underground, making the "egg-shell" curvature of tunnels something that will reinforce their strength.

In any event, the unscientific approach of subway critics is shown by their insistence that things would be okay if only the subway were moved slightly away, toward the area of the Santa Monica Boulevard. Just not near their houses.

This is geologically ridiculous. What LA faces most acutely is shaking from blind thrust faults, which riddle the subsurface of the LA basin like cracks on a broken car windshield. Moving a location a few hundred meters one way or another will make virtually zero difference in shaking intensity.

The situation here is not analogous to the Hayward fault area, where a few hundred meters could make a difference between houses sitting directly on the fault being torn apart by the expected 2 meters of movement, while those some distance away might "only" come off their foundations. Thrust faults, by contrast, often do not cause surface disruption; the shaking is the prime danger, and a big quake will ring the entire LA basin like a bell hit with a hammer.

So in short, once again misunderstandings of geology are being used to promulgate non-rational ideas. Many great cities have great transit systems--London, NY, DC. These system move people efficiently and swiftly, and don't shake the ground or cause methane to explode as trains pass. If one wants to oppose public transit because one doesn't want "those people" in one's neighborhood, fine--be honest and explicit with those sentiments. But don't misuse science in the service of such ideas.