architecture

Saturday, August 23, 2008

Big One in the Big Apple

According to a newly published report in the Bulletin of the Seismological Society of America, New York City is more at risk from earthquakes than previously thought.

[Image: A seismic map of the mid-Atlantic, via PhysOrg.com].

What's interesting here, though, is not some disaster film scenario in which the city is shuddered into a rubble of broken bricks and glass, but the fact that the land around Manhattan is actually an "intricate labyrinth of old faults, sutures and zones of weakness caused by past collisions and rifting," as PhysOrg.com describes it.
Amazingly, for anyone who has ever studied architecture, they even describe "unseen but potentially powerful structures whose layout and dynamics are only now coming clearer." Gilles Deleuze must be rolling in his grave.
In a long excerpt, worth reading in full for its structural exploration of the land surrounding New York City, we read:
    One major previously known feature, the Ramapo Seismic Zone, runs from eastern Pennsylvania to the mid-Hudson Valley, passing within a mile or two northwest of Indian Point. The researchers found that this system is not so much a single fracture as a braid of smaller ones, where quakes emanate from a set of still ill-defined faults. East and south of the Ramapo zone – and possibly more significant in terms of hazard – is a set of nearly parallel northwest-southeast faults. These include Manhattan's 125th Street fault, which seems to have generated two small 1981 quakes, and could have been the source of the big 1737 quake; the Dyckman Street fault, which carried a magnitude 2 in 1989; the Mosholu Parkway fault; and the Dobbs Ferry fault in suburban Westchester, which generated the largest recent shock, a surprising magnitude 4.1, in 1985.
The 125th Street fault? The Dyckman Street fault? The Dobbs Ferry fault? It was already clear that the built geography of Manhattan has been thoroughly determined by tectonic prehistory, but what future faults might yet be discovered down there – an Empire State fault, a St. Mark's Bookshop fault (with huge diagonal fissures extending infinitely down from the Critical Theory section), a Lower East Side fault whose all but imperceptible nighttime groaning gives new ideas to poets?
And shouldn't these faults be added to Google Maps?
Some of these underground structures were actually discovered during excavation work for new subways and water tunnels beneath the city, when digging crews came across sudden breaks in the rock seeming to slice off to nowhere. But if these "ill-defined" interruptions, as PhysOrg.com describes them, in the foundational security of New York City lead anywhere, it is to a "braid of smaller [faults]" that filigrees throughout the area. The whole eastern seaboard around Manhattan becomes a puzzlework of forgotten microcontinents – and someday, again, that puzzle might start to move.

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