Civilsation will always defeat terror when it can do this….here are some string quartets on the 10th anniversary of September 11:

Steve Reich played by Kronos Quartet: WTC 9/11, downloadable on the nonesuch website

Joan Tower played by the Tokyo Quartet: In Memory, on itunes

Robert Sirota’s Triptych for string quartet recorded by the Chiara Quartet

Richard Danielpour’s String Quartet No.6, ‘Addio’ (I’ve not yet found a recording)

ML Wyatt: Quartet in Memorium of September 11th on youtube in 4 parts: