Earth and Atmospheric Sciences, Department of
Date of this Version
2011
Citation
Published in Salfity, J.A., and Marquillas, R.A., eds., 2011, Cenozoic geology of the Central Andes of Argentina: Salta, SCS Publisher, 458 p. ISBN 978-987-26890-0-1
Abstract
The north-south orient ation ofthe mo unta inous part ofthe Province ofSalta form s a massive barrier to easy communication between the more populate d region in the central pan of the provin ce and the communities to the west. Routes follow deeply entrenched valleys th at are frequ entl y th e sites ofdebris flows that cause disruptions in th e flow of traffic during the months of December through March , wh en most of the precipitation of the region is recorded . The steep topography and the tecton ic settings have resulted in nearly 150 large landslides and debris flows most ofwhich were identi fied through stereo scopic study of airphoros, scale 1/50,000 and l/70,00 0. More than 100 of these are in the Cordillera Oriental and Calchaq uenia, more than 30 were noted in the Pu na, a smaller number in the Sierra s Su bandinas. Several clus ters of large landslides in each of th ese rnorphos truc tural regions undoub tedly were trigger ed by earthquak es th at may have had a magnitude (Richter Scale) of5 .0 or greater; thus their locations provide addi tional information on the probable epicenters of preh isto ric earthq uakes. Most of the landslid es ident ified do not in themselves present any hazard or risk at thi s time. Their locat ion s and geo logic setting indicat e locations where un stabl e slopes have failed , wh ich provides a warn ing th at add itional slides co uld take place in similar setti ngs. Their identificat ion and location also serves as a guide to lan d- use planners of the pr ovince, so that if new construction is undertaken, measures to avoid reactiva ting old and now stable slide masses can be avoided.
Laorientacion meridional de la parte rno n tafiosa de la Provincia de Salta ha generado una barr era que no favore ce una Hcil y fluida comunicaci6n entre las regiones pobladas de la pane central de la provin cia y los pueblos del oeste. Las ru tas siguen los valles profundos donde los flujos densos y los der rumbes de roca interrumpen con frecuencia eI rrafico entre diciembre y rnarzo , cuando se registra la mayorfa de las precipitacio nes. La ropografia empinada y el marco tectoni co dieron como resulrado casi 150 deslizamientos y flujos de escombro s qu e fu eron identificados a rraves del examen de foros aereas, escalas 1/50.000 y 1/70 .00 0. De los movimienros en masa registrado s, mas de 100 oc urrieron en la Co rdi llera Oriental y Calc haquenia, mas de 30 en la Puna, y algunos cua ntos en las Sie rras Suba nd inas/S istema Santa Barbara. En cada una de las regio nes rnorfoestructurales se ubican grupos de grandes de rrumbes que deben haber sido causados por ter remoros con una mag ni tu d (Richte r) de 5.0 0 mayor. La ubi cacion de esros rasgos distinriv os prove e la informacion necesari a para facilitar la identi ficacion de epiceritros de terremoros prehistoricos. La mayoria de los de rrumbes localiza dos no indican riesgo alguno en la acrualida d. Mas bien, los sitios geologicos seleccionados ind ican lugares donde oc urr en pend ienres inestables que advierten sobre evenruales deslizamienros que pudieran ocurrir en esros lugares. La localizaci6n de esros sitios servira de guia para quienes planifican el uso del suelo y para evitar dafiosa obras civiles, accesos viales y, au n, la vida de las personas.
Comments
© SCS Publisher 2011