Southern Peru desert shattered by the great 2001 earthquake: Implications for paleoseismic and paleo-El Niño–Southern Oscillation records

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   Fig. 1.

   Location of the seismically shattered desert landscape in southern Peru; epicenter and main aftershocks of the June 23, 2001, earthquake and principal cities in the region (from the U.S. Geological Survey); inferred fault rupture of the 2001 earthquake (from ref. 5); and inferred epicenter of the 1604 earthquake (from ref. 18).

   
   
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   Fig. 2.

   Rock fall in the lower Ilo valley, one of several thousand mostly disrupted landslides triggered by the 2001 earthquake.

   
   
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   Fig. 3.

   Collapsed quebrada banks in the shattered landscape. (A) Collapse of banks composed of cohesive crust underlain by largely cohesionless sand produced a deposit consisting of a mixture of large blocks and sheets of loose, fine sediment. The scale shown is marked in inches and centimeters. (B) Detachment of large polygonal blocks, on the order of 1 m long, significantly widened this quebrada channel while also providing substantial amounts of sediment for entrainment by postearthquake runoff. Dark patches on the ridge in the background are zones of shattered ground. (C) Sediment from seismically shattered banks choking the bottom of a quebrada. The scale shown is marked in inches and centimeters.

   
   
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   Fig. 4.

   Multiple rills widened by earthquake-induced collapse of their banks. Rills in the foreground are ≈0.1–1.0 m wide.

   
   
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   Fig. 5.

   Zones of cracked and shattered ground on ridge flanks. (A) Zone in which surficial materials have been shattered into fragments a few millimeters to a few centimeters on a side. The scale shown is marked in inches and centimeters. (B) An earthquake-induced ground crack (upper part of photograph) follows the trace of an older ground crack filled with aeolian sand (light material in lower part of photograph), as shown in shallow excavation. The scale shown is marked in inches and centimeters. (C) Zone of cracked ground grading into a zone of shattered earth. The scale shown is marked in inches and centimeters. (D) Closely spaced zones of shattered ground (dark areas) on hillslope. Note the unpaved road traversing the central part of the photograph for scale.

   
   
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   Fig. 6.

   Effects of the June–July 2002 rainfall event on the shattered landscape. (A) Earthquake-induced ground cracks provided channels for runoff, which eroded the edges of polygonal blocks and entrained sandy sediment in flow. The scale shown is marked in inches and centimeters. (B) Fan-shaped deposit of sediment (light-colored material) washed over an unpaved road from an earthquake-widened rill.