The Muralla Pircada—an ancient Andean debris flow retention dam, Santa Rita B archaeological site, Chao Valley, Northern Perú

Abstract

Debris flows caused by El Niño events, earthquakes, and glacial releases have affected northern Perú for centuries. The Muralla Pircada, a northeast-trending, 2.5 km long stone wall east of the Santa Rita B archaeological site (Moche-Chimú) in the Chao Valley, is field evidence that ancient Andeans recognized and, more importantly, attempted to mitigate the effects of debris flows. The Muralla is upstream from the site and is perpendicular to local drainages. It is 1-2 m high, up to 5 m wide, and is comprised of intentionally-placed, well-sorted, well-rounded, 20-30 cm cobbles and boulders from nearby streams. Long axes of the stones are gently inclined and parallel local drainage. Case-and-fill construction was used with smaller cobbles and pebbles used as fill. Pre-Muralla debris flows are indicated by meter-sized, angular boulders that were incorporated in-place into construction of the dam and are now exposed in breeches in the dam. Post-Muralla debris flows in the Chao Valley are indicated by meter-sized, angular boulders that now abut the retention dam.

Erosion and morphology of a debris flow caused by a glacial lake outburst flood, Western Norway

“…Surface water flow is one of the most common triggering mechanisms for debris flows in high mountain regions (Brooks et al 2005;Tognacca et al 2000). Debris flows commonly result from excess rainfall or snowmelt in combination with loose erodible material in steep valleys.…”

Landslides: a review of achievements in the first 5 years (2004–2009)

“…Case studies of rock falls and rockslides included Orwin et al (2004) in Canada, Strouth et al (2006) in the USA, Catane et al (2007) in the Philippines, Cox and Allen (2009) in New Zealand, and Corominas et al (2005a) in the Pyrenees between France and Spain. Case studies of debris flows included Brooks et al (2005), which dealt with an ancient Andean debris flow in Peru, in China, and also Breien et al (2008) in Norway. Debris flow case studies were included in a special thematic issue "Debris flow hazards" (vol.…”

Coal and Cremation at the Tschudi Burn, Chan Chan, Northern Peru*

“…Natural hazards such as El Niño floods, mudflows ( huaycos ) and earthquakes have affected Perú for centuries (Stillwell 1992; Brooks et al 2005) and perhaps, as in South‐East Asia, the decomposing bodies of the victims of an ancient tsunami in northern Perú may have been cremated using locally available fuel such as coal. Tsunamis have struck northern Perú: in 1960, three lives were lost to a 9 m, earthquake‐generated tsunami that struck near Chimbote; and in 1996, 12 people were killed by a 5 m tsunami that struck the same area (Tsunami Research Group 2005).…”