Evidences of the destruction of pre-hispanic populations by lahars from Cayambe volcano (Ecuador) and implications for future eruptive periods

Abstract

Since approx. 800 A.D. until Inca invasion in 1500, the Caranqui culture occupied the region where nowadays the city of Cayambe (Ecuador) is located. Their settlements expanded uphill along the western flanks of the Cayambe volcano, following the Blanco River, where agricultural land is most productive. Cayambe volcano, with several eruptions over the last 4000 years, must have posed many challenges to pre-Hispanic populations inhabiting this zone. The Blanco River is one of the main drainage systems of the volcano and, in case of an eruption, it is very plausible to assume that lahars flowed down the river and gravely affected nearby settlements. The aim of this study was to prove this hypothesis by inspecting “La Remonta” area, which is located over the right margin of the Blanco River and which is currently being rapidly urbanized by the growing city of Cayambe. During fieldwork various lithic fragments made in obsidian and andesite (e.g. arrowheads, scrapers, splinters and millstones) and ceramics (pottery) were found within a lahar deposit. Most of the collected fragments are not indicative of a specific culture. Nevertheless, the absence of decorations, their smooth and simple surface, their thick walls (9-20mm) and carbon particles found within them suggest that they were of domestic use and that the population they were used by lived off of agriculture, hunting and aquaculture. Some ceramic fragments with red paint and slip, and the specific shape of other elements are similar to one type of vessel that belongs to the first phase of the Caranqui culture (800-1250 A.D.). This finding allows determining a relative age of this destructive event, which could be most likely linked to the strong volcanic eruption of the Cayambe in 880 A.D. In depth investigations of this archeological site, which would serve to retrace the exact location and extent of this Caranqui settlement, are currently impeded by rapidly growing agricultural lands and urban zones. Nonetheless, the findings of this study are very valuable to the community since they embody the hazard that could await settlements downstream of the Blanco River – taking into account that the Cayambe volcano has shown unrest since mid-June, 2016.

Full text

Evidences of the destruction of pre-Hispanic populations by lahars from Cayambe volcano (Ecuador) and implications for future eruptive periods
Since 1150 BP until Inca invasion in 450 BP, the Caranqui culture
occupied the region where nowadays the city of Cayambe (60km
NW of Quito, capital of Ecuador and 35,000 inhabitants) is located
(fig. 1). Their settlements expanded uphill along the western
flanks of the Cayambe volcano, following the Blanco River, where
agricultural land is most productive.
VS43C-210
Simbaña Edwin1, Vásconez Francisco2, Vásconez Müller Anais3, Meza Ernesto4, Andrade Daniel2
*edn.sm@hotmail.com, fjvasconez@igepn.edu.ec
1Universidad Católica del Perú –Lima, Perú
2Instituto Geofísico de la Escuela Politécnica Nacional –Quito, Ecuador
3University College Freiburg –Freiburg, Germany
4Universidad Politécnica Salesiana –Quito, Ecuador
We inspected “La Remonta”area, which is located over the right margin of the Blanco River and which is currently
being rapidly urbanized by the growing city of Cayambe. During fieldwork various lithic fragments made in obsidian and
andesite (e.g. arrowheads, scrapers, splinters and millstones) and ceramics (pottery) were found within lahar deposits
outcrops. We used those fragments to reconstruct their original shapes and compared these to artifacts known to have
been used by the Caranqui culture. By doing this we were able to estimate a relative age of the lahar events in which
the fragments were found.
Figure 3. Lahar deposit with several fragments of pottery and lithic tools at “La Remonta” area at the right riverside of the Blanco river, this deposit correspond to the
bottom of the sequence in our study dated back to 1070 BP. The yellowish lahar deposit at the bottom is attributed to be from 14ka according to Detienne et al., 2017.
The studies of Samaniego et al., 1998, 2002 & 2004 and Vásconez et al., 2017
allow us to identify the potential hazard zones due to lahars coming down the
Blanco river at the volcano’s western flank (fig. 5a).“La Remota” area, the
archeological site presented in this study, can be found within the hazard zone,
having been affected several times by such events.
Samaniego et al., 2004 found charcoal in a lahar deposit dated back to 1690 BP at
the end of the second phase (fig. 2). Our study identified three lahar deposits.
Based on the analysis of pottery fragments, we estimated a relative age of 1070
BP. for the lahar at the bottom of the sequence. Moreover, charcoal that was
found within the lahar at the top of the sequence was dated back to 1785 AD.,
corresponding to the last eruption of the Cayambe. This means that there must
have been at least three major eruptions over a period of 900 years. The findings
show that many lahars jeopardized pre-hispanic peoples settled in the area,
especially during the third main phase of activity of Cayambe volcano.
Even though we found many pottery fragments in the area we were not able to
delimitate the site of the affected settlement because we did not find
architectural features. Nonetheless, we believe that the site must have been
located some meters upstream from the outcrop (fig. 5b).
-Cayambe is an active volcano (last eruption in 1785). Lahars caused by the partial melting of the ice-cap (18 km2) flow
down the western drainages: Blanco, La Chimba and Guachalá rivers. This study presents new evidences of risks posed by
lahars during past eruptions of the volcano. Lithic and pottery fragments of the Caranqui culture found inside the lahar
deposits allow us to estimate a relative age of the first event at the begining of the third major phase of activity of the
volcano in 1070 BP and at the top of the sequence an absolute age of 1785 AD (C14). We identified at least three major
events during the last 900 years. Besides, Samaniego et al., 2004 reported about vessel fragments belonging to the end of
the second phase of activity of Cayambe volcano (1690 BP), those fragments were correlated with La Chimba tradition.
Several lahars have, over the years, destroyed several pre-hispanic settlements at the lower fank of Cayambe volcano,
where currently the city of Cayambe is located.
-The findings of this study are very valuable to the community since they embody the hazard that could await settlements
downstream of the Blanco River –taking into account that the Cayambe volcano has shown unrest since mid-June, 2016
(Special reports of the Cayambe volcano 1-5, 2016 & 1-2, 2017 Instituto Geofisico). It is important to keep in mind that such
events are likely to repeat in the near future, thus posing a high risk to presently urbanized areas.
Figure 4.a) arrowheads and scrapers b) ceramic fragment of Caranqui’s G-type crock found
at “la Remonta” area c) Caranqui crocks phase 1 (Oberem and Wurster, 1989).
Cayambe volcano, with several eruptions over the
last 4000 years (Samaniego et al., 1998; fig. 2), must
have posed many challenges to pre-Hispanic
populations inhabiting this zone. The Blanco River is
one of the main drainage systems (W) of the
volcano, in case of an eruption lahars flowed down
the river and gravely affected nearby settlements.
1. Introduction
Figure 1. a) Caranqui settlements in the northern Ecuatorian Andes (Ontaneda, 2011). b)
North flank of Cayambe volcano and its location in the regional setting. Photo: Perrault M.
May, 2015
b
a
2. Methodology
Most of the collected fragments did not allow us to identify which
type of vessel they belonged too, however, we are certain that they
belong to the Caranqui culture. The absence of decorations, their
smooth and simple surface, their thick walls (5-20mm) and charcoal
particles found within them suggest that they were mainly of
domestic use and that the population they were used by lived off of
agriculture, hunting and aquaculture.
More specifically, some ceramic fragments with red paint and slip
and the distinct shape of other elements point to one type of vessel
that belongs to the first phase of the Caranqui culture (1150 - 700
BP.) according to Oberem & Wurster, 1989 (fig. 4). This finding
allows us to determine a relative age of one lahar event, which
could be most likely linked to the strong volcanic eruption of the
Cayambe in 1070 BP (fig. 2). This eruption took place at the
beginning of the third major eruptive phase described by Samaniego
et al., 1998.
3. Results
References
•Detiennen, M., Delmelle, P., Guevara, A., Samaniego, P., Opfergelt, S., Mothes, P. (2017). Contrasting origin of two clay-rich debris flows at Cayambe Volcanic Complex, Ecuador. Bulletin of Volcanology
79:27, 2-14. DOI 10.1007/s00445-017-1111-2.
•Oberem Udo & Wurster Wolfgang (1989), Excavaciones en Cochasquí Ecuador 1964-1965. Verlag Philipp Von Zabern. Mainz Am Rhein.
•Ontaneda Santiago (2010) Historia de los Pueblos Precolombinos de la Sierra Norte del Ecuador. Catálogo del Museo de Arqueologia Regional de la Sierra Norte.
•Samaniego, P., Monzier, M., Robin, C., Hall, M.L. (1998). Late Holocene eruptive activity at Nevado Cayambe Volcano, Ecuador. Bulletin of Volcanology 59:451-459.
•Samaniego P., Eissen J-P., Monzier M., Robin C., Alvarado A., Yepes H. (2004). “Los peligros volcánicos asociados con el Cayambe”. Instituto Geofísico, Quito, 95 pp.
•Simbaña, E., Vásconez, F., Vásconez, A. (2017). Evidencias de la destrucción de poblados pre-hispánicos por lahares del volcán Cayambe en la Sierra Norte. Jornadas de Ciencias de la Tierra 8. Escuela
Politécnica Nacional, Quito - Ecuador.
•Vásconez, F., Andrade, D., Bernard, B., Hidalgo, S. (2017). “Delimitación de las zonas amenazadas por lahares en el drenaje occidental del Nevado Cayambe”. Jornadas de Ciencias de la Tierra 8. Escuela
Politécnica Nacional, Quito - Ecuador.
5. Conclusion
4. Discussion
Figure 5. a) Lahar hazard zone at the Western flank of the Cayambe
volcano b) 3D model showing the potential site of the old settlement
destroyed by the lahar event in 880 AC.
Old City
CARANQUI CROCKS PHASE 1
CROCK TYPE G
Figure 2. Chrono diagram of Cayambe’s events recorded during the past
4000 years (Samaniego et al., 1998).
0 = 1950 AD
years BP