Tectonic Plates, Earthquakes, and Volcanos

Cusco, and in the larger scale all of South America, is situated on the South American tectonic Plate.  The South American Plate has an interesting relationship with the surrounding plates.  The Cocos Plate and Nazca Plate (the remains of the Farallon Plate) are continually subducting under the western edge of the South American Plate.  It’s this subduction that is responsible for the lifting the Andes.  It is also the cause for the volcanos that are strewn throughout them.  Peru is known for having a shallow dip in subduction which would lead to less volcanic activity in Cusco.    

 You can see from the volcanic activity map that most volcanos are located in southern Peru.  The closest volcano to Cusco is Quimsachata, whose last explosion has been posited to be around 4450 b.c.e.  The interface of these tectonic plates along the Peruvian coast has caused many earthquakes in the past.  There are three recorded earthquakes for Cusco: January 30^th 1943, May 21^st 1950, and April 6^th 1986.  The earthquake in May of 1950 had a magnitude of 7.0 and caused 1,625 deaths.