The Rosas-Julumito Fault ( es, Falla de Rosas-Julumito) is an oblique dextral
strike-slip fault
In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...
in the
department
Department may refer to:
* Departmentalization, division of a larger organization into parts with specific responsibility
Government and military
*Department (administrative division), a geographical and administrative division within a country, ...
Colombia
Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...
. The fault is part of the megaregional
Romeral Fault System
The Romeral Fault System ( es, Sistema de Fallas (de) Romeral) is a megaregional system of major parallel and anastomosing faults in the Cordillera Central (Colombia), Central Ranges of the Colombian Andes and the Cauca Basin, Cauca, Amagá Basin, ...
and has a total length of and runs along an average northeast to southwest strike of 026.9 ± 7 in the
Central Ranges
Central Ranges (code CER) is an Australian bioregion, with an area of 101,640.44 square kilometres (39,244 sq mi) spreading across two states and one territory: South Australia, Western Australia, and the Northern Territory.Andes. The fault is associated with the
1983 Popayán earthquake
The 1983 Popayán earthquake ( es, El Terremoto de Popayán) occurred on 31 March in Popayán, Colombia. It had a Richter magnitude scale, magnitude of at least 5.5 with an epicenter south west of Popayán at a depth of . The earthquake killed 26 ...
that partially destroyed Popayán, the capital of Cauca, and led to more than 300 fatalities. A maximum moment magnitude earthquake of 6.8 is estimated for the fault.
The Rosas-Julumito Fault is part of the Romeral Fault System. It is a rather short section of about length, of which have active tectonic movement. The fault section parallels the Cauca-Almaguer Fault, which is one of the largest older fracture zones in western Colombia. The Rosas-Julumito fault runs about west of the city of Popayán. The fault crosses the Pliocene to PleistocenePopayán Formation, which consists of pyroclastic flow, mud flow and ash-fall deposits. It is believed that either the Rosas Fault or the nearby Julumito Fault (less than to the west) produced the earthquake of March 31, 1983 that partially destroyed the city of Popayán.
The fault section runs through the smooth but hilly topography that is formed by sediments of the Popayán Formation. The fault morphology is easily observed on aerial photographs and satellite images and from aircraft. The most noticeable features are fault saddles, ponded
Quaternary
The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...
alluvial valleys, stream deflections, offset drainages, linear fault ridges, and shutter ridges. Beyond the Popayán Formation, where the fault is in older rock formations, the topographic expression of the fault is still noticeable.
Activity
The fault is associated with the devastating 1983 Popayán earthquake (Mw 5.5) that caused more than 300 fatalities. During the 1983 earthquake, several cracks with generally north trends developed at the surface in an area wide and long, north of Popayán. Individual cracks were a few meters to tens of meters long and few millimeters in width. A maximum moment magnitude of 6.8 is assumed for this fault using only for its probable total surface rupture length.