Olca

The gasses emission is comprised by a single warm spring at the base{{Cite journal|last=Reyes|first=Nicolas|title=Geothermal Exploration at Irruputuncu and Olca Volcanoes: Pursuing a Sustainable Mining Development in Chile|url=https://www.geothermal-library.org/index.php?mode=pubs&action=view&record=1029363|journal=Geothermal Resources Council Transactions|pages=35}} and a persistent fumarole field over at the crater's dome for at least 60 years.{{Cite journal|last1=Franco Tassi|last2=Felipe Aguilera|last3=Orlando Vaselli|last4=Thomas Darrah|last5=Eduardo Medina|date=2011-06-30|title=Gas discharges from four remote volcanoes in northern Chile (Putana, Olca, Irruputuncu and Alitar): a geochemical survey|url=http://www.annalsofgeophysics.eu/index.php/annals/article/view/5173|journal=Annals of Geophysics|volume=54|issue=2|doi=10.4401/ag-5173|doi-access=free}} The fumarolic field is about 0.1 km² and the emissions measured in situ at the crater show a highly mixed magmatic system between high temperature gasses and hydrothermal fluids.

The gas composition indicates low concentration of H₂, CO and acidic gasses, and high concentration of H₂S and hydrocarbons. The carbon/sulfur ratios are high and the isotopic values suggest the mixture between magmatic, hydrothermal, and atmospheric fluids. Other techniques used to measure the amount of SO₂ includes remote sensing techniques called Differential Optical Absorption Spectroscopy(DOAS) giving maximum concentration of 35 ppm.m of SO₂;Clavero J., Soler V., Amigo A. 2006. Caracterización preliminar de la actividad sísmica y de desgasificación pasiva de volcanes activos de Los Andes Centrales del Norte de Chile. XI Congreso Geológico Chileno, Actas II, 443-446 (Spanish) and the most recent taken with a UV camera suggesting an average of 18.4 t d⁻¹.{{Cite journal|last1=Aguilera|first1=Felipe|last2=Layana|first2=Susana|last3=Rojas|first3=Felipe|last4=Arratia|first4=Pilar|last5=Wilkes|first5=Thomas C.|last6=González|first6=Cristóbal|last7=Inostroza|first7=Manuel|last8=McGonigle|first8=Andrew J.S.|last9=Pering|first9=Tom D.|last10=Ureta|first10=Gabriel|date=2020-07-02|title=First Measurements of Gas Flux with a Low-Cost Smartphone Sensor-Based UV Camera on the Volcanoes of Northern Chile|journal=Remote Sensing|language=en|volume=12|issue=13|pages=2122|doi=10.3390/rs12132122|bibcode=2020RemS...12.2122A|issn=2072-4292|doi-access=free}}

Different information exists regarding the activity and activity migration of Olca. There is a study dating two flows, which suggest a formation during the Pleistocene,{{Cite journal|last1=Worner|first1=Gerhard|last2=Hammerschmidt|first2=Konrad|last3=Henjes-Kunst|first3=Friedhelm|last4=Lezaun|first4=Judith|last5=Wilke|first5=Hans|title=Geochronology (40Ar/39Ar, K-Ar and He-exposure ages) of Cenozoic magmatic rocks from Northern Chile (18-22°S): Implications for magmatism and tectonic evolution of the Central Andes|url=https://www.researchgate.net/publication/279696890|journal=Revista Geológica de Chile|volume=27|pages=205–240}} while others suggest to be much older with the appearance of the edifices volcanic activity migrated east over time.{{Cite web|title=Olca & Paruma|url=https://volcano.oregonstate.edu/sites/volcano.oregonstate.edu/files/oldroot/CVZ/olcaparuma/index.html|access-date=2021-12-10|website=volcano.oregonstate.edu}} There is also evidence that glaciers were on the volcano in the late Pleistocene. The

Unconfirmed historical eruptions are suspected to have occurred in 1865–1867.{{Cite journal|last1=Pritchard|first1=M.E.|last2=Henderson|first2=S.T.|last3=Jay|first3=J.A.|last4=Soler|first4=V.|last5=Krzesni|first5=D.A.|last6=Button|first6=N.E.|last7=Welch|first7=M.D.|last8=Semple|first8=A.G.|last9=Glass|first9=B.|last10=Sunagua|first10=M.|last11=Minaya|first11=E.|date=June 2014|title=Reconnaissance earthquake studies at nine volcanic areas of the central Andes with coincident satellite thermal and InSAR observations|url=https://linkinghub.elsevier.com/retrieve/pii/S0377027314001395|journal=Journal of Volcanology and Geothermal Research|language=en|volume=280|pages=90–103|doi=10.1016/j.jvolgeores.2014.05.004|bibcode=2014JVGR..280...90P|url-access=subscription}} The last activity has been reported of low-intensity seismicity accompanied with fumarolic activity in November 1989 and March 1990 intense degassing.{{Cite journal|title=Global Volcanism Program {{!}} Report on Olca-Paruma (Chile-Bolivia) — March 1990|url=https://volcano.si.edu/ShowReport.cfm?doi=10.5479/si.GVP.BGVN199003-355050|access-date=2021-12-10|website=volcano.si.edu|language=en|doi=10.5479/si.gvp.bgvn199003-355050|url-access=subscription}} In 2010, there a campaign conducted seismic activity showing 3 potencial swarms without a clear interpretation.

File:Olca.jpg

• Ollagüe
• List of volcanoes in Bolivia
• List of volcanoes in Chile

{{Reflist}}

• {{cite gvp|vn=355050|name=Olca-Paruma}}

• [https://web.archive.org/web/20140814173747/http://www.ine.gob.bo/publicaciones/visorPdf.aspx?Codigo=050902&tipo=1 Population data and map of San Pedro de Quemes Municipality]

Category:Stratovolcanoes of Chile

Category:Volcanoes of Antofagasta Region

Category:Subduction volcanoes

Category:Volcanoes of Potosí Department

Category:Polygenetic volcanoes

Category:Bolivia–Chile border

Category:International mountains of South America

Category:Pleistocene stratovolcanoes

Category:Holocene stratovolcanoes