{{Short description|Volcano in Costa Rica}} {{redirect|Miravalles}} {{Infobox mountain | name = Miravalles Volcano | image = Miravalles volcano.jpg | image_caption = Miravalles Volcano in 1988 | elevation_m = 2028 | elevation_ref = <ref name=gvp>{{cite gvp|vn=345030|name=Miravalles|accessdate=11 March 2010}}</ref> | prominence_m = | prominence_ref= | map = Costa Rica | label_position = left | listing = List of volcanoes in Costa Rica | location = Costa Rica | range = Cordillera de Guanacaste | coordinates = {{coord|10|44|54|N|85|09|10|W|type:mountain_scale:100000|format=dms|display=inline,title}} | coordinates_ref = <ref name=gvp/> | topo = | type = Stratovolcano | age = 1.5 Myr | volcanic_arc = Central America Volcanic Arc | last_eruption = September 1946<ref name=gvp/> | first_ascent = | easiest_route = }}
The '''Miravalles Volcano''' is an andesitic stratovolcano<ref name=gvp/> within the Miravalles Protected Zone,<ref>{{cite web |url=https://www.sinac.go.cr/EN-US/ac/acat/Maps/Z20_Miravalles.jpg |title=Zona Protectora Miravalles --- 11672 ha |publisher=Ministry of Environment and Energy (Costa Rica) |accessdate=17 May 2026}}</ref> a nature reserve in Costa Rica. The Miravalles Volcano reaches an elevation of {{convert|2028|m}} and is the tallest volcano in the Cordillera de Guanacaste mountain range.<ref>{{cite book |title= Costa Rica |url= https://archive.org/details/costarica0000fire |url-access= registration |last= Firestone |first= Matthew |author2=Wendy Yanagihara |author3=Mara Vorhees |year= 2008 |publisher= Lonely Planet |location= London |edition= 8th |isbn= 978-1-74104-885-8 |page= [https://archive.org/details/costarica0000fire/page/206 206] }}</ref> It is the site of the most developed and productive geothermal field in Costa Rica,<ref name=gvp/> with a plant capable of generating 161.5<ref name=TGE/> or 162.7 MW of power.<ref name=PT/><ref>{{cite web|last=Stater|first=Adam|title=The Miravalles Volcano|url=http://www.anywherecostarica.com/attractions/national-park/tenorio-volcano}}</ref>
==Geology== Miravalles is one of five post-caldera cones within the {{convert|15|by|20|km|adj=on}} Guayapo caldera, the latter formed between about 1.5 and 0.6 million years ago.<ref name=gvp/> There are two andistic lava flows on its northern flank, one descending west towards a geothermal power plant (see section below), the other to the north into the Guayapo caldera.<ref name=Bergo>{{cite book |url=https://www.google.ca/books/edition/Geomorphology_and_Volcanology_of_Costa_R/L8_8DAAAQBAJ?hl=en&gbpv=1&dq=%22Miravalles+Volcano%22&pg=PA162&printsec=frontcover |title=Geomorphology and Volcanology of Costa Rica |first=Jean Pierre |last=Bergoeing |publisher=Elsevier |year=2017 |pages=162-163 |isbn=978-0-12-812067-5 |accessdate=17 May 2026}}</ref> Lava flows also cover the western and southwestern flanks of the Miravalles complex.<ref name=gvp/> There are parasitic cones near the crater at altitudes of {{convert|5098|ft}}, {{convert|5059|ft}} and {{convert|3280|ft}}.<ref name=Bergo/> Twin cones named Cerro la Giganta stand at {{convert|4888|ft}}.<ref name=Bergo/> On the southern face, there are three small cones, among them Gota de Agua at {{convert|3550|ft}} and Espiritu Santo at {{convert|3212|ft}}.<ref name=Bergo/>
The only reported historical eruptive activities are a small steam explosion on the south-western flank in 1946 and an erruption c. 5050 BCE.<ref name=gvp/>
==Geothermal power generation== In response to the 1973 and 1979 oil crises, Costa Rica, with little in the way of fossil fuel resources, began considering alternative energy sources.<ref name=DiPippo/> The ''Instituto Costarricense de Electricidad'' (Costa Rican Institute of Electricity, ICE) conducted an evaluation of the country's geothermal resources between November 1987 and October 1988; Miravalles was selected as one of three high-priority areas.<ref>{{cite pdf |url=https://gogn.orkustofnun.is/unu-gtp-report/UNU-GTP-1990-07.pdf |title=Gravity and Magnetic Assessment of the Tenorio Area, Costa Rica |author=Dagoberto Herrera Cabezas |year=1990 |page=6 |accessdate=17 May 2026}}</ref> Three deep exploratory wells were dug from 1979 to 1980; they all indicated that there was a "liquid-dominated reservoir" covering {{convert|15|km2}} under the volcano's southwestern slope.<ref name=DiPippo>{{cite book |url=https://www.google.ca/books/edition/Geothermal_Power_Plants/U9TRQp_empgC?hl=en&gbpv=1&dq=%22Miravalles+Volcano%22&pg=PA332&printsec=frontcover |title=Geothermal Power Plants |first=Ronald |last=DiPippo |edition=Third |publisher=Butterworth-Heinemanne |year=2012 |pages=332-334 |isbn=978-0-08-098206-9 |accessdate=17 May 2026}}</ref> Six more wells were dug between 1984 to 1986, followed by 20 more.<ref name=DiPippo/>
A hybrid power plant was constructed and commissioned in March 1994, with a capacity of 161.5<ref name=TGE>{{cite pdf |url=https://www.thinkgeoenergy.com/wp-content/uploads/2021/05/Costa-Rica-short.pdf |title=Costa Rica Geothermal Energy Market Overview |date=April 2021 |publisher=ThinkGeoEnergy |page=3 |accessdate=17 May 2026}}</ref> or 162.7 megawatts.<ref name=PT>{{cite web |url=https://www.power-technology.com/data-insights/power-plant-profile-miravalles-costa-rica/?cf-view |title=Power plant profile: Miravalles, Costa Rica |date=21 October 2024 |website=power-technology.com |accessdate=17 May 2026}}</ref> There are five power plants in four powerhouses, {{convert|48.5|km}} of pipelines and a total of 61 wells, consisting of production, injection and observation wells.<ref name=TGE/> A {{convert|50|km|adj=on}} power line connects it to the main electrical transmission line.<ref name=PT/> It is the most developed and productive geothermal field in the country, though it has reached its extraction rate ceiling.<ref name=TGE/> It is owned by ICE.<ref name=PT/>
== References == {{reflist}}
{{Volcanoes of Costa Rica}} {{Mountains of Costa Rica}} {{Central American volcanoes}}
Category:Active volcanoes Category:Stratovolcanoes of Costa Rica Category:Calderas of Central America Category:Mountains of Costa Rica Category:Two-thousanders of North America