Editing Shield volcano (section)

=== Galápagos Islands ===
The [[Galápagos Islands]] are an isolated set of volcanoes, consisting of shield volcanoes and lava plateaus, about {{convert|1100|km|mi|abbr=on}} west of Ecuador. They are driven by the [[Galápagos hotspot]], and are between approximately 4.2&nbsp;million and 700,000 years of age.<ref name=uoo-galapagos/> The largest island, [[Isabela Island (Galápagos)|Isabela]], consists of six coalesced shield volcanoes, each delineated by a large summit caldera. [[Española Island|Española]], the oldest island, and [[Fernandina Island|Fernandina]], the youngest, are also shield volcanoes, as are most of the other islands in the chain.<ref name="hvw">{{cite web|title=How Volcanoes Work: Galapagos Shield Volcanoes|url=http://www.geology.sdsu.edu/how_volcanoes_work/Thumblinks/Galapagos_page.html|publisher=San Diego State University|access-date=22 February 2011|archive-date=3 December 2010|archive-url=https://web.archive.org/web/20101203205121/http://www.geology.sdsu.edu/how_volcanoes_work/Thumblinks/Galapagos_page.html|url-status=dead}}</ref><ref>{{cite web |url=http://www.galapagosonline.com/Galapagos_Natural_History/Geology/Volcanoes.html |archive-url=https://web.archive.org/web/20010723104558/http://galapagosonline.com/Galapagos_Natural_History/Geology/Volcanoes.html |url-status=dead |archive-date=23 July 2001 |title=Volcanoes |publisher=Galapagos Online Tours and Cruises |access-date=22 February 2011 }}</ref><ref name="vsa">{{cite web|title=Volcanoes of South America: Galápagos Islands|url=http://www.volcano.si.edu/world/region.cfm?rnum=1503|work=[[Global Volcanism Program]]|publisher=Smithsonian National Museum of Natural History|access-date=22 February 2011}}</ref> The Galápagos Islands are perched on a large lava plateau known as the Galápagos Platform. This platform creates a shallow water depth of {{convert|360|to|900|m|ft|0|abbr=on}} at the base of the islands, which stretch over a {{convert|174|mi|km|0|abbr=on}} diameter.<ref name=uog /> Since [[Charles Darwin]]'s visit to the islands in 1835 during the [[Second voyage of HMS Beagle|second voyage of HMS ''Beagle'']], there have been over 60 recorded eruptions in the islands, from six different shield volcanoes.<ref name="hvw" /><ref name="vsa" /> Of the 21 emergent volcanoes, 13 are considered active.<ref name=uoo-galapagos>{{cite web|title=Volcanic Galapagos: Formation of an Oceanic Archipelago|url=http://darkwing.uoregon.edu/~drt/Research/Volcanic%20Galapagos/presentation.view@_id=9889959127044&_page=0&_part=0&.html|publisher=University of Oregon|access-date=23 February 2011|author1=Bill White  |author2=Bree Burdick |name-list-style=amp }}</ref>

[[Cerro Azul (Ecuador volcano)|Cerro Azul]] is a shield volcano on the southwestern part of Isabela Island and is one of the most active in the Galapagos, with the last eruption between May and June 2008.  The Geophysics Institute at the [[National Polytechnic School (Ecuador)|National Polytechnic School]] in [[Quito]] houses an international team of [[seismology|seismologists]] and [[volcanologist]]s<ref>[http://www.igepn.edu.ec/  Institute for Geophysics at National Polytechnic School   ]</ref> whose responsibility is to monitor Ecuador's numerous active volcanoes in the Andean Volcanic Belt and the Galapagos Islands.  [[La Cumbre (Galápagos Islands)|La Cumbre]] is an active shield volcano on Fernandina Island that has been erupting since April 11, 2009.<ref>{{cite web|title=Galapagos volcano erupts, could threaten wildlife|url=https://news.yahoo.com/s/ap/20090412/ap_on_re_la_am_ca/lt_ecuador_galapagos_volcano|archive-url=https://web.archive.org/web/20090415162111/http://news.yahoo.com/s/ap/20090412/ap_on_re_la_am_ca/lt_ecuador_galapagos_volcano|archive-date=2009-04-15|date=October 22, 2015}}</ref>

The Galápagos islands are geologically young for such a big chain, and the pattern of their rift zones follows one of two trends, one north-northwest, and one east–west. The composition of the lavas of the Galápagos shields are strikingly similar to those of the Hawaiian volcanoes. Curiously, they do not form the same volcanic "line" associated with most hotspots. They are not alone in this regard; the [[Cobb–Eickelberg Seamount chain]] in the North Pacific is another example of such a delineated chain. In addition, there is no clear pattern of age between the volcanoes, suggesting a complicated, irregular pattern of creation. How the islands were formed remains a geological mystery, although several theories have been proposed.<ref name=usgs-galapagos>{{cite journal|last=Bailey|first=K.|title=Potassium-Argon Ages from the Galapagos Islands|journal=[[Science (journal)|Science]]|date=30 April 1976|volume=192|issue=4238|pages=465–467|doi=10.1126/science.192.4238.465|bibcode = 1976Sci...192..465B|pmid=17731085|s2cid=11848528}}</ref>