Native name: Isla Socorro | |
|---|---|
 Socorro Island, from satellite image | |
 | |
  Socorro Location in Mexico | |
| Geography | |
| Location | Pacific Ocean |
| Coordinates | 18°47′04″N110°58′30″W / 18.78444°N 110.97500°W /18.78444; -110.97500 |
| Archipelago | Revillagigedo Islands |
| Area | 132 km2 (51 sq mi) |
| Length | 16.5 km (10.25 mi) |
| Width | 11.5 km (7.15 mi) |
| Highest elevation | 1,150 m (3770 ft) |
| Highest point | Mount (Cerro) Evermann |
| Administration | |
| State |  Colima |
| Demographics | |
| Population | 250 |
| Pop. density | 0.34/km2 (0.88/sq mi) |
Socorro Island (Spanish:Isla Socorro) is avolcanic island in theRevillagigedo Islands, aMexican possession lying 600 kilometres (370 mi) off the country's western coast. The size is 16.5 by 11.5 km (10.3 by 7.1 mi), with an area of 132 km2 (51 sq mi). It is the largest of the four islands of the Revillagigedo Archipelago.[1] The last eruption was in 1993.
The island rises abruptly from the sea to 1,050 meters (3,440 feet) in elevation at its summit. Socorro Island is the emerged summit of a massive, predominantly submarineshield volcano.
The island is part of the northern Mathematicians Ridge, amid-ocean ridge that became largely inactive 3.5 million years ago when activity moved to theEast Pacific Rise. All four islands along with the manyseamounts on the ridge are post-abandonment alkaline volcanoes. Socorro Island is unusual in that it is the only dominantlysilicicperalkaline volcanic island in the Pacific Ocean.[2]
It most recently erupted in late January and early February 1993, which was a submarine flank eruption off the coast from Punta Tosca.[3] An earlier eruption was on May 21, 1951; earlier eruptions probably occurred in 1905, 1896 and 1848. The initial volcanic event probably occurred in 3090 BC ±500 years.[4] Mount Evermann (Spanish:Cerro Evermann) is the name given to the summit dome complex, in honor ofichthyologistBarton Warren Evermann. The island's surface is broken by furrows, small craters, and numerous ravines, and covered inlava domes,lava flows andcinder cones.[5]
There are eight bays surrounding Socorro: three on the southern end of island – Vargas Lozano, Braithwaite, and Lucio Gallardo Pavon; Ensenada Grayson on the southwest; Blanca on the northwest with two inlets separated by a rocky outcropping; and North Bay on the island's north end with two inlets separated by a volcanic formation.[6]
There is a naval station, established in 1957, with a population of 250[7] (staff and families), living in a village with a church, that stands on the western side of Bahía Vargas Lozano, a small cove with a rocky beach, about 800 meters (870 yards) east of Cabo Regla, the southernmost point of the island. The station is served by a dock, a local helipad and Isla Socorro airport, located six kilometers to the north. There is a fresh water spring about 5 kilometers (3.1 miles) northwest of Cabo Regla, at the shoreline of Ensenada Grayson (or Caleta Grayson). This isbrackish and sometimes covered by the sea at high tide. In the 1950s, a small freshwater seep was known to exist some 45 meters (49 yards) inland at Bahía Lucio Gallardo Pavon (Binner's Cove), 800 meters (870 yards) northwest of the naval station.[8]
No evidence of human habitation on Socorro exists before its discovery by Spanish explorerHernando de Grijalva and his crew on 19 December 1533, who named itSanto Tomás[9][10] ("St Thomas Island";French:Isle St Thomas). In 1542,Ruy López de Villalobos, while exploring new routes across the Pacific, rediscoveredInocentes and renamed itIsla Anublada ("Cloudy Island") due to the clouds frequently forming on the northern slopes of Mount Evermann, and again in 1608,Martín Yañez de Armida, in charge of another expedition, visitedSanto Tomás and changed its name toIsla Socorro afterOur Lady of Perpetual Help (Virgen del Perpetuo Socorro).[11]
At the beginning of the twentieth century,Barton Warren Evermann, director of theCalifornia Academy of Sciences in San Francisco promoted the scientific exploration of the island. The most comprehensive biological collections were obtained at this time. The volcano on Socorro was renamed in his honor.
Archie Smith, an American laborer from San Diego, was marooned on the island for one month in 1929 before being rescued by a passing fishing boat. This was because the expedition that brought him to the island to shear wild sheep returned to port for supplies, but went bankrupt and could not return.[12]
In September 1997,Hurricane Linda passed near the island near peak intensity causing minor damage to meteorological instruments on the island.[13]
.jpg)
The lowlands of Socorro – except on the northern, morehumid side – are covered with thick shrubland, consisting mainly ofendemicCroton masonii and acactus, probablyEngelmann's prickly pear (Opuntia engelmannii). Above 650 metres (2,130 ft) and on the northern side, a richer vegetation occurs. This includes small trees such asFicuscotinifolia,black cherry (Prunus serotina[note 1]), and the endemicGuettardainsularis, which bearepiphyticorchids (Epidendrumnitens,E. rigidum and the endemicPleurothallisunguicallosa).[8]
The native landfauna isdepauperate, with birds predominating and mammals absent. There is one endemic species ofiguanid lizard (Urosaurus auriculatus) and theland crabJohngarthia oceanica, which also occurs onClipperton Island.[8][14]
Sheep, cats, androdents were introduced to the island by human activity; more recently, thelocustSchistocerca piceifrons has also established itself on the island.[15] Unlike the mammals onGuadalupe Island orClarión, their impact on the localflora was minor, butcat predation has had a drastic effect since the mid-1970s due to the fauna'sisland tameness,[8][16] and the locusts that swarm twice a year seriously damage vegetation during that time. There have been no recordedextinctions of plants on Socorro; several birds have been drastically affected by cat predation however, and onetaxon, theSocorro dove, has gone extinct in the wild.[17][18]
Socorro is an important breeding location for severalseabirds, many of which have here one of their north(east)ernmost breeding colonies. The present status of these birds is not well known, and they presumably have suffered from cat predation. In 1953, the following taxa were present:
Non-endemic landbirds andshorebirds occur mostly as vagrants or use the island as a stopover duringmigration; thenorthern mockingbird became established in the late 20th century.[15] Among those that are recorded not infrequently aregreat blue heron,Hudsonian curlew,spotted sandpiper andwandering tattler. Unlike the situation on smaller and more isolated Clarión, wind-blown or vagrant birds seem to constitute the bulk of the recorded species, includingbrown pelican,osprey,peregrine falcon,semipalmated plover,willet,sanderling,belted kingfisher andbuff-bellied pipit. It may be that this puzzling observation is due to the presence of thered-tailed hawks and cats, which has at least made the localUrosaurus more wary than its relative on Clarión, and might deter passing birds from stopping on Socorro.[8]
Being the largest of the Revillagigedo Islands and closer to mainland thanClarion, Socorro sports a rich array of endemictaxa, mainly plants and landbirds as well as lizards. Some are threatened due to the presence of feral cats.[19]
According toPlants of the World Online there are 21 species of plant that are strictly endemic to the island.[20]
In addition there are five more species that are endemic to the Revillagigedo Archipelago growing on both Socorro and one of the other islands.[20]
There are also an endemicvariety of paintbrush flower,Castilleja bryantii var.socorrensis, and asubspecies namedLepechinia hastata subsp.socorrensis in addition to other species that are native, but not endemic.[20]
Socorro Island is a popularscuba diving destination known for underwater encounters withdolphins,sharks,manta rays and otherpelagic animals. Divers visit here on live-aboard dive vessels. The most popular months are between November and May when the weather and seas are calmer. November to December are popular months to visit for a good chance to dive with whale sharks.[21] January and February are popular months to scuba dive with humpback whales as they are then migrating through the Revillagigedo archipelago.[citation needed]
| International | |
|---|---|
| Geographic | |
| Other | |
