Sangay

Sangay
Quechua
Pronunciation	[saŋˈɡaj][needs Quechua IPA]
Geography
Sangay Location of Sangay in Ecuador
Location	North Volcanic Zone
Last eruption	1934 to 2024 (ongoing)[6]
Climbing
First ascent	4 August 1929[5]
Easiest route	Rock/Snow climb[7]

Sangay (also known as Macas, Sanagay, or Sangai)

Folklore sourced from native people in the region compared Sangay to a lighthouse surrounded by a sea, which represented the dense jungle. The density of the jungle caused people to lose their way, but seeing ash and steam emissions from the volcano would help orient travelers along their way. Scientists have interpreted folklore like this as evidence of frequent and long-lasting eruptive activity at Sangay.[9]

In January 2024, archaeologists announced the discovery of archaeological sites on the east side of the volcano known as the Upano Valley sites. It is estimated that this cluster of urban settlements were inhabited between about 500 BCE to sometime between 300 and 600 CE. Altogether the cities may have reached a population between 15,000 and 100,000 people. They were surrounded by agricultural fields that archaeologist Stéphen Rostain speculates may have been particularly productive because their proximity to Sangay.^[10][11]

Seventeen additional archaeological sites had been located prior to the 2024 announcement including potential monuments. An estimated 30,000 people lived in the region before Spanish occupation began in 1534. The Spanish prospected for gold on and around the volcano through the 16th and 17th Centuries and settled the area but expeditions undertaken in the 19th Century noted no inhabitants nearby. Modern development of the eastern side of the volcano began in the early 20th Century.^[12]

The volcano and lands surrounding it were placed in a National Wildlife Reserve by the Ecuadorian government in 1975. This became Sangay National Park in 1979, which was expanded in 1992. The United Nations added it to their list of World Heritage Sites in 1983. From 1992 to 2005, poaching and human development led the UN to consider the site as being endangered but removed this status in 2005.^[12]

The modern native inhabitants of the region primarily consist of Quechua people.^[12] The name Sangay comes from the Quechuan languages and is translated as "the frightener."^[5]

Geography

Sangay is on the eastern edge of the Andes Mountains in central Ecuador about 160 km (99 mi) south of

Sangay reaches high enough to enjoy snow cover on its upper slopes despite its location near the Equator. It is disputed whether or not the volcano has a glacier though ice and snowfields are present.^[13][14] The snow line in this part of South America lies approximately 4,800 m (15,700 ft) above sea level.^[12]

The mountain environment leads to significant changes in precipitation across short distances. Prevailing winds are out of the east, causing rainfall to be greatest to the east where moisture is sourced from the Amazon rainforest.^[15] Observed rainfall averages from 4,827 mm (190.0 in) per year at Pastaza to the northeast of the volcano to 423 mm (16.7 in) at Riobamba just 20 km (12 mi) west of the summit in the rain shadow.^[16] Orographic lift and the Intertropical Convergence Zone are major factors in precipitation values.^[12]

Annual temperatures see little variability but diurnal changes in temperature can be wide in more arid portions of the mountain's slopes. Higher elevations never rise above 0 °C (32 °F).^[12] Climate change threatens the snowpack and the high altitude grasslands.^[14]

Geology

Regional setting

The next active volcano in the chain, Sabancaya, is in Peru, 1,600 km (990 mi) to the south. Sangay is above a seismogenic tectonic slab about 130 km (80 mi) beneath Sabancaya, reflecting a sharp difference in the thermal character of the subducted oceanic crust, between older rock beneath southern Ecuador and Peru (dated more than 32 million years old), and younger rock under northern Ecuador and Colombia (dated less than 22 million years old). The older southern rock is more thermally stable than the northern rock, and to this is attributed the long break in volcanic activity in the Andes; Sangay occupies a position at the boundary between these two bodies, accounting for its high level of activity.^[17]

Formation

Sangay developed in three distinct phases. Its oldest edifice, formed between 500,000 and 250,000 years ago, is evidenced today by a wide scattering of material opening to the east, defined by a crest about 4,000 m (13,120 ft) high, pockmarked by secondary ridges; it is thought to have been 15–16 km (9–10 mi) in diameter, with a summit 2 to 3 km (1 to 2 mi) southeast of the present summit. The curved shape of the remnants of this first structure shows that it suffered a massive flank collapse, scattering the nearby forest lowlands with debris and causing a large part of its southern caldera wall to slide off the mountain, forming an

Sangay

Tungurahua

Quilotoa

Cotopaxi

Illiniza

Antisana

Pichincha

Reventador

Cayambe

Chimborazo

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Major volcanoes in Ecuador

Sangay's second edifice began to form anew after the massive sector collapse that damaged the first, being constructed between 100,000 and 50,000 years ago. Remnants of its second structure are within the southern and eastern parts of the debris from its first collapse; some remnants of the volcano lie to the west and north as well. Sangay's second structure is believed to have had an east-to-west elongated summit, and like its first summit structure, it suffered a catastrophic collapse that created a debris avalanche 5 km (3 mi) wide and up to 20 km (12 mi) in length. It was likely less voluminous than the volcano's first version, and its summit lay near Sangay's current summit.^[17]

Recent activity

Sangay currently forms an almost perfect

The current phase of the ongoing eruption began on 26 March 2019,^[21] and it has remained in continuing eruption status (intermittent eruptive events without a break of 3 months or more) as of January 2024.^[22]

On 15 June 2022, the United States' National Weather Service issued an ashfall advisory as the volcano went into a state of unrest, producing a plume of volcanic ash. Mariners traveling in the vicinity were cautioned about the possibility of debris.^[23][24]

Ecology

Sangay is one of two active volcanoes in the Sangay National Park, the other being Tungurahua to the north. As such it has been listed as a UNESCO World Heritage Site since 1983. The area's isolation has allowed it to maintain a pristine ecology relatively untouched by human interaction, and the park hosts a biome ranging from alpine glaciers on the volcanoes' peaks to tropical forest on their flanks. Altitude and rainfall are the most significant local factors affecting fauna, and therefore the lushest ecosystems are found on the wetter parts of the volcano's eastern slope.^[25]

The highest level below the snowline is dominated by