Where the Andes don’t have volcanoes

There are any between Southern Ecuador and Central Peru – this is the most plausible explanation.

 

 

The usual condition for what a volcano breaks out or erupts is under the Earth crust – the mantle (the second layer going to the core), that is basically melted rock or magma, find weak zones at the crust where it can emerge due to the high pressure expanding the liquid and gas fluids as well.

 

This can happen in places where the crust is literally cracked because of subduction or embedding of a tectonic plate beneath another. The phenomenon causes so much friction that melts all the matter, so this tends to seek where to emerge by. If it gets, it goes up until reaching the surface taking out through a new way or a previously open one. A volcanic eruption happens so.

 

In case of the Andes, although Nazca Plate subducts under the South American Plate, it doesn’t do like an only lineal block but at two contact points:

• The first, according to surveys, could be underneath Cauca Valley, Southern Colombia, what causes seismicity and volcanism in that country and Ecuador.
• The second is in the Peruvian-Chilean Pit, what causes similar phenomena in these countries plus Bolivia and Northern Argentina.

 

“The volcanic activity only happens in southern Peru,” Peru’s Geophysical Institute (IGP, as its initials in Spanish) chairman Hernando Tavera stressed. IGP is the official agency monitoring Peruvian volcanoes and issuing warnings in case of volcanic crisis.

 

The Ecuadorian Southern (from the latitude of Gulf of Guayaquil, Guayas Province) and Northern & Central Peru are not contact zones amid the subduction phenomenon. In consequence, the volcanic eruptions are non-existent and improbable. Although, there are indeed other volcanism evidences like the hot springs – the most famous is Baños del Inca (Inca’s Hot Springs), just at the south of Cajamarca Metropolitan Area, Peru.

 

 

A matter of angle

According to a study by Hernando Tavera and yanet Antayhua, published for IGP in 2003, Nazca Plate abducts South American Plate at Northern & Central Peru in a 25-degree (of 90) angle until a 62-mile depth. From that point, the phenomenon does practically in a landscape way until 435 to 466 miles to the east of Peruvian-Chilean Pit (that is almost 5 miles depth).

 

According to Ecuador’s National Poli-technical School (EPN, as its initials in Spanish), speaking about the south of that country, the subduction phenomenon didn’t allow more magma to surface. In consequence, the volcanoes are also non-existent in that portion of the country. At least, the ones those should appear in the Quaternary Period – 2.5 million years ago, in other words.

 

 

It doesn’t happen… but it already happened

According to University of Chile, the Andean Range began to form 800 million years ago because a combination of sinking/raising phenomena that, as we said before, continue mostly active at Colombian Southern and Peruvian Southern.

 

nevertheless, Ecuadorian Southern and Peruvian Northern & Midland actually have evidences of former volcanism. Returning to Southern Ecuador, according to EPN, that might happen 1 million years ago at least. And the evidences seem to be around Cuenca, the capital city of Azuay Province.

 

In the case of Northern and Central Peru, that might happen 8 million years ago if we base straight upon the study of Tavera & Antayhua. One of the evidences could be White Range (Ancash Department), that groups the highest summits of Peru. But, diverse sources clarify those mountains, covered by glaciers now, are not volcanoes.

 

Diverse mineralogic studies at Peruvian Northern & Midland support that many deposits, like Tambograndé, Piura, have volcanic origin. In fact, across a north-south central strip of this department, the Lanconés-Ereo Batholith (massive surfacing of rock) runs along. It had a volcanic origin. It had. The volcanism ceased ten of million years ago at least.

 

According to Peru’s Geological, Mineral, Metallurgic Institute, the Tambograndé deposit could form because of volcanism ending the Mesozoic Era – 66 million years ago at least. At the moment, specialist explain the possibility of a volcano where the Andes have none may happen… but up to millions of years. Anyway, we are aware.

 

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