The 4,064 m Volcan Tacana straddles the Mexico – Guatemala border in the far SE corner of Mexico.  It is both the farthest S of all volcanoes in Mexico and at the very NW end of the Central America Volcanic Arc that stretches SE from it. 

The volcano itself is a composite stratovolcano that rises 1,800 m above the surrounding terrain.  Eruptive products are typically andesites, basaltic andesites, trachyandesites and basaltic trachyandesites.  Tacana is the tallest of an extensive volcanic system built on three large calderas breached to the S.  The summit has a line of lava domes.  There is a satellite vent, San Antonio on the SW flank.  It has a small dome in its crater. 

The volcano has multiple lava flows on its N and S flanks.  it is surrounded by lahar and debris avalanche deposits in many of its surrounding valleys. 

The immediate area is reasonably remote, with 21,000 within 10 km, though the population farther out gets dense, with nearly 600,000 within 30 km, and 4.5 million within 100 km.  Most of the immediate population is located on the coastal plains SW of the volcano.  The largest urban area is centered around Quetzaltenango, 72 km SE.

Tapachula is the largest city close to Tacana, 31 km SW, with a population near 354,000.  Economy of Tapachula is varied, with agriculture, livestock, mining and manufacturing.  There is a growing export sector and a major port on the Pacific Coast 25 km SW.  Tourism is a growing sector.  Climate varies from hot near the coast to temperate at high elevations.  Climbers on Tacana are warned against cold when climbing the 4,064 m volcano.  Average temperatures range 34° – 20° C.  Average rainfall is nearly 220 cm/year.  Given multiple rivers draining the mountains into the floodplain, flooding is a real problem due to regular hurricanes. 

Tacana is surrounded by the 64 km2 Volcan Tacana UNESCO Biosphere Reserve created in 2006.  It is a popular target for climbers and hikers. 

Robert Hopkins was a tourist who climbed Tacana sometime before 2017.  He thought it would be a relatively easy climb, though the climbing world lists it as a 16 km trip.  People generally climb to the top, overnight, and descend after watching sunrise.  The problem with doing this is that it gets quite cold on the top, near freezing with a wind.  His day trip turned into a rather harrowing two-day unplanned adventure where everything that could go wrong went wrong.  His 2017 book Lost on the Volcano Tacana details the adventure. 

As of 2021, there were four active seismometers, a camera and a meteo station dedicated to Tacana.  Looks like Universidad de Ciencias y Artes de Chiapas has the responsibility for monitoring Tacana.  I can find no dedicated webcam for Tacana, though there are webcams available in Tapachula and Quetzaltenango. 

Region

Tacana is located at the NW end of the Central American Volcanic Arc.  Volcanoes to the SE of it along the arc are closely spaced and recently active.  NW into Mexico there is a 650 km break in volcanic activity until you arrive at the Trans Mexican Volcanic Belt.  Therea are only a few volcanic features in this region, El Chichon, 275 km NNW from Tacana and the Chiapanecan Volcanic Arc, some 130 km N. 

The Chiapanecan Volcanic Arc is a 150 km stretch of volcanic structures aligned generally NW – SE.  There are at least 10 volcanic structures associated with it, including seven domes, one explosion crater, one collapse structure and one dome complex.  A few papers include El Chichon, another 120 km N as part of this arc.  Both El Chichon and the Chiapanecan Volcanic Arc will be subjects of future posts.

A review of volcanoes in the neighborhood of Tacana will be limited to those within 100 km or so.  All distances will be measured from the Tacana summit.

Mispia  

The Mispia volcanic dome is nearly the southernmost volcanic feature in the Chiapanecan Volcanic Arc, 151 km NNW from Tacana, well into S Mexico.  It rises 600 m above the surrounding base and is around 3.6 km in diameter.  There are some block and ash flows extending 6.8 km to the SE.  Average flow depth is 6 m.  These cover around 32 km2.  Blocks are dome rock in a sandy matrix. 

Tajumulco

Tajumulco is the highest volcano in Central America at 4,203 m.  It is topped with two summits.  One of these has a small 50 – 70 m crater.  Lava flows from the summit traveled down a deep valley on the NW flank.  It erupts andesites – dacites.  There are multiple reports of historic eruptions.  Sapper in 1917 considered it to have erupted in historic times but did not have accurate dates. 

The volcano was reported to have erupted in 1765, ejecting rocks that destroyed neighboring houses.  This report may have been of a rock avalanche.  There are multiple unconfirmed reports of eruptions, some of them before 1808, 1863 and 1893. 

The area surrounding the volcano is sparsely populated, with the nearest town 14 km SE.  It is infrequently visited, though can be climbed.  What should be an excellent view is frequently obscured by clouds. 

Siete Orejas

Siete Orejas is located in Guatemala, some 63 SE of Tacana.  We briefly discussed it in our Jul 2020 Almolonga and Quemado post. 

Santa Maria / Santiaguito

Santa Maria / Santiaguito is located 73 km SE from Tacana.  We discussed it in our May 2016 Continuing Eruptions at Santiaguito post. 

Almolonga

Almolonga is located some 74 km SE from Tacana.  We discussed it in our Jul 2020 Almolonga and Quemado post. 

Cuxliquel

Cuxliquel is a recent dome complex in the center of a semi-circular depression of unknown origin.  It is located 81 km ESE from Tacana.  Much of the depression is filled with thick pyroclastics from the Los Chocoyos Ash, the 84 ka eruption of the Atitlan caldera to the SE.  There is a Mayan altar at the summit of the main Cuxliquel dome and it is considered sacred to the indigenous Kiche. 

Santo Tomas (Pecul)

Santo Tomas is located some 83 km SE from Tacana.  It is one of six recently active volcanoes surrounding Quetzltenango.  These include Santa Maria / Santiaguito, Cerro Quermado, Zunil and Siete Orejas.  We briefly touched on Santo Tomas (Pecul) in our Jul 2020 Almolonga and Quernado and our May 2016 Santiaguito posts. 

Tacana Volcanic Complex

The Tacana Volcanic Complex is formed by four coalescing volcanic edifices along a NE trend.  These are Chichuj, 3.800 m, Tacana, 4,060 m, Las Ardillas dome complex, 3,782 m.  The fourth and youngest is San Antonio, 3,700 m.  The last three eruptions at the complex took place near the summit of Tacana 1881, 1949 and 1986.  The 1986 phreatic eruption took place on the N slope of the complex. 

This system has a complex history with three calderas, four volcanic edifices, multiple eruptions and flank collapse / debris avalanche events.  Even the timing of caldera events aren’t linear, with two of them being active simultaneously, like the active vents of Tacana, San Antonio and the Sibinal Caldera.  Sorting all this activity out is not unlike trying to untangle individual strings of spaghetti.  We will try to describe what we think happened at the top level before going into it in more detail later. 

The sequence of events across all systems seems to be initial eruptions of andesite lava flows followed by dome building.  Domes were unstable, collapsing with pyroclastic block and ash flows.  Somewhere along the line, there were flank collapse and debris avalanche events followed by subsequent dome extrusion and / or lava flows until the cycle began anew.  There were multiple Plinian eruptions starting at the end of the lava flow series of eruptions. 

Initial activity at Tacana 225 ka erupted lavas and built the Chichuj volcano.  This formed a main cone topped with a lava dome.  This cone suffered a flank collapse / debris flow to the W.  Subsequent activity built Tacana starting 50 – 40 ka to the W of Chichuj.  Eruptions produced lavas and built a semi-conical summit.  Activity at the third volcano, San Antonio started 20 ka SW of Tacana.  It once again started with lava flows and ended up with a summit dome.  Tacana and San Antonio were active simultaneously until San Antonio was partly destroyed by a lateral blast eruption 50 AD.  This left a horseshoe shaped crater partly refilled with lava flows and a dome afterwards.  Fumaroles and intense hydrothermal alteration persist on its N flank.  The Plan de Ardillas lava dome between Tacani and San Antonio is undated but thought to be active around the same time. 

Calderas

The Tacana Volcanic Complex is built in three caldera structures aligned generally E – W.  The central caldera complex, San Rafael, has been mostly filled with the four volcanic structures of the Tacana volcanic complex.  Neighboring Sibinal to the E has also been recently active.  Activity at Chanjale, on the W portion of the complex, mostly ended. 

The oldest of these is San Rafael, a 9 km diameter structure dating around 2 Ma.  It probably began as an andesitic stratovolcano initially erupting lava flows followed by domes.  The domes were destroyed by generating block and ash flows around 1.76 Ma.  Evolution of this stratovolcano / caldera is probably more complex but no detailed studies are done yet. 

It exposes a 200 m ignimbrite found at 1,600 m.  The ignimbrite is surrounded by lithics, andesites and pumice fragments.  A thick sequence of 20 m thick andesite lava flows cover the N rim.  In places, the lava flows are covered by block and ash flows.  There is a thick debris avalanche ponded inside the caldera walls.  It is much younger than the ignimbrite or lavas. 

The 1 Ma Chanjale caldera is located on the W portion of the complex.  It is 6.5 km wide and open to the E.  The caldera is cut by the Coatan River.  The rim is constructed of several units of lavas, pyroclastics and debris flows.  Lava thicknesses are up to 200 m in places.  There is a white ignimbrite and pyroclastics on the S flank.  The sequence is topped by debris flow deposits up to 12 m thick.  Activity here stopped first.

The Sibinal caldera is the most recent of these, located at the E end of the string.  It is the smallest at around 5 km in diameter.  The caldera wall exposes mostly andesite lava flows overlying basement rock.   The youngest unit of this complex is an apron of debris flow deposits interbedded with at least three fall deposits.  One of these is the Sibinal Pumice dating 32 ka.  There is no ignimbrite associated with Sibinal, so the caldera structure may be due to a series of gravitational collapses. 

Chichuj

Chichuj is a semi conical stratovolcano with a 1.1 km summit crater and lava dome.  It tops out at 3,800 m.  The W flank has a flank collapse scar that is filled with the younger Tacana.  Early activity erupted andesite lavas that extend as much as 4 km from the present crater rim.  This was followed by extrusion of domes which were destroyed by a series of explosive eruptions that created pyroclastic flows.  Activity switched back to effusive with several lava flows.

Oldest dated deposits are a series of block and ash flows and volcaniclastic deposits S and SW of the present summit.  They are thick at over 100 m forming a thick downslope fan.  There are multiple flow units with dacite blocks embedded in a medium dacite ash matrix.  There is a 20 m thick debris flow.  One of the embedded blocks dates to 225 ka.  Lava flows after the dome building cycle resumed.  The oldest of these dates is 142 ka. 

Construction of the cone was disrupted by at least three flank collapse events.  The largest of these was to the W.  It left no visible deposits as it was covered by the younger Tacana material.  Avalanche deposits to the SE and NE were minor collapses from the summit.  The initial flank collapse to the W removed perhaps half of the 30 km3 volume of the original Chichul volcano.  Deposits are likely buried by younger volcanoes and their eruptive products. 

The Muxbal debris avalanche on the SE flank is covered by a block and ash flow from neighboring Tacana dating 28 ka.  The Muxbal deposit to the SE consists of meter-sized blocks in an ash matrix.  The matrix is hydrothermally altered.  There are no associated pyroclastics with this flow, suggesting it was a cold, gravity collapse of altered materials.  The debris flow is covered by a sequence of lake sediments and erosion deposits. 

The 24.6 ka La Vega debris avalanche to the NE has larger blocks, up to 4 m.  It is covered by a massive scoria which is in turn covered by fine lapilli to coarse ash.  The scoria beds probably came from a pyroclastic flow from a weak, collapsing column. 

Activity following the flank collapses continued with extrusion of a summit dome, explosions, dome collapse and pyroclastic block and ash flows. 

Part 2 of this post will discuss the Tacana volcano, San Antonio and Plan de Las Artillas in greater detail.  it will also include eruptions, tectonics and conclusions.  

Additional information

Smithsonian GVP – Tacana

Late Holocene Pelean-style eruption of Tacana volcano, Mexico and Guatemala:  past, present and future hazards, Martin, et al, Geological Society of America Bulletin, 2000

Tacana volcano, Guatemala / Mexico, Volcano number 1401-13

Tephra fallout hazard assessment at Tacana volcano (Mexico), Vazquez, et al, Apr 2019

Study area – The watersheds of the Tacana volcano, Freie Universitat Berlin

Eruptive history of the Tacana volcanic complex, Macias, et al, Feb 2015

Geological evolution of the Tacana volcanic complex, Mexico – Guatemala, Garcia-Palomo, et al, Jan 2006

Risk management of El Chichon and Tacana volcanoes:  Lesons learned from past volcanic crises:  Chapter 8, De la Cruz-Reyna and Tilling, 2015

Active volcanoes of Chipas (Mexico):  El CHichon and Tacana, Solamacchia & Macias, Editors, Oct 2016

The ~14 ka Plinian-type eruption at the Tacana volcanic complex, Mexico Guatemala, Arce, et al, Dec 2008

Late formative flooding of Izapa after an eruption at Tacana volcano, Macias, et al, Sept 2018

Petrology and geochemistry of the Tacana volcanic complex, Mexico – Guatemala:  evidence for the last 40,000 yr of activity, Mora, et al, Jan 2003

Evidence of volcanic activity in the growth rings of trees in the Tacana volcano, Mexico-Guatemala, Allende, et al, Sept 2019

Volcaniclastic sequences at the foot of Tacana volcano, southern Mexico:  Implications for hazard assessment, Murcia & Macias, Jul 2014

New chronological constraints on intense Holocene eruptions and landslide activity at Tacana volcanic complex (Mexico), Alcala-Reygosa, et al, May 2021

Chemical and isotopic compositions of thermal springs, fumaroles and bubbling gasses at Tacana volcano (Mexico-Guatemala):  implications for volcanic surveillance, Rouwet, et al

The analysis of the seismic Tacana volcanic complex in 2017 – 2018, AYA Pacheco, 2023

Petrogenetic and tectonic implications of major and trace element and radiogenic isotope geochemistry of Pliocene to Holocene rocks from the Tacana volcanic complex and Chiapanecan volcanic belt, southern Mexico, Verma & Verma, May 2018