While everybody is looking to the fiery Masaya lava lakes, Klyuchevskoy’s eruption stamina or Santiaguito’s massive ash production, I have also kept a wary eye on Ticsani. OVS is presenting reports fortnightly now, and, though the earthquake activity is decreasing at the moment, there has been a distinctive overall rise over the last decade or longer. Whatever the outlook, Ticsani is an interesting volcano, both to visit and to read about!
Ticsani volcano, locally also spelled Tixani, is a 5408-m-high, dacitic–andesitic lava dome complex located about 50 km behind the Central Volcanic Zone in Southern Peru, 60 km NE of the town of Moquegua. Around it there are three districts which are home to more than 10,000 people; they are at risk should this volcano ever decide to erupt. This to happen in the forseeable future is not altogether unrealistic, but you know what our wise scientists always say: the question is not IF, but WHEN…
Ticsani and its two neighbor volcanoes, Ubinas and Huaynaputina, are often seen as a single volcanic group because of their particular location outside the main volcanic zone, in the more complex environment of the major regional fault-systems: the main NW–SE strike-slip fault system, associated with the volcanic arc, and the N–S normal faults related to the Graben of Rio Tambo. The three volcanoes are systematically positioned around the graben structure at points of intersection with currently active NE–SW strike-slip faults. Geochemical characteristics suggest that the magmas of Ubinas, Huaynaputina and Ticsani evolved from a common reservoir situated at a depth between 20 and 30 km.
The OLD TICSANI (“Ticsani antiguo”) extends to the east and north of the “Modern Ticsani”-complex and occupies an area of 65 km². Volcaniclastic lavas and deposits are made up of trachytic-andesitic lavas, intercalated with volcaniclastic rocks (volcanic breccias and conglomerates) and to a lesser amount of ignimbrites; together they reach a thickness of more than 900 m. The volcano has been K-Ar dated to be 190 ka old.The calculated volume is 10.6 km³ of loosely layered rock fragments. The ancient edifice of Old Ticsani collapsed westward, pushing huge debris avalanche deposits as far as to the Rio Tambo valley with thicknesses ranging from 200 to 500 m.
MODERN TICSANI (“Ticsani moderno”) is sporting no less than three lava domes, roughly aligned in S-N direction, which have been named highly imaginatively as D1, D2 and D3. The domes are of an elongated to round-ish, cylindrical shape, 1.6 to 2 km long and have sidewalls up to 250m high. It also has three craters: The oldest, C1 is located east of the domes (Pampa Camaña). Today there is no more than a sandy indentation in the desert, it is entirely covered by gray to whitish gray pyroclastic deposits. The second is now occupied by dome D2 and only a part of the crater rim is still intact, wereas the third is completely covered by the overflowing lava dome D3.
D1 – This is the southernmost dome. Its emplacement was accompanied by explosive eruptions, dated to the middle Holocene.
D2 – A sub-Plinian and phreatomagmatic eruption followed ~10,600 years ago, overlaying these middle Holocene deposits with pumice and lava bombs. The D2 dome rose inside that old crater. Its lavas have angular surfaces and they are less weathered than in dome D1. D2 is covered by ashfall deposits “gray Ticsani”.
D3 – The dome D3 grew in the youngest crater and flowed down to the NW by gravity.
So the three domes show a migration towards N, very probably associated with a fracture or regional deep fault. However, following next in line to the north there is another round-ish structure that is much older again: marked on the geological map as a cryptodome from the late Pleistocene era, lying roughly in the middle of the Old Ticsani perimeter. As this is topographically in line with the three modern domes, it comes to my mind that the rising of this cryptodome could have been instrumental to the creation or extension of the said regional deep fault or fracture that is supposed to exist under the three domes.
Three being the magic number here, also 3 deposits of pyroclastic falls have been identified; they represent three explosive eruptions in the last 14.000 years: The first is the most important: pumice-lapilli fall “Ticsani gray”, linked to the sub-Plinian event ~10,600 BP. It covers approximately 806 km², forming an extensive desert to the E, SE and NE. The pumice is fibrous, of trachytic composition and whitish gray. The second is the ashfall “Ticsani gray” from a moderate eruption in between. The last eruption of the volcano Ticsani emplaced the third layer, “Ticsani brownish”. The date of this eruption is also not known, but the layer of this brown pumice helped scientist with an important discovery:
No evidence is found in chronicles and reports of Ticsani’s historical activity. However, when scientists detected that the pumice fall called “Ticsani brownish” is laid, in places, on top of the latest ash fall deposit from the nearby volcano Huaynaputina, it seemed to be proven that this pumice was blown out in historical times – after 1600 AD.
From the lower parts to the base of the domes there are several “steps” of lavas, formed from successive effusions. A topographic change shows at the boundary between the blocky lava and the three domes (between 4600 and 4700 m high). The degree of weathering, alteration (oxidation) and much heavier erosion of the lava blocks, suggest that these lavas belong to an effusive event earlier than the emplacement of the domes. It is possible that the centre of emission of these lavas was the C1 crater east of the domes.
This complex history is responsible for the highly asymmetric shape of Ticsani volcano with its domes sitting in an area marked by a distinct topographic gradient in NW direction and intersected by a system of active faults – hence this is an area where earthquakes are not altogether uncommon. People are used to them but – understandably – get uncomfortable when they come in long swarms. This happened 1999 and again in 2005, when a seismic swarm occurred near Ticsani volcano with a normal fault main shock of Mw 5.8, the epicenter close to the summit of Ticsani volcano, and an inferred depth of 4 km below sea level. Ticsani is located quite far inland from the megathrust system of the subduction zone and therefore the question What exactly causes these swarms? was subject of several investigations in subsequent years.
WHAT CAUSES ALL THE RUMBLING?
From May 2005 on there have been several episodes of earthquake swarms in the area, culminating in an Mw 5.8 (moderate) event on 4 Oct. 2005. Uncommon about this was the number and time period of aftershocks (or replicas); while normally replicas for an EQ of that size would go on for a few days only, this time they went on for about 30 days, causing quite a lot of concern in the local residents. There were two hypotheses for this:
1. The first considers stress factors from two parallel local faults pressing against each other and thus causing deformation between them.
2. The second (and by the investigators preferred) hypothesis is, that this seismicity could have been produced by fissuring of rocks as a result of a possible fluid intrusion into Ticsani. This is supported by the fact that the largest number of replicas were distributed right over the volcano, by the long duration of aftershocks, as well as by a (possible) migration of the EQ swarm from SE to the NW of Ticsani. In conclusion, it is assumed that the seismic crisis of Calacoa (main earthquake and series of aftershocks) in October could be seen, at least partially, as a possible revival of Ticsani volcano. This time, though, the pressure exerted by the magma in deep levels of 4 to 12 km, which did cause crustal deformation, was not strong enough for the development of a pre-eruptive stage in Ticsani volcano.
A study by J. Jay et.al (2013) looks at volcano-tectonic interactions using InSAR technology and reveals previously undocumented surface deformation that is occasionally accompanied by seismic activity. It shows that the earthquake swarm near Ticsani volcano in 2005 produced surface deformation centered northwest of the volcano and was accompanied by a north-south elongated subsidence signal to the southeast. “We investigate a possible relationship between the seismicity and the subsidence and find that the swarm generates a stress field which may encourage the opening of fractures oriented parallel to both the elongation of the subsidence signal and the trend of regional faults. Thus, we hypothesize that the Ticsani swarm triggered the subsidence to the southeast by allowing migration of hydrothermal fluids through cracks, similar to the volcanic subsidence observed in southern Chile following the 2010 Maule earthquake and in Japan following the 2011 Tohoku earthquake, though other explanations for the subsidence cannot be ruled out.”
In 2014, OVS-IGP decided to conduct a study of seismic activity and start permanent monitoring of Ticsani:
Between May and September the scientists identified 2230 seismic events, 2112 of which were rock-fracture related earthquakes of ML<3.3. 118 were seismically related to fluid passage (low-frequency events). 334 of the fracture earthquakes showed clear P and S phases. They found a remarkable concentration of foci in the vicinity of the dome D3, extending to the south in the direction of the domes D2 and D1. The focal mechanisms of earthquakes located on the dome were of ‘normal’ type; their location and movement were consistent with a fault F2. The scientists were lucky in that two seismic swarms occurred during the study: On 24 June 2014 a first swarm of 99 events occurred near the dome D3, and on September 26 a second swarm of 440 events happened near the dome D1. The study concluded that fracture earthquake swarms in the Ticsani area occurred as a result of an abrupt intrusion of hydrothermal and/or volcanic fluids into the area of the F2 fault, thereby causing changes in the balance of local tectonic conditions.
On a field trip in November 2015 Ingemmet/OVS scientists found a slight uptick of fumarolic activity in the area to the northeast of the of the volcano’s summit, indicating increased hydrothermal activity, or stronger volcanic fluid circulation, in that sector of the volcano. Thus, based on the results obtained, new field trips were scheduled to install permanent stations for temperature recording and measurement of gases together with the permanent seismic stations.
– Since September 2015 an increase was observed in the seismicity around Ticsani.
– In Febr. 2016 a significant EQ of hybrid type and another of rupture type were recorded.
– In early April there were EQ swarms within the same area, concentrated in two groups: The first group was located very close to the crater, while the second focus of seismicity was 5 km east of the massif, with depths between 4 km and 11 km.
– November 2015 to April ’16, the temperature measured at 30 cm depth in the volcano has remained close to 45°C; however, from 6 to 24 February variations between 45.9 and 22.5°C have been registered. These variations may be related to increased seismicity in this area.
– Rep. April: With two geodetic measurements (EDM) there was no ground deformation detected during 2016. SO² measurements averaged 20 t/d.
The latest report by the Volcanological Observatory INGEMMET (OVI) and the Volcanological Observatory South (OVS) was published on 16 August 2016. There were no earth-shattering news (in the true sense of the word 😉 ) for the time being:
Proximal and Distal VT seismicity has decreased during this period, presenting seismicity rates of 10 and 15 VT /day, respectively. Hybrid earthquakes were few and with low energy.
In this period a total of 151 earthquakes related to rock fracturing were located, with magnitudes between 1.8 and 3.1 ML. The epicentral distribution of these events continues hovering near the volcano Ticsani (VT proximal), with depths reaching 8 km beneath the crater. Also scattered earthquakes (VT distal) were observed, distributed to the SE of this massif. Two earthquakes had a magnitude of 3.1 ML, located 4 km and 8 km E and SE of Ticsani respectively.
TICSANI’S HYDROTHERMAL WATERWORKS
In absence of roiling red-hot lava from this volcano we’ll have a look at its hydrothermal waterworks. Most significant are the thermal springs with very high temperatures, some of which are used as thermal baths at the river Putina. Further up that valley, the “Geiser of Secolaque” used to eject a 9 m hot water fountain which now has decreased to 4 m hight – but instead is sprouting new fumaroles around it. Recently, scientists began to notice and monitor also increased fumarolic activity to the northeast of the volcano summit.
A remarkable feature of this hydrothermal system is its remote positions, not just concentrated on the top of the edifice. There are numerous hot springs located in more than 10 km distance from the top of the volcano. “This is considered to be due to the regional topographic gradient being able to significantly divert the thermal water ﬂow which can lead to an asymmetric emplacement of the hydrothermal system, even considering a homogeneous permeability of the edifice“. (Byrdina et al., 2013) Furthermore, this could be a strong indication that the entire western ﬂank of Ticsani volcano may be altered by hydrothermal activity and therefore more prone to collapses in that direction.
(Btw., the above paper from 2013 also mentions “… ground temperatures up to 37°C observed at Ticsani.”; assuming that scientists would take soil temperature measurements always in the same spot, for comparability, there has been quite a rise if we look at the OVI report from April 2016 stating 45°C.)
Los Geisers en el Rio Putina: These are said to be the most extraordinary thermal springs of the department, located 20 km north of the town of Carumas, at abt. 3000 m a.s.l. at the foot of Volcano Ticsani. In a narrow gorge, through which the Rio Putina flows, those “geysers”, or rather hot springs and fumaroles, have the particularity to emerge along several kilometers of the river. There are sectors in which the hot water shoots under pressure from the rocks, forming jets of water and steam that reach more than three meters high and 90°C; elsewhere, bubbling springs emerge, which are used by the locals for cooking potatoes, eggs, etc. For the large amount of dissolved salts in the water, there are parts with springs at temperatures above 100°C. No doubt, these baths have healing properties, especially for skin diseases and rheumatism.
This wonderful video by Sergio Corcuera shows more of this beautifully rugged landscape than just the fumaroles:
The team of scientists on the “Trail by Fire” (images above and right) also paid a visit to Tucsani for gas/water sampling and measurements. Here is the report from their online diary of that day: “We left beautiful Arequipa city and headed south to Ticsani Volcano. It was an interesting target, because our OVI colleagues had noticed Ticsani’s fumarolic activity to be increasing. The slope of Ticsani is blanketed in sulphur, and the many fumaroles looked perfect for direct sampling! We started probing the ground with some high-tech devices (a meter-long titanium tube) and quickly stumbled onto an old geothermal exploration well completely filled with well-formed sulphur crystals. We started taking measurements, but while waiting for them we realized something was slightly wrong… the soles of Ian’s boots had started to melt! So did Nial’s jacket! And so did Aaron and Yves’ trousers – they were foolishly not wearing their Supertrousers (proven to be fumarole-proof) at the time.” Apparently they used up a few rolls of duct tape before going on to the next volcano! 😀
Investigations as to the volcanos hydrothermal system found that the hydrothermal area, or hot zone, of Ticsani extends all over the top of the volcano. It is found that it covers completely Dome 3 and partially Domes 1 and 2, probably because of volcanic activity. The heat source would be centered under the Dome 3, although the location of the magma reservoir is so far not known.
Disclaimer: I am not a scientist, all information in this (and any of my other posts) is gleaned from the www and/or from books I have read, so hopefully from people who do get things right! 🙂 If you find something not quite right, or if you can add some more interesting stuff, please leave a comment.
Enjoy! – GRANYIA
SOURCES & FURTHER READING
– GVP, Ticsani
– […] remote emplacement of hydrothermal systems w/ examples of Ticsani and Ubinas […] (2013, PDF)
– Seismic crisis in Calacoa (Moquegua) of October 2005 (2006, Spanish, PDF)
– Characteristics of the seismic activity in the region Ticsani volcano in 2014 (2015, Spanish, PDF)
– Volcano-tectonic interactions at Sabancaya and other Peruvian volcanoes revealed by InSAR and seismicity
– Structural control on volcanism at the Ubinas, Huaynaputina, and Ticsani Volcanic Group (UHTVG) (2009, Spanish, PDF)
– Asymmetrical structure, hydrothermal system and edifice stability: The case of Ubinas […] (2014, PDF)
– Observatorio Vulcanológico del Sur and Latest Reports on Ticsani
– Seismograms online: at OVS and at OVI websites (the latter is stuck at the moment)
– IGP Portal
– “Trail by Fire“