Holocene-historical volcanism and active faults as natural risk factor for Armenia and adjacent ...

26 Pages·2002·2.39 MB·English

Journalof Volcanology andGeothermal Research113 (2002)319^344
www.elsevier.com/locate/jvolgeores
Holocene-historical volcanism and active faults as natural risk
factors for Armenia and adjacent countries
A. Karakhaniana;(cid:1), R. Djrbashianb, V. Trifonovc, H. Philipd, S. Arakeliana,
A. Avagiana
a ‘Georisk’ Scienti¢cResearchCompany,375019,24a Marshal Baghramian Ave., Yerevan,Armenia
b Instituteof Geological Sciences,National Academyof Sciencesof Armenia,Yerevan,Armenia
c Instituteof Geology,RussianAcademy ofSciences, Moscow,Russia
d Montpellier II University, Montpellier, France
Received18May 2000; accepted26June 2001
Abstract
Examples of Holocene-historical volcanism in the territory of Armenia and adjacent areas of Eastern Anatolia
andWesternIranarediscussed.Holocene-historicalactivityisprovedforthevolcanoesofTskhouk^Karckar,Porak,
Vaiyots-Sar, Smbatassar and Ararat. Based on the analysis of remote sensing data, field work, and historical and
archeological information, it is demonstrated that there was a considerable number of cases of volcanic activity in
Armenia and adjacent regions of Turkey, Syria and Iran during the historical period. The Holocene volcanic centers
aresituatedwithinpull-apartbasinstructuresandcontrolledbyactivefaults.Situatedinanareapronetomanytypes
ofnaturalhazards,Armeniaandadjacentcountriesfacehighnaturalrisk.Theevidencepresentedshowsthatvolcanic
hazard also contributes to the natural risk for these countries. 3 2002 Elsevier Science B.V. All rights reserved.
Keywords: volcano; historical eruption; activefault; Armenia
1. Introduction strated (Adiyaman et al., 1998; Dewey et al.,
1986). Evidence of Holocene volcanism in Arme-
The territories of Armenia, adjacent parts of nia has been reported by Balian (1969), Karape-
TurkeyandNWIranareareasofvastandintense tian and Adamian (1973), Azizbekian (1993) and
Quaternary volcanism. There are accounts of Ho- Karakhanian et al. (1997a,b, 1999). Historical
locene ¢ssure eruptions of Nemrout, Sipan, Ton- volcanic activity in the region is commonly lim-
dourek and Ararat volcanoes in Eastern Turkey ited totheNemrout eruption in 1441 and present-
(Yilmaz et al., 1998; Innocenti et al., 1980), and day fumarole activity of the Nemrout, Tondourek
their relation to neotectonic faults can be demon- and Ararat volcanoes (Yilmaz et al., 1998). One
goal of this study is to demonstrate that Holo-
cene-historical volcanism is much more wide-
spread in Armenia and adjacent areas of Turkey
* Corresponding author.Tel.: [phone];
and Iran than is widely recognized and may be
Fax: [phone].
E-mail address: [email protected] (A. Karakhanian). considered a natural risk factor.
0377-0273/02/$ ^ see frontmatter3 2002ElsevierScienceB.V. All rightsreserved.
PII: S0377-0273(01)00264-5
VOLGEO237414-5-02
320 A. Karakhanian et al./Journalof Volcanologyand Geothermal Research 113(2002)319^344
The working technique is based on the analysis tion 1 overlie a Late Pleistocene moraine at the
of an extensive range of high-resolution satellite eastern coast of Lake Aknalich (Fig. 2). Basaltic
images, including those of SPOT, Russian sys- andesites of the Holocene Generation 2 form the
tems, as well as Corona, Landsat-TM, Landsat- northern side of the lava ¢eld (Figs. 2 and 4).
7ETM+, and ERS, and air photos of various The surface of Generation 2 lava is eroded and
scales (1:100000^1:5000). In most of the studied covered by a fragmentary soil layer. In contrast,
regions, detailed ¢eld mapping along with trench- Generation 3 basaltic andesites, forming the
ing, 14C and archeological dating of samples was central part of the lava ¢eld, are not eroded
done. 14C dating was carried out in the Geology (Fig. 5).
Institute of the Russian Academy of Sciences Basaltic andesite eruption centers of the three
(GIN) and in Paris Sud University (UPS), and Holocene generations, and largely of the Pleisto-
archeological dating was done in the Institute of cene generation, are inside a large rhombic struc-
Archaeology and Ethnography of the Armenian ture formed by the segments of the Pambak^Sev-
Academy of Sciences. an active fault (Figs. 2 and 4). This structure is a
New evidence from Armenian chronicles and pull-apart basin bordered in the north and in the
other historical and archeological sources is used south by segments of the main right-lateral strike-
extensively. Considering that the historical record slip Pambak^Sevan fault, which have uplifted
in Armenia accounts for not less than 3000 years, outer walls. Within the pull-apart, the strike of
and the archeological record spans 10000^12000 the Pambak^Sevan fault de£ects for 30‡ changing
years (Arme¤nie, 1996), the evidence can therefore from W-NW to the meridional. Since the regional
cover the entire period of the Holocene. Further, compression component is oriented to the N-NE,
we consider several groups of volcanoes as exam- extension develops inside the pull-apart in a near-
ples of Holocene-historical volcanism in Armenia, meridian direction. The extension is indicated by
adjacent areas of Eastern Turkey and NW Iran, many parallel normal faults having small strike-
including Karckar^Tskhouk, Porak, Vayots-Sar, slip components and delineating tilted blocks.
Smbatassar and Ararat (Fig. 1). Lava covers some segments of these faults. Meri-
dional faults of the eastern and western sides of
the pull-apart are right-slips with a normal com-
2. Tskhouk^Karckar group volcanoes ponent on their inner walls. Holocene eruption
centers of Generations 2 and 3 are aligned in
This group is composed of eight volcanoes meridian-oriented chains directly in the line of
elongated meridionally at the NW slope of the the normal-slip faults of the eastern £ank of the
large Quaternary volcano Tskhouk (I in Figs. 1 pull-apart (Fig. 2). Karakhanian et al. (1997a)
and 2). Volcanoes of the Tskhouk^Karckargroup describe these structures in detail.
areinthecentralpartoftheSiunikvolcanicridge, Within the pull-apart depression, there is a
at an altitude of 3000 m and higher (lat. 35‡44PN, thermal spring (III in Fig. 2) with a temperature
long. 46‡01PE). The volcanoes rest on thick rhyo- of 34‡C on the surface and 97‡C at a depth of
lites and dacites of the Neogene, and basaltic an- 1 km in a boring, which attests to the abnormally
desites of the Early and Middle Pleistocene. Well- high geothermal gradient in the region (6.3‡C per
preserved Holocene lava £ows of the Tskhouk^ 100 m). Many thermal springs with surface tem-
Karckar group are clearly seen in these rocks peratures of 60^80‡C are found within a radius of
(Fig. 3). 40^50 km (Vorotan, Jermouk, Histissou). Across
By the state of preservation, the lava £ows are the pull-apart, petroglyphs, burial kurgans and
classi¢ed into three generations, clearly identi¢- masonry walls are found in abundance on Pleis-
able in air photos and in the ¢eld. Basaltic ande- tocene lava and Holocene £ows of Generation 1.
sites of the comparatively older Generation 1 are Some of their features allow consideration of
intact only in the western part of the Holocene these objects as evidence of long-term evolution
lava ¢eld (Fig. 2). Basaltic andesites of Genera- of an Eneolithic culture of hunters and cattle-
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A. Karakhanian et al./Journalof Volcanologyand Geothermal Research 113(2002)319^344 321
Fig. 1. Active faults and young volcanism in Armenia and adjacent areas. 1, Active strike-slip faults; 2, reverse faults and
thrusts; 3, normal faults; 4, volcanic areas; 5, large volcanoes; 6, pre-Holocene lava £ows; 7, Holocene lava £ows. Digits in the
¢gure: I, Tskhouk^Karckar groupvolcanoes; II, Porakgroup volcanoes; III, Vaiyots-Sar; IV, Smbatassar; V, Ararat; VI, Touz-
hik. Volcanic areas: GVR, Ghegham volcanic ridge; VVR, Vardeniss volcanic ridge; SVR, Siunik volcanic ridge; AVR, Agri-
Dag volcanic ridge; Arg, Aragats stratovolcano; Ar, Ararat stratovolcano. Active faults: PSF, Pambak^Sevan Fault; AKF, Ak-
ery Fault; AhF, Akhourian Fault; ESF, Zheltorechensk^Sarykamis Fault; GR, Garni Fault; AZF, Areni^Zanghezour Fault;
SNF, Sardarapat^Nakhichevan Fault; BTF, Balikghel^North-Tabriz Fault.
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322 A. Karakhanian et al./Journalof Volcanologyand Geothermal Research 113(2002)319^344
Fig.2. Sunikpull-apartbasinwiththeTskhouk^Karckargroupvolcanoes.1, Volcanoes; 2, Generation 1Holocenelava; 3, Gen-
eration 2 lava; 4, Generation 3 Holocene lavas; 5, strike-slip faults; 6, reverse faults; 7, normal faults; 8, petroglyph ¢elds and
ancientstructures.(a) Conceptual geodynamic model of theSunik pull-apartbasin.
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A. Karakhanian et al./Journalof Volcanologyand Geothermal Research 113(2002)319^344 323
Fig. 3. Airphotoof lava£ows forthe Tskhouk^Karckargroupvolcanoes(thesouthern part,see Fig. 1).
breeders. Apparently, microclimate, favorable re- obsidian tools, bones and primitive ceramics.
lief, and thermal and fresh-water resources in the The loam layer also ¢lled the space in the grave.
pull-apartwere convenient for thedevelopmentof 14Cdatingoftheloam(GIN-9603)establishedthe
that culture. ageat4720P140yearsBP.Therefore,Generation
However, there are no petroglyphs and old 3 lava was erupted early in the 3rd millennium
structures on the Holocene lava of Generations BC. Considering the intact condition of Genera-
2 and 3. In the south of the Holocene lava ¢eld tion 2 lavas, they can be 200^300 years older.
(I in Fig. 2), Generation 3 Holocene lava directly Despite the convenience of the pull-apart basin
overlies a petroglyph (Fig. 6). By 14C dating, the for cattle breeding and defense, no traces there
age of the petroglyphs is late 4th^early 3rd mil- indicate the later presence of human beings until
lennium BC (Karakhanian and Saphian, 1970; the period of cattle-breeding settlements of the
Karakhanian et al., 1999). Therefore, the lower 17th^18th centuries AD.
limit age for the lava of Generations 2 and 3 Intense strike-slip motions in the main zone of
should be younger than late 4th^early 3rd millen- the Pambak^Sevan fault at a rate of 5^6 mm/yr
nium BC. (Trifonov et al., 1994) transform into extension
The upper limit age for the eruption of Gener- and subsidence at the pull-apart site. The slip
ation3lavaisestimated bythedatingofasample rate decreases north-to-south along the NE
taken from a burial place near the north £ank of boundary of the pull-apart, but increases on its
theGeneration3lava£ow(IIinFig.2).Blocksof SW £ank. In sum, slip rate on both sides of the
Generation 3 Holocene lava £ow were used to pull-apart basin remains equal to the total slip
build a kurgan over the grave. The blocks rested rate along the Pambak^Sevan fault.
on a man-made layer of piled loam, containing Seismogenic surface ruptures of Holocene age
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324 A. Karakhanian et al./Journalof Volcanologyand Geothermal Research 113(2002)319^344
Fig. 4. Airphoto of Holocenelava £ows fromthe Tskhouk^Karckar groupvolcanoes(the southernpart, see Fig. 1). The arrows
indicate rightstrike-slip faults,forming thebordersof the Sunikpull-apartbasin.
are found on some of the pull-apart faults (IV, V trench.Thesliprate ontheSW£ankfault(1mm/
and VI in Fig. 2). The ruptures are identi¢ed by yr) is much less than the average total slip rate on
scarp steps of varying steepness that indicate the main Pambak^Sevan fault (5^6 mm/yr) and
pulses of motion in alternation with scarp erosion suggests high seismic potential of the pull-apart
periods (Wallace, 1977). Other seismicity indica- and a considerable contribution of strong seismic-
tors are stepwise alternation of extension ditches ity to the total motion on the pull-apart faults.
and compression ridges (typical for seismogenic Seismogenic ruptures can be traced on the lava
slips), distinct dams of temporary watercourses, of Holocene Generations 1 and 2, but are lacking
as well as a clear colluvial wedge revealed in the on Generation 3 Holocene lava.
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A. Karakhanian et al./Journalof Volcanologyand Geothermal Research 113(2002)319^344 325
Fig. 5. Holocene lava £ows of Generation 3 of the Tskhouk^Karckar group volcano, view from the southeast near Site 4 in
Fig. 3.
Findings of petroglyphs upturned and broken mouk and Histissou (65‡C) are 15^20 km away
by seismic motion on the seismogenic fault scarp from the Porak volcano. The Porak volcano is
suggest that the petroglyphs had been created be- 37 km to the NW of the Tskhouk^Karckar vol-
fore the lastearthquake occurred. The earthquake cano group described in Section 2. There are two
is dated to the 3rd millennium BC (Karakhanian largelava£ows, up to21 kmlong,that start from
et al., 1997a, 1999), i.e., about the age oftheGen- the group of Holocene ejecta near the Porak vol-
eration 3 Holocene lava eruption. Early in the3rd cano and spread to the north and northwest. All
millennium,thevolcanic eruption ofGeneration3 Holocene vents of these lava £ows are elongated
lava and the strong earthquake eliminated the in the NW direction and £anked by Pambak^Sev-
Eneolithic culture in that region. The area was an active fault segments.
re-developed only in the Middle Ages. At the site of the Porak volcano group, the
Pambak^Sevan active fault is distributed in two
en echelon right-stepping segments, which deter-
3. Porak group volcanoes mine extension inside the structure they edge. At
the northern termination, the northeasternmost
The volcanoes are at the SE coast of Lake Sev- fault branch bisects the top of the Middle Pleis-
an, on the northern slope of the Vardeniss vol- tocene Khonarassar volcano (I in Figs. 7 and 8).
canicridge,atanaltitudeof2800m(lat.40‡01PN, The Khonarassar volcano cone is displaced along
long.45‡47PE)(IIinFig.1).Thegroupconsistsof the fault for 800 m to the right (Trifonov et al.,
thecentralMiddlePleistocenePorakvolcanowith 1994). The NE and SW fault branches are 2 km
10 parasitic cones and Holocene ¢ssure eruption apart. Both have uplifted outer walls and are
centers (Figs. 7 and 8). Thermal sources of Jer- linked in the south £ank with shorter right-slip
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326 A. Karakhanian et al./Journalof Volcanologyand Geothermal Research 113(2002)319^344
Fig. 6. Holocene lava £ows of Generation 3 in the Tskhouk^Karckar group volcanoes that overlie a 1.2U0.7-m block carved
witha snake petroglyphdated late4th^early3rd millenniumBC.
and normal faults. Therefore, there is a typical Karakhanian, 1999). The lower part of the
structure of a narrow and elongated pull-apart town, containing housing remnants, rests on the
with a central graben depression accommodating surface of the Late Pleistocene lava and is near
Porak volcano and Holocene lava vents. the foot of a Generation 1 Holocene lava £ow.
Based on geological mapping, it is possible to Abovethecity,onthesurfaceoftheGeneration1
distinguish between the three generations of Ho- lava£ow,thereisastrongforti¢cationstructure^
locene basaltic andesite lava £ows. The ¢rst is the a citadel. The age of the town is di⁄cult to esti-
earliest Holocene generation that formed two mate precisely. A pit made in the center of one of
£ows of lava stretching northward into the re- the houses exposed a cultural layer at a depth of
gions of the Karchahpiur (the western £ow) and 1.2 m. It contained an intra-layer of charcoal,
Akounk (the eastern £ow) villages (Fig. 8). Frag- obsidian tools, and primitive ceramics. 14C dating
mentary soil layer covers the surface of Genera- of the 1^2-cm-thick charcoal layer established an
tion 1 lava, while this lava in turn overlies Late age of 3080P40 BP (GIN-9913), and for organics
Pleistocene deposits of Lake Sevan. The Holocene from the loam layer under the charcoal the age
lavaofGeneration2isfoundonthewestern£ank was 3200P40 BP (GIN-9914). Archeological dat-
of Porak volcano, does not have soil cover, and ing based on the analysis of the surface and pit
£owed into Lake Alaghel (Figs. 8 and 9). (1.5^2 m) ceramic samples, and design features of
At Site 2 (Fig. 8), we uncovered the ruins of a the walls and the masonry, dates the town to the
previously unknown ancient town (Philip and pre-Urartian period of 1000^700 BC (Middle Iron
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A. Karakhanian et al./Journalof Volcanologyand Geothermal Research 113(2002)319^344 327
Fig. 7. ERS satellite image of the Porak group volcanoes (the northern part). Arrows point to the active Pambak^Sevan right-
slip fault.A^A ,Khonarassar volcanoconeo¡setby the fault; B, Porakvolcano.
1
Age). However, the town may appear to be even in Fig. 8). Could that be a result of historical
older, considering that the pit did not cut through volcanic activity? We assume such a possibility.
the whole depth of the culture layer. The famous Khorkhor cuneiform inscription,
We found many settlements and forti¢cation belonging to King Argishti I, was found in the
structures of the same age in the vicinity of to- Lake Van region (Eastern Anatolia) (Shultz,
day’s village of Akhpiuradzor, at the northern 1840). The inscription recounts the victorious
and western foot of Porak volcano, and at the military campaign to the north, into the area of
eastern coast of Lake Alaghel (Fig. 8). All old present-day Armenia. One of the inscription col-
structures and settlements are on the lava of Gen- umns reads as follows:
erations 1 and 2, and there are none on Genera- ‘‘Twhen I again (for the second time) laid the
tion 3 lava. Lengthy and multi-tier defense walls siege of the town of Behoura, Mount Bamni in
were found on the lava of Generation 1 and par- the area of Behoura Town was destroyed T;
ticularlyGeneration2attheeasterncoastofLake smoke and soot now rise from it to the sun.
Alaghel. The walls terminate abruptly immedi- When Mount Bamni was destroyed, I took the
ately at the edge of Generation 3 lava £ow (IV town of Behoura.’’
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328 A. Karakhanian et al./Journalof Volcanologyand Geothermal Research 113(2002)319^344
Fig.8. Pull-apart basinwiththePorakgroupvolcanoes.1, Activefaults; 2, volcanoes; 3,pre-Holocene lava£ows; 4, Generation
1 Holocene lavas; 5, Generation 2 Holocene lavas; 6, Generation 3 Holocene lavas; 7, large ancient settlements; 8, old forti¢ca-
tion walls.
Translation accordingtoOhanessian andAbra- micity, volcanism, archeology and history, we can
mian (1981), p. 66 suggest that the ancient town, other settlements
Sardour II, son of Arghishti I, left another cu- and forti¢cation structures found are the remains
neiform inscription: of Behoura, while Porak volcanoes correspond to
‘‘Tthe people who ran away frightened of the Mount Bamni (Fig. 9).
arms and climbed Mount Ushkiani and Bamni; As in the case of Tskhouk^Karckar, the origin
I encircled them and killed, others who escaped ofthePorakgroupofvolcanoesisassociatedwith
were burned by Teishebah the God’’ local extension conditions in the pull-apart basin
translation according to Melikashvili (1960), p. formed by the segments of the Pambak^Sevan
254 active strike-slip fault. Scarps of seismogenic sur-
Historians believe that the northern campaign face ruptures are identi¢ed on the borders of the
of Arghishti I was between 782 and 773 BC and Porak pull-apart. The faults have displaced cem-
assume that Behoura Town and Mount Bamni eteries and walls in the ancient town citadel. Pa-
were in the Lake Sevan basin, within the region leoseismological trenchesmadetothesouthofthe
of the Vardenis volcanic ridge. Teishebah was the old town provide indications of two earthquakes
god of the underground kingdom. We interpret and expose ceramics buried in the paleosoil and
the content of these cuneiform inscriptions as similar to the ones found in the town (Philip and
the description of a volcanic eruption on Mount Karakhanian,1999; Philipetal.,2001).Thelower
Bamni during the campaign of Arghishti I, the limit age for one of the earthquakes with
Urartians’ king. The eruption was accompanied Mv 7.3, estimated by radiocarbon analysis of
by the destruction of Behoura and the death of the paleosoil in the Paris Sud University, is
the people who tried to escape on Mount Bamni. 6640P90 BP (UPS, V/3A) (Philip et al., submit-
Taking into account the evidence from paleoseis- ted). By the same analysis for the second earth-
VOLGEO237414-5-02