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276

Izvestiya, Physics of the Solid Earth, Vol. 38, No. 4, 2002, pp. 276–290. Translated from Fizika Zemli, No. 4, 2002, pp. 31–47.Original Russian Text Copyright © 2002 by Ulomov, Polyakova, Medvedeva.English Translation Copyright © 2002 by

MAIK “Nauka

/Interperiodica” (Russia).

INTRODUCTION

Starting the development of the earthquake predic-tion problem in the first half of the last century, Acade-mician G.A. Gamburtsev was convinced that the natureand conditions of earthquake occurrence can be suc-cessfully studied solely on the basis of a multidisci-plinary approach using geological, geophysical, andseismological data. Believing that a close relation existsbetween the earthquake prediction research and seismiczoning, he emphasized that particular attention shouldbe paid to the diversity of seismic and tectonic condi-tions in a given region. In his last publication devotedto this problem, Gamburtsev [1955] wrote: “Seismo-logical data should be checked and complemented bytectonic analysis and deep geophysical survey (analysisof gravity and magnetic anomalies and deep seismicsounding of crust). Tectonic and seismological studiesplay the main role in the seismic zoning of large terri-tories… The current state of seismology, dominated byseismic statistics, is unnatural. Later, as our knowledgeof the nature of earthquakes and conditions of theirorigination will be improved, the role of seismic statis-tics should decrease and, accordingly, well-establishedphysical and geological criteria should play the princi-pal role.” In his note “The Problem of Earthquake Pre-diction” written in March 1954, Gamburtsev suggestedthat “the earthquake prediction criteria … should beestablished on a new basis provided by the physicalapproach to the study of the general deep process

involving the development of crust” both in individualregions and throughout the Earth.

Further research in seismic zoning and earthquakeprediction showed that spatial–temporal and seis-mogeodynamic features indicating the preparation oflarge seismic events should actually be treated withinthe framework of a system encompassing various hier-archical levels of seismic activation on global, regional,local, and source scales [Ulomov, 1983, 1993a, 1993b].Larger seismic sources and accordingly higher magni-tudes of related earthquakes imply larger volumes ofthe geological medium involved in the preparation pro-cess of these earthquakes. Therefore, the study of thesource-seismicity seismic regime and the assessment ofseismic hazard in a given territory should take intoaccount specific dimensions of genetically interrelatedgeostructures of seismically active regions. As regardsthe largest seismic sources, such geostructures canextend for a few thousands of kilometers and theirwidth can reach a few hundreds of kilometers [Ulomov,1993b]. In any case, the size (diameter) of a territorythat can include the source of an earthquake of a givenmagnitude is at least four times larger than the dimen-sions of the source studied.

The temporal development of seismic and seismo-logical processes is also studied on long- and short-term levels: the higher the magnitude of earthquakesstudied, the longer the time interval to be analyzed.

On the Long-Term Prediction of Strong Earthquakesin Central Asia and the Black Sea–Caspian Region

V. I. Ulomov, T. P. Polyakova, and N. S. Medvedeva

Schmidt United Institute of Physics of the Earth, Russian Academy of Sciences,ul. Bol’shaya Gruzinskaya 10, Moscow, 123810 Russia

Received December 17, 2001

Abstract

—This paper discusses the long-term prediction of two strong,

M

≈

7.5 (intensity of 9–10), CentralAsia earthquakes of 1976 and 1992 that occurred in the Gazli (Turan plate) and Suusamyr (North Tien Shan)areas, respectively. Long before each of the events, earthquakes of such strength were predicted in this region,and three main prognostic parameters, namely, the earthquake magnitude (

M

> 7.0), position of potentialsources, and expectation time intervals, were determined. In both cases, the potential sources were located inareas where earthquakes of such magnitudes had not occurred previously and where seismic intensities did notexceed an MSK-64 value of 6. The prediction studies within the Turan plate, distinguished by very weak seis-micity, were based on long-term strainmeter observations of the recent tectonic fracturing process near the epi-central zone of the expected earthquake. The prediction studies in the seismically active North Tien Shan regionwere based on the analysis of its seismic regime patterns and prevailing distances between earthquake epicen-ters. A new method is proposed for the monitoring of regional seismogeodynamic processes, and results ofstudying time variation patterns in the occurrence of earthquakes of various magnitudes are discussed. The cur-rent prediction of

M

> 7.0 earthquakes in Central Asia and the Black Sea–Caspian region is presented.

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ON THE LONG-TERM PREDICTION 277

By analogy with meteorology and with regard tospace–time scales, a region as a whole is usually char-acterized by a “seismic climate,” whereas the “seismicweather” of the region appreciably varies over certaintime intervals (Fig. 1). (Other similarity featuresbetween seismology and adjacent areas of Earth sci-ences are also known. Thus, meteorology deals withmotions of air fluxes; oceanology, with motions ofwater masses; and seismology, with motions of lithos-pheric plates and deformation of solid shells of theEarth.)

The mapping of the seismic climate imitates seismiczoning, which predicts the place and maximumstrength of earthquakes possible within a given region.Because the seismic hazard assessment is based in thiscase not on the prediction of each individual seismicevent but on the seismic effect created by the set of suchevents, the knowledge of their occurrence times seemsto be unnecessary. However, the probabilistic approachunderlying the construction of new maps of generalseismic zoning of North Eurasia (GSZ-97 maps)involves the presence of the time factor in the form ofthe probability of seismic events occurring within giventime intervals [Ulomov and Shumilina, 2000].

The prediction of seismic weather implies that,along with the place, magnitude, and intensity of afuture earthquake, its occurrence time should also bepredicted. Three types of prediction are usually dealtwith:

long-term prediction, if an earthquake is expected tooccur in a large area, and its expectation time is as longas years and decades;

medium-term prediction, if an earthquake isexpected to occur in a relatively small area, and itsexpectation time is a few months or years;

short-term prediction, if the time moment of anearthquake must be predicted with an accuracy of a fewdays or even hours.

On a log scale, these time intervals are similar inlength (see the abscissa axis in Fig. 1). The relationsbetween earthquake characteristics (magnitude, sourcesize, etc.) and dimensions of areas involved in theirpreparation obey similar (power and fractal) laws (e.g.,see [Ulomov, 1974, 1983, 1998]).

Seismic zoning is the best-developed approach. Asregards the earthquake occurrence time, its short-termprediction is least effective, notwithstanding the largebody of experimental data on very diverse precursorsaccumulated over many decades [Mogi, 1985; MaZongjin

et al.

, 1989; Sobolev, 1992]. Evidently, suc-cessful solution of the seismic prediction problem is, ina broad sense, directly related not only to the progressin theoretical and applied studies of the three types ofprediction but also to their proper coordination.Accordingly, prognostic observations should be suc-cessively conducted, starting from seismic zoningthrough the identification of potential earthquakesources and further to the search of their precursors.

Such successive studies were conducted in CentralAsia in relation to the monitoring of the Gazli earth-quakes of 1976 within the Turan plate [Ulomov, 1972,1974, 1983] and identification of potential sources andlong-term prediction of a large seismic event in the TienShan region [Ulomov, 1990a, 1990b, 1991], where theSuusamyr earthquake of 1992 occurred afterward. Inthis connection, the seismic regime was also studied inCentral Asia regions involved in the preparation of suchstrong events as the Karatag (1907), Chatkal (1946),Khait (1949), and Markansu (1974) earthquakes, com-parable in magnitude with the Gazli and Suusamyrearthquakes [Ulomov, 1990a, 1990b].

All these investigations were based on a regionalapproach including the deep structure, geological his-tory, seismotectonics, and seismogeodynamics of eachseismically active region, as well as prevailing dis-tances between epicenters of earthquakes of various

10

5

Seismic

t

, days10

4

10

3

10

2

10

1

10

0

10

–1

Zoning(centuries)

Long-term (years and decades)

Medium-term(months and years) Short-term

(hours and days)

Earthquake

SEISMIC HAZARD AND EARTHQUAKE PREDICTION

“

C L I M A T E

”Prediction of place and strength

“

W E A T H E R

”Prediction of place, time,

and strength

Fig. 1.

Types of the seismic hazard prediction. The bidirectional arrow indicates the occurrence time of the predicted earthquake.Horizontal bars show the expectation time (given in parentheses) of prediction realization.

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ULOMOV

et al

.

magnitudes and their recurrence periods [Ulomov,1987, 1993].

Various “extraregional” and “formal,” small- andlarge-scale methods and techniques of localizing poten-tial earthquake sources have been extensively studied[Reisner and Ioganson, 1993; Polyakova andMedvedeva, 1991, 1999; Polyakova

et al.

, 1992, 1993,1995]. Applying the method of analogies to the recog-nition of potential sources, some authors used

0.3°

×

0.5°

and smaller map cells, whereas rather large (about

4°

×

4°

) “elementary cells” were used by others. Theexpectation time of seismic events was not predicted inmost of these works, and the structure of the mediumoften is not discussed at all.

Below we focus on the Gazli and Suusamyr earth-quakes, which are similar not only in magnitudes butalso because their prognostic indicators appeared aboutten years before their occurrence times (which is inci-dentally consistent with their magnitudes). Moreover,in both cases, not only possible areas but also expecta-tion times of these events were involved in predictionstudies. It is also important that the occurrence areas ofthese earthquakes (the Turan platform and North TienShan Mountains) substantially differed in geologicaland seismogeodynamic conditions.

Results previously derived by the authors and usedin this study included data obtained within the frame-work of the international program “Assessment of Seis-mic Hazard in Countries of the Black Sea basin andCentral Asia” of the Ministry of Industry and Science ofthe Russian Federation.

DYNAMICS OF THE TURAN PLATE CRUSTAND THE LONG-TERM PREDICTION

OF THE GAZLI EARTHQUAKES

The geological history of Central Asia, whose crustwas almost completely derived from the material of theyoung Turan platform (plate), makes this territoryunique with respect to seismogeodynamic research; theregion includes nearly all types of geodynamic interac-tions between lithospheric plates, ranging from rift-likeTuran structures and Tien Shan transforms to colli-sional structures subduction zone relics in the Pamir–Hindu Kush and mid-Caspian areas [Ulomov, 1974].The Turan plate extends from the mountainous TienShan structures in the east, encompasses the northernCaspian area in the west, and reaches mountainousKopet Dag structures in the south. Being a kind ofbuffer zone between the Eurasian, Indian, and Arabianlithospheric plates, the Turan plate is successivelyinvolved in geodynamic movements developing fromthe Tien Shan in the southeast and from the Kopet Dagin the southwest. These movements accommodate thepressure exerted by the Indian and Arabian plates,respectively. Seismogeodynamic processes of therecent and neotectonic activation manifest themselvesmost clearly in such frontal transitional zones.

A high-magnitude swarm of the Gazli earthquakesof 1976–1984, which were the largest seismic eventsknown in the Kyzyl Kum Desert, occurred in the Turanplate in the southern part of the area between the AmuDarya and Syr Darya Rivers, in the zone of the NE-trending Central Kyzyl Kum faults orthogonal to theNW continuation of the South Tien Shan (Fig. 2). Thetable presents main parameters of these earthquakes:occurrence time, epicentral coordinates, focal depth

H

(km), surface wave magnitude

M

s

, and strike azimuth ofmain seismic source faults

Az

0

. Until the Gazli earth-quakes, all of the officially adopted maps of generalseismic zoning (GSZ) of the former USSR attributedthis area to the 5-intensity zone of seismicity. The sameestimates were adopted by the editorial board of theGSZ map that was prepared in the Institute of Physicsof the Earth for publication in 1976 but was

ad hoc

(andformally) updated and was published only in 1978under the name GSZ-78 [

Karta …

, 1984]. New studiesdevoted to the construction of basically different, prob-abilistic GSZ-97 maps were carried out under the guid-ance of V.I. Ulomov [Ulomov, 1999]. According to theGSZ-97 map, the Turan plate and many other regions ofNorth Eurasia are seismically more hazardous than wassuggested by the GSZ-78 map [Ulomov and Shumilina,1999–2000].

The Gazli earthquakes were felt as far as 1000 kmfrom their epicenters, and their ground motions wereobserved nearly all over the territory of Central Asiaand even in the East Caucasus. Their intensity associ-ated with the second, strongest earthquake of May 17,1976, reached 4 on the eastern coast of the Caspian Sea.An MSK-64 intensity of 9–10 was observed in the epi-central area. Another significant aspect of the Gazliearthquakes is that a unique accelerogram of an under-ground

M

= 7.3 shock was obtained in their epicentralarea and recorded ground motion accelerationsexceeded the gravity acceleration for the first time inthe worldwide seismological practice (the vertical andhorizontal components amounted to 1.26

g

and 0.9

g

,respectively).

The Kyzyl Kum Desert in the central part of theTuran plate is characterized on the whole by very weakseismicity, although the Chiili (1929,

M

= 6.4

±

0.3

),Tamdy-Bulak (1932,

M

= 6.2

±

0.3

), and two KyzylKum (1968,

M

= 5.1

±

0.2

) earthquakes were recordedin the northern part of the Amu Darya and Syr Daryainterstream area.

The geological structure of the Turan plate is rela-tively simple. A thick sedimentary cover overlies afolded basement, the depth to which varies from 1–3km in the north of the plate to 2–5 km in its central partand reaches 6 km along the Kopet Dag in the south.Low rock masses continuing the South Tien Shan to thewest (the Nuratau, Tamdytau, and Bukantau ridges) areoccasionally exposed in the central Kyzyl Kum Desert.The topography of the crust base, which is a parametercharacterizing the tectonic development of the region,


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reaches depths of 45–50 km here. Interaction anddeformation of geoblocks in this transitional zone isdirectly related to the dynamics of the lithosphereunderlying the Pamirs, Tien Shan, and Kopet Dagregion. As shown below, the complex interaction oflithospheric plates surrounding the Turan plate canfinally produce rift-like extension structures and strike-slip faults in the central Kyzyl Kum area [Ulomov,1974].

Anomalies of recent slow deformations of the crustand lithosphere are known to be the most promisingprognostic indicators of forthcoming earthquakes.They are primary in relation to all (or nearly all) otherof the known precursors of seismic events. As is evidentfrom observations, recent deformations can be mostinformative in earthquake prediction studies in low-seismicity regions such as the Turan plate. The mostremarkable success of strainmeter observations is thelong-term prediction of the Gazli earthquakes of 1976published ten years before their occurrence; afterward,this prediction was further developed and updated untilthe very earthquakes [Karzhauv and Ulomov, 1966;Ulomov, 1974; and others].

Thus, an active fracturing process of tectonic originstarted developing in the vicinity of the Tamdytau

Ridge and in the surface area of the Tamdy-Bulak set-tlement, and the analysis of this process provided abasis for the prediction of a large earthquake in thisregion [Karzhauv and Ulomov, 1966]. In this connec-tion, a special research area was adjusted in 1968 forstrainmeter observations here, and seismic stations atthe Tamdy-Bulak, Kulkuduk, Nurata, and Dzhizaklocalities were installed for the first time in this region(see Fig. 2). Giant fissures of ancient origin were dis-covered in the northern part of the Tamdy-Bulakresearch area; these fissures are perfectly preserved inthe sandy desert due to their periodical rejuvenation.These fissures, as well as less significant ones on thesurface of the Tamdy-Bulak settlement, were found tobe very sensitive indicators of recent slow tectonicmovements in the region. All of the fissures studiedyield evidence of horizontal extension and right-lateral

Table

Date

ϕ

°

N

λ

°

E

H

, km

M

s

Az, deg

April 8, 1976 40.33 63.67 25 7.0 95

May 17, 1976 40.28 63.38 30 7.3 15

March 20, 1984 40.38 63.36 15 7.2 45

M

= 7.3

M

= 7.0

1

2

6543210

1965 1970 1975 1980

Extension,

motion (

d

, cm)

64° 68°

38°

100 100 km0

42°

72°68°64°60° 46°

46°

42°

Lake Aral Syr Darya R.

Amu Darya R.

Termez

1976

1907

1949

1946

1974

1992

1968–1984

Kul-Kuduk

Nukus

Urgench

Bukhara

Navoi

Karshi

Samarkand

Chardzhou

Nurata

Tamdy-Bulak

Kzyl-Orda

Bishkek

Talas

AndizhanFergana

Dzhambul

Chimkent

Dushanbe

Tashkent

Faizabad

Dzhizak

Kulyab

strikeslip

Fig. 2.

Long-term prediction of the Gazli earthquakes of 1976. The circles are sources of earthquakes of similar magnitudes (

M

=7.5

±

0.2

) that occurred before the Gazli events: Karatag, 1907; Chatkal, 1946; Khait, 1949; and Markansu, 1974. The dashed circleis the source of the Suusamyr earthquakes of 1992. The dashed rectangle is the Tamdy-Bulak prediction research area; three lineswithin this area surface fissures that were observed visually from 1965 through 1967 and instrumentally from 1968 through 1984.Plots showing time variations in the relative motions of walls of these fissures: (

1

) extension; (

2

) strike-slip motion. Vertical arrowsmark the time moments of the Gazli earthquakes. The solid triangles are seismic stations.

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ULOMOV

et al

.

deformations prevailing in this part of the Turan plate(Fig. 3).

Based on the method of reduction of Neogene–Qua-ternary geodynamic movements, maps showing vectorand scalar fields of recent and contemporary geody-namic crustal movements in the Pamirs–Tien Shan andTuran regions were constructed and published longbefore the Gazli earthquakes [Ulomov, 1972, 1974].These studies established that these fields closely cor-relate with the regional structure of seismicity and grav-itational field and interpreted the relationship betweenthe shape of the earthquake recurrence plots andstrength and dynamic properties of crustal and lithos-pheric rocks. Ulomov [1972, 1974] also emphasizedthat the SZ-78 map of seismic zoning adopted at thattime was at variance with the actual seismogeodynamicconditions in this area of western Uzbekistan, and theseismic hazard of the Turan plate was underestimated.

Seismometric and strainmeter observations revealeda regular development pattern of the active fracturingprocess in the central Kyzyl Kum Desert. As seen fromthe plot at the bottom left corner in Fig. 2 illustratingthe development of this process in time, the Kyzyl Kumfissures widened by 5 cm over the 1966–1973 period,

and the relative displacement of their walls (right-lat-eral slip) amounted to 3 cm. During the next year, thewidening of the fissures slowed down, rapidlyincreased in 1975, and slowed down again a fewmonths before the Gazli earthquakes of 1976, whensome of the fissures started to intensely close, whichwas accompanied by left-lateral slips. The anomaly inthe strike-slip component of the fissure wall displace-ment was particularly pronounced in 1975 (a rapidright-lateral slip followed by an equally rapid left-lat-eral one). A series of shocks with magnitudes of 3.5–4.0 was recorded over the same short time interval inthe future epicentral area; these shocks can be classifiedas manifestations of very weak foreshock activity. Therecent tectonic movements changed their sign about ayear before the Gazli earthquakes of 1976 separated by40-day interval; the earthquakes occurred within theaforementioned central Kyzyl Kum orthogonal seis-mogenic zone described in [Ulomov, 1972, 1974].

As seen from Fig. 2, the earthquakes occurred notwithin the research area, as was previously expected,but 150 km to the south. However, the source prepara-tion area of the Gazli earthquakes had a diameter

δ

(km)nearly four times as large as the size of the source itself

Fig. 3.

Extension and right-lateral shear deformations visible at the pavement border crossed by one of numerous fissures presenton the territory of the Tamdy-Bulak settlement (left plate) and giant fissures in the research area (central Kyzyl Kum desert) northof the settlement.


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L

(km), which is consistent with the relations [Ulomov,1987]

δ

M

= 10

(0.6

M

– 1.94)

, (1)

L

M

= 10

(0.6

M

– 2.5)

. (2)

Thus, if a cumulative magnitude of

M

c

= 7.5 isaccepted for the three Gazli earthquakes (i.e., repre-senting them as one event), we obtain

L

= 100 km and

δ

= 363 km. This size (a radius of about 200 km) of thepreparation area is corroborated by distinct manifesta-tion of strain precursors in the Tamdy-Bulak predictionresearch area.

Therefore, it is evident that the published long-termprediction of large earthquakes in the central KyzylKum area has proven correct.

We should note that double and triple earthquakesare characteristic of sources located within the solidcrust typical of platform regions and orogen-to-plat-form transition zones. Here, peculiar dynamics of thecrust and lithosphere as a whole creates and destroysthe strongest bonds between rocks at disjunctive nodesof intersecting or branching faults [Ulomov, 1974,1988]. For example, such were even moderate KyzylKum earthquakes with

M

= 5.1

±

0.2

that occurred onMarch 13 and 14, 1968, immediately north of theTamdy-Bulak research area. The Karatag earthquake of1907, which occurred in the transition zone betweenthe South Tien Shan orogen and the Turan plate, alsoconsisted of two shocks with

M

= 7.4 and 7.3 separatedby a 20-min interval. Among the most significant seis-mic events of this type are the three well-known NewMadrid earthquakes with magnitudes of more than8.0 that occurred successively in the period fromDecember 16, 1811 to February 7, 1812, on the plainterritory of the United States. It is noteworthy that theyoccurred within rifting structures of the MississippiRiver valley. Other examples can also be cited.

The multiyear fracturing process nearly stoppedafter the seismic events of 1976, and strainmeters, evenwith a tenfold sensitivity, recorded no strain variationsat all. Subsequent, much weaker deformations wererecorded about a year before the third,

M

= 7.2,Gazli earthquake, which took place after eight yearsnearly in the same source and apparently released theresidual elastic stresses and deformations in this sourcearea.

Repeated high-precision geodetic measurementsmade in the epicentral zone before and after the Gazliearthquakes revealed three local surface uplifts withamplitudes of 83, 76, and 75 cm; these uplifts, spacedat about 20 km and displaced relative to each other inthe western direction, were located above the respectivesources of the successive earthquakes. The horizontalamplitude of tectonic movements occasionallyexceeded one meter. According to seismological data,focal mechanisms of the Gazli sources extending todepths of 20–25 km are thrust/strike-slip faults motionson which are due to horizontal compressive and nearly

vertical tensile stresses. The faults of the first (April 8,1976) and third (March 20, 1984) earthquakes appear tohave ruptured in the NW direction, whereas a south-westward motion on the fault plane of the main shockof May 17, 1976, has been reliably established, whichcoincides with the strike of the orthogonal centralKyzyl Kum seismogenic fault zone [Ulomov, 1972,1974]. Apparently, the strike-slip component was right-lateral in the sources of the first and third earthquakes,and it was left-lateral in the source of the main earth-quake, which also agrees with the direction of compres-sive stresses exerted by the Arabian plate (via the KopetDag Range).

The origin of the rift-like structure of fissures in thecentral Kyzyl Kum area north of the epicentral zone ofthe Gazli earthquakes may be due to strike-slip motionsof the same type as those responsible for the creation ofpull-apart fractures and the Baikal rift zone [Molnarand Tapponier, 1975]. The presence of horizontal ten-sile stresses is supported by both the observed fractur-ing process and focal mechanisms of the aforemen-tioned Kyzyl Kum earthquakes of 1968 that occurredimmediately north of the Tamdy-Bulak research area.Their sources are characterized by normal faults and byclearly expressed horizontal tensile and nearly verticalcompressive components of tectonic stresses.

THE SEISMICITY VARIATION AND THE LONG-TERM PREDICTION OF THE SUUSAMYR

(NORTH TIEN SHAN) EARTHQUAKE

The Suusamyr,

M

= 7.5, earthquake of August 19,1992, occurred on the southern slope of the SuusamyrRidge on the territory of Kyrgyzstan (Figs. 2 and 4).Various aspects of this earthquake were extensivelystudied [Dzhanuzakov

et al.

, 1997; Mellors

et al.

,1997; Ghose

et al.

, 1997; and others]. Its epicenterdetermined from instrumental data was located at(

42.07°

N,

73.63°

E), and its hypocentral depth was25 km, which agrees well with its macroseismic conse-quences. The seismic fault motion of an E–W strikewas of the reverse/strike-slip type and took place on afault plane steeply dipping south [

Regional …

, 1992;Dzhanuzakov

et al.

, 1997]. Similar to many otherearthquakes (e.g., the Spitak (1988), Racha (1991), andNeftegorsk (1995) events), the source of the Suusamyrearthquake arose not along the main tectonic faults, asmight be expected, but at an angle with them and waslocated in less significant structures. Supposedly, creepmotions producing the most intense deformations and“skewing” adjacent faults prevail in such cases alongmain faults. A similar example is the Chatkal earth-quake of 1946, which arose on the secondary Atoinokfault rather than along the major Talas-Fergana strike-slip fault (Fig. 4).

The Suusamyr earthquake was felt throughout Cen-tral Asia. The 5-intensity zone extended for more than800 km and included Tashkent (the capital of Uzbeki-stan) in the west and Almaty (the former capital of

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ULOMOV et al.

Kazakhstan) in the east. The seismic intensity reached9–10 in the epicentral area, and this indicated oncemore the imperfection of the then-adopted SZ-78 mapof the former USSR, according to which the epicentralzone of the Suusamyr earthquake was located at theboundary between 7- and 8-intensity zones [Karta …,1984] (Fig. 5). The imperfection of the SZ-78 map isalso indicated by the Spitak (1988), Zaisan (1990),Racha (1991), Khailinskoe (1991), and Neftegorsk(1995) earthquakes, whose intensities exceeded the val-ues shown in the map by 2–3. Our studies related to thecreation of a new set of North Eurasia GSZ maps(GSZ-97) showed that a main drawback of the SZ-78map was the fact that its creation was not based on asystematic approach to the assessment of seismic haz-ard and any fundamental seismogeodynamic model ofearthquake sources [Ulomov, 1999; Ulomov and Shu-milina, 1999–2000]. At that time, each republic of the

former USSR and each region of the Russian Federa-tion created its own fragment of the SZ-78 map, apply-ing its own approach and analyzing only its own terri-tories. Afterward, these separate and sometimes mis-matching fragments were somehow joined at theInstitute of Physics of the Earth (Moscow).

According to its magnitude, the Suusamyr earth-quake was the largest seismic event in the western partof the North Tien Shan, and the only stronger event herewas the Chatkal (M = 7.5) earthquake of 1946; as men-tioned before, the latter occurred on the Atoinok fault,which is a branch of the major Talas-Fergana right-lat-eral fault located at the junction of geological structuresof Caledonian and Hercynian ages. Only two historicalearthquakes (Belovodsk, 1885, M = 6.9 and Merke,1865, M = 6.4) took place within a 200-km radius fromthe Suusamyr earthquake epicenter, determining thezone responsible for such an earthquake; their sources

72° 75°

72° 75°

42° 42°

50 0 50 100 150 km

Andizhan

Talas

Dzhambul

TFF

Bishkek

1992

198419851988 1983

1946

1885

1992 1938

1889

1887

1911

TFF

Fig. 4. Seismic setting in the source area of the Suusamyr earthquake of 1992. Ellipses are sources of earthquakes with M = 7.0 ±0.2 (extending for 50 km), M = 7.5 ± 0.2 (100 km), and M = 8.0 ± 0.2 (200 km) known from ancient times through 1993. The occur-rence years of these earthquakes are shown within rectangles. The circles of decreasing diameters are sources of earthquakes withmagnitudes of 6.5 ± 0.2 and less. The arrows show the position of weak earthquake swarms that arose before the Suusamyr earth-quake. Their origination times (in years) are also shown. The broken line bounds the area of seismic quiescence. The thick lineshows the trace of the Talas-Fergana fault (TFF); the thin lines are smaller, seismically active faults; and the triangles are towns.

1865

IZVESTIYA, PHYSICS OF THE SOLID EARTH Vol. 38 No. 4 2002


were located west and southwest of Bishkek (seeFig. 4). (Here we should note that the most reliable dataon the seismicity of Central Asia are available only since1865, i.e., since Russia’s annexation of Turkestan.)

In the recent past, the most significant earthquakesin the North Tien Shan region took place east of Bish-kek in offshoots of the Zailiiski and Kungei Alatau,north of Lake Issyk Kul. Some of their sources are seenin the upper right quadrant of Fig. 4: the Vernyi (1887,M = 7.3), Chilik (1889, M = 8.3), and Kemin-Chu(1911, M = 8.2) earthquakes; a weaker (M = 6.9) earth-quake of 1938 occurred southeast of Bishkek.

The Central Asia region is characterized by a40-year periodicity of seismic activation, best con-strained by M ≥ 7.0 earthquakes (Fig. 6) [Ulomov,1974, 1990a]. About 25 years are seismically active(rectangles I, II, and III in Fig. 6), and 15 years are rel-atively quiescent (cross-hatched intervals). A similar40-year cyclicity was noted farther to the south in theHimalayas [Mogi, 1985], which is additional evidence

of a close seismogeodynamic relationship betweenthese two large regions and is beneficial to the long-term prediction of strong earthquakes in Central Asia.

Ulomov [1990a] illustrated the seismic activationperiodicity in the form of a plot (see Fig. 6) and esti-mated the occurrence probability of an M ≥ 7.0 earth-quake in Central Asia for the period from 1989 through1995. He also calculated the probability that an earth-quake will occur at a time moment t2 (years) after thepreceding real event occurring at a time moment t1:

P(t1, t2) = 1 – exp[–n(t2 – t1)]. (3)

Here, n is the average flux density (recurrence) of seis-mic events per unit time (year) within the two lastcycles (II and III). A thick horizontal bar indicates the1989–1995 period of expectation for such an earth-quake to occur in the region. By the moment of publi-cation of the aforementioned paper, the probability ofsuch an earthquake P(t) is seen to have been close to

72° 75°

72° 75°

42° 42°

50 0 50 100 150 km

1992

SZ-78 map fragment

5 6 7 8 9

92

92

92

81

82

82

82

72

72

72

72

65

Bishkek

Lake Issyk Kul

Dzhambul

Talas

Naryn

Osh

Namangan

Andizhan

Fergana

Fig. 5. Position of the Suusamyr, 1992 earthquake source (ellipse) in the seismic zoning map of the former USSR (SZ-78). Indexes1 and 2 of the seismic intensity values indicate the average recurrence periods of the respective events equal to one event per 100years and one event per 1000 years, respectively. The triangles are towns.

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unity and substantially exceeded both the statisticalaverage P(t) = 0.62 and its rms deviation σ.

The prediction was realized as the Suusamyr earth-quake of 1992 (the broken vertical line in Fig. 6, whichwas absent in the original diagram), which occurredwell within the 1989–1995 expectation time interval.Moreover, the source of this earthquake was located inthe close vicinity of the respective potential source (ata distance not greater than the size of the source) thatwas localized two years before the Suusamyr earth-quake among other similar sources of such a rank in theterritory considered (Fig. 7) [Ulomov, 1991].

Figure 7 shows a fragment of the seismotectonicmap presented in the aforementioned paper. (The com-plete diagram illustrating the fractal hierarchical struc-ture of the spatial distribution of seismic lineaments ofvarious ranks in Central Asia was presented in [Ulo-mov, 1993b; Sobolev, 1992].) The black circles showthe sources of earthquakes with M = 7.5 that wereknown by that time (the chosen magnitude value is sim-ilar to that of the Suusamyr earthquake of 1992); theseare the Vernyi (1887), Karatag (1907), Khait (1949),Chatkal (1946), Markansu (1974), and Gazli (1976)earthquakes. The white bands are seismic lineaments(boundaries between geoblocks, or sutures after Gam-burtsev [1955]) of the respective rank (Mmax =7.5 ± 0.2). The shaded circles are potential sources ofearthquakes of a similar magnitude that were localizedby the method of predominant inter-epicenter distances

based on the grid regularization of the source seismicity[Ulomov, 1987a, 1987b, 1998]. This method essen-tially reduces to the fact that the statistically averagedistances δM (km) between epicenters of the nearestpairs of seismic sources having a size LM (km) obey thesame hierarchical dependence on the magnitude M. Asseen from (1) and (2), the value δ/L is independent ofmagnitude, indicating that the distance betweensources of neighboring earthquakes of the same magni-tude is approximately four times as large as the size ofthese sources. The larger the source, the farther it isfrom its neighbor of the same magnitude.

Figure 7 indicates that an M = 7.5 ± 0.2 earthquakecould likewise occur during the predicted period at anyother potential source shown in this figure, because theprognostic plots presented in Fig. 6 are valid through-out the Central Asia territory considered. However, it isimportant that the Suusamyr earthquake confirmed thatwe correctly predicted the position of such a largepotential source in a region where no significant earth-quakes had been known previously. This is why manylocal geologists and seismologists regarded the positionof this potential source as absurd.

In view of the new unified Specialized earthquakecatalog (SEC) of North Eurasia [Kondorskaya and Ulo-mov, 1995] and recent data on weak seismicity of theterritory considered [Dzhanuzakov et al., 1997; Mel-lors et al., 1997; Ghose et al., 1997; Gorbunova et al.,2001], we thought it interesting to retrospectively trace

1880 1900 1920 1940 1960 1980 2000

7.0

7.5

8.0

M

0.5

1.0

01930 1960 1990

P1(t) = 1 – e–nt

1885–1911 1929–1955 1968–1995

I II III

Years1989–1995

Expectation period

Suusamyr,1992, M = 7.5

–P1(t) = 0.62–σ

+σ –

Fig. 6. Periodicity of seismic activation and the probability of earthquakes with M ≥ 7.0 ± 0.2 to occur in the Central Asia region[Ulomov, 1990a]. The vertical bars mark earthquake times, and their height is proportional to the magnitude; the broken verticalline shows the Suusamyr, 1992 earthquake. The upper plot is the occurrence probability of the next earthquake P1(t) in sequencesII and III; ±σ is the standard deviation from the average P = 0.62. The horizontal black bar shows the expectation time of this earth-quake (1989–1995).



the space–time development of the seismic process inthe preparation area of the Suusamyr earthquakesource.

Figure 8 presents yearly maps of M < 3 earthquakesover the 1982–1993 time period. The Suusamyr earth-quake source determined from the epicentral field of itsnumerous aftershocks (see the fragment for the 1992–1993 period) is shown as an open oval.

Whereas data on M ≥ 3.5 earthquakes from theNorth Eurasia catalog yield no evidence of any seismicactivity in the source area of the Suusamyr earthquakeand complete quiescence was observed from 1981 untilthe main event, some evidence for a forthcoming eventcould be gained from weak earthquakes. Startingapparently in 1983, the amount of weak shocks waslargest in 1986, after which (and particularly since1990) the activation was followed by quiescence. At thesame time, swarms of both weak and moderate earth-quakes arose at great distances from the source. Thefirst swarm appeared in 1983 at the southeastern end ofthe Talas-Fergana fault; the second, in 1984–1985 and1988 at the North Fergana fault; and the third, in 1992at the East Fergana fault (see the circles in Fig. 8 and thearrows with dates in Fig. 4). The position and time

36°

42°

70° 80°M = 7.5 ± 0.2

1992

8

47

5

9

10

32

6

c 1990–100 0 100 300 km

1

Fig. 7. Real (solid circles) and potential (shaded circles)sources of M = 7.5 ± 0.2 earthquakes and seismic linea-ments (bands) in eastern Central Asia: (1–6) earthquakes:(1) Vernyi, 1887; (2) Karatag, 1907; (3) Khait, 1949;(4) Chatkal, 1946; (5) Markansu, 1974; (6) Gazli, 1976;(7) potential source in the epicentral zone of the Suusamyrearthquake; (8) source of the Suusamyr, 1992 earthquake;(9) Talas-Fergana fault; (10) Pamir-Hindu Kush deep faultmarking the boundary between the Eurasian and Indianlithospheric plates.

72° 72° 72° 72°

72° 72° 72° 72°

42°

42°

42°

42°

42°

42°

1985198419831982

1989198819871986

1992199119900 100 km

1992–1993

Fig. 8. Space–time development of the weak (M < 3) seismicity process. The open and shaded ovals are the sources of the Suusamyrand Chatkal (1946) earthquakes, respectively. The dots are epicenters of M = 1.5–2.5 earthquakes. The thick line is the Talas-Fer-gana fault. The circles delineate swarms of weak earthquakes that took place in 1983, 1984–1985, 1988, and 1992. Epicenters ofthe first half of the year (before the Suusamyr earthquake) are only shown in the fragment of 1992. The fragment of 1992–1993shows events postdating this event; the aftershock activity is clearly observable in this fragment.

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sequence of these swarms may indicate a deformationwave propagating from the south, i.e., from the Pamirsand Indian plate.

The representativeness of the general catalog join-ing the SEC and data on weak earthquakes is illustratedin Fig. 9, showing the earthquake recurrence plot in amagnitude interval of 1.0–7.5 normalized to a year andreduced to a fixed area. As seen, the plot is nonlinearand gradually flattens out, changing its slope from the“classical” value b = –0.9 in the upper part to b = –0.5in the lower part. Earthquakes with M = 2.0 and 2.5 lie

on the linear segment of the plot. Shocks with M = 1.5and 3.5 can also be considered more-or-less representa-tive. Data on earthquakes with M = 1.0 and 3.0 are lessreliable. However, the general shape of the plot coin-cides with the nonlinear configuration of a similar plotconstructed for the entire territory of the North TienShan, and this is evidence of its reliability and addition-ally supports the idea according to which the recurrenceplots of earthquakes of various magnitudes have differ-ent configurations in regions differing in their fragmen-tation extent [Ulomov, 1974]. Similar to the plot for theentire North Tien Shan, the upward departure from thestraight line with the slope b = –0.9 is evidence thatstrong earthquakes in this region occur much more fre-quently than is suggested by the linear (exponential)extrapolation of the weak-earthquake plot toward largerevents (the thin line in Fig. 9).

Figure 10 illustrates in more detail the developmentof the source itself as constrained by weak seismicity(M < 3). The figure shows an episode of 1986 (as men-tioned above, the trace of the future rupture in theSuusamyr earthquake source became recognizable) andthe sequence of seismic events observed in 1992 in thesame (western) direction (weak foreshock–main event–two aftershocks with M = 6.9 and 6.8).

SEQUENCES OF SEISMIC EVENTSAND PREDICTION OF LARGE EARTHQUAKES

IN THE CENTRAL ASIAAND BLACK SEA–CASPIAN REGIONS

Figure 11 presents sequences of earthquakes inmagnitude intervals of (1) M = 8.0 ± 0.2, (2) M = 7.5 ±0.2, and (3) M = 7.0 ± 0.2 that occurred in the Tien Shanand Turan plate regions from 1880 to the present time(years on the vertical axis). The ordinal numbers (N) ofearthquakes in each of the time sequences are plottedon the abscissa axis. Straight lines approximate thewhole sets of events in each of the sequences, and theapproximating curves are obtained by the B-splineinterpolation of the data. If seismic events occurred reg-ularly in time, they would lie strictly on straight linesand the earthquake occurrence time could be easily pre-dicted. The real situation, albeit imperfect, is character-ized by distinct regular patterns. Thus, the largestevents with M = 8.0 ± 0.2 (plot 1 in Fig. 11) forming adense group occurred within a 20-year time interval.These are the Chilik (1889, M = 8.3), Kashgar (1902,M = 8.1), and Kemin-Chu (1911, M = 8.2) earthquakes.Since then (over more than 90 years) no earthquakes ofsuch magnitudes have occurred in Central Asia, so thatthere are no grounds to discuss the occurrence time ofsimilar events. As regards the two other sequences(plots 2 and 3 in Fig. 11), their regular patterns arebeyond doubt.

The time moments of M = 7.5 ± 0.2 earthquakesinsignificantly deviate from their approximatingstraight line corresponding to an average recurrenceperiod of T = 15 years, and the majority form three

10–1

0 1

NM

Ms2 3 4 5 6 7

10–2

100

101

102

b = –0.9

b = –0.7

b = –0.5b = –0.9

1 2 3

D

C

B

A

7 5

6 8

9

43

2

1

Fig. 9. The earthquake recurrence plot for the territory stud-ied (see Fig. 8). NM is the annual average number of earth-quakes with the magnitude Ms determined from surfacewaves, and b is the slope of the plot and its fractal dimension[Ulomov, 1990b].

Fig. 10. Development of the seismic process in the sourceof the Suusamyr earthquake (see Figs. 4 and 8) in 1986 and1992: (1) source outline; (2) epicenters of weak earthquakesand directions of their migration (arrows); (3) epicenters ofthe foreshock (A), main event (B), and two strong after-shocks (C and D).



groups separated by 40- and 25-year intervals, eachgroup consisting of two closely spaced events. Two iso-lated events of the same magnitude are symmetricallylocated on the sides of extreme groups. A slightly undu-lating spline line deviates insignificantly from theapproximating straight line and has slopes that varywithin narrow limits corresponding to T = 12.5 and17.5 years. Extrapolating this line toward later timessuggests that the future earthquake with M = 7.5 ± 0.2in the study area should occur within a 2002–2015 timeinterval and may coincide with one of the potentialsources shown in Fig. 7.

The plot of successive events with M = 7.0 ± 0.2(plot 3 in Fig. 11) exhibits an equally ordered pattern.The spline curve resembles a sinusoid showing a com-plete (100-year) cycle and having an amplitude corre-sponding to a nearly 15-year time interval with respectto the approximating straight line with a slope of aboutT = 8.5 years, which can be considered as an axis of thesinusoid. The recurrence periods of M = 7.0 ± 0.2 earth-quakes vary within fairly wide limits (from 2.5 to20 years). The upward extrapolation of the sinusoid andits intersection with the ordinate N = 17 indicate a highprobability of an earthquake (no. 17) to occur in thenext decade.

The hatched horizontal band in Fig. 11 marks thetime interval (2002–2015) of the probable occurrenceof large earthquakes in the region considered. The blackcircles are the occurrence times of the next large earth-quakes.

Figure 12 illustrates an example of mathematicallymore rigorous prognostic calculations that we carriedout for the Black Sea–Caspian region embracing theCrimea, the Caucasus, the Kopet Dag, northeasternTurkey, and northern Iran, where the statistics of largeseismic events is much more representative than inCentral Asia. Thus, reliable data are available here overa 2000-year period for earthquakes with M = 8.0 ± 0.2,over a 500-year period for M = 7.5 ± 0.2, and over thelast 200 years for M = 7.0 ± 0.2. Accordingly, a densertime scale on the ordinate axis was chosen. It is note-worthy that earthquake pairs are clearly observablehere even for magnitudes M = 8.0 ± 0.2, and the sinu-soid, for events with M = 7.5 ± 0.2. Earthquakes withM = 7.0 ± 0.2 occur rather regularly, although on alarger time scale in Fig. 12 also reveals a somewhatsine-like behavior here.

Figure 12 also presents the equations approximatingthe observed data and predicting earthquakes for eachof the 8.0 ± 0.2, 7.5 ± 0.2, and 7.0 ± 0.2 magnitudeintervals. Also shown are the correlation coefficients(R2) of the initial data with the approximating curves,standard deviations (SD), and the expected occurrence

years ( ) of current earthquakes (solid circles) esti-mated by the given formulas.

The first and third equations describe the straightlines obtained by the least-squares method, and their

YMP

extrapolation toward later times is simple. Thesequence of M = 7.5 ± 0.2 earthquakes had to beapproximated by a fourth-degree polynomial. Theextrapolation of the latter toward later times predicts anearthquake in the year 2059 ± 18 (4 in Fig. 12). If theinitial data are interpolated by a B-spline, such an earth-quake should have occurred in 2000 (5 in Fig. 12).

In this respect, of interest is the recent strong earth-quake that occurred on December 6, 2000, in western

0 2 4 6 8 10 12 14 16 N1880

1900

1920

1940

1960

1980

2000

Y

1

2 3

M = 8.0 ± 0.2

M = 7.5 ± 0.2M = 7.0 ± 0.2Mp = 7.5 ± 0.2Mp = 7.0 ± 0.2

T =

12.5

τ = 4.5

17.5

12.5

20

2.5 18

15 8.5

2 6 10 14 18 22 26 30 34 n1000

1200

1400

1600

1800

2000

2200Y

1

2

3

45

Y8.0 = 874.2 + 194.51n; N = 6; R2 = 0.89;SD = 141; prediction: Y8.0

p = 2236

Y7.5 = 1542.24 – 66.17n + 25.77n2 – 2.06n3 + 0.051n4;

N = 18; R2 = 0.99; SD = 18; Y7.5p = 2059

Y7.0 = 1837.55 + 4.65n; N = 34; R2 = 0.98;

SD = 5; prediction: Y7.0p = 2000

prognostic trend (1)

prognostic trend (2)

Fig. 11. The sequence of intracrustal earthquakes with M =8.0 ± 0.2, 7.5 ± 0.2, and 7.0 ± 0.2 in the Central Asia region.The black circles are potential earthquakes expected tooccur in the time interval shown as a hatched band in theupper part of the figure. For other explanations see the text.

Fig. 12. The sequence of intracrustal earthquakes with M =8.0 ± 0.2, 7.5 ± 0.2, and 7.0 ± 0.2 in the Black Sea–Caspianregion: (1–3) occurrence times of earthquakes of respectivemagnitudes and the approximating B-spline formulas (Y isthe year, n is the number of an earthquake, N is the numberof seismic events of respective magnitudes, R2 is the corre-lation coefficient, and SD is the standard deviation);(4, 5) approximations of the initial data by various methodsand the predicted earthquakes of the respective magnitudes.

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Turkmenistan near the eastern Caspian coast at theboundary between the Central Asia and Black Sea–Caspian regions. This earthquake is consistent witheach of the plots in Figs. 11 and 12, which were con-structed without regard for this event. Unfortunately,very scarce data are available on the epicentral zone anddisastrous consequences of this Turkmenian earth-quake. (To the best of our knowledge, it was not studiedeven by Turkmenian seismologists due to circum-stances beyond their control.) Data on the seismicsource parameters are also contradictory. Thus, themagnitude and epicentral coordinates as estimated bythe Geophysical Survey of the Russian Academy ofSciences are M = 7.4 and (39.66° N, 54.84° E), thehypocentral depth being conventionally accepted equalto 33 km. On the other hand, according to data of theMediterranean Seismological Center (CSEM), thisearthquake had M = 7.0–7.4, epicentral coordinates of(39.78° N, 54.49° E), and a hypocentral depth of 10 km.Divergences between the focal mechanism determina-tions are less significant. Both nodal planes strikenorthwest, which is consistent with the Cheleken-Kum-dag fault orientation. The reverse fault component ispredominant, and nearly horizontal axes of compres-sive stresses are oriented along an N–S direction.

Judging from its location, the source of this earth-quake can belong to both the Turan plate (Central Asia)and Kopet Dag Range (the Black Sea–Caspian region).Supposedly, such an intermediate position of the source

accounts for reasonable agreement between times ofthis Turkmenian earthquake and potential M = 7.0 ± 0.2events in each of the prognostic plots of Figs. 11 and12, as well as the predicted time of an M = 7.5 ± 0.2earthquake obtained by interpolating initial data by a B-spline in the Black Sea–Caspian region (the shaded cir-cle in Fig. 12).

As regards the epicentral area of this earthquake, weshould note that previous investigations of fluctuationsin the seismic regime of the Caspian region and anom-alous variations in the Caspian Sea level revealed regu-lar features indicating a deep origin common to bothtypes of phenomena [Ulomov, 1999]. The author sup-posed that a strong earthquake was prepared in theregion studied. In this context, the same processes mayhave caused the earthquake of 2000 on the eastern Cas-pian coast.

In conclusion, it is important to note that additionalconstraints on the position of potential sources of forth-coming earthquakes can be gained by studying themigration of seismic activation due to the passage ofdeformation waves along the related fault structures[Ulomov, 1993a]. As an example, Fig. 13 shows anordered migration of seismic sources with M ≈ 7.0along the trans-Caucasian seismically active NE-trend-ing structure. Such sources originated in 1966–1971near the epicentral area of the Erzindzhan, northeasternTurkey earthquake of 1939 (M = 7.8 ± 0.3; 39.8° N,39.4° E) and started to migrate northeast along thisstructure at a rate of 24 km/yr. This event was followedby the Khorasan (1983), Spitak (Armenia, 1988), andRacha (Georgia, 1991) earthquakes. If the observedmigration does not stop, the next earthquake of a simi-lar magnitude should be expected in the North Cauca-sus, most likely, in its eastern part.

CONCLUSION

The study of recent geodynamics and seismicregime patterns on both regional and seismic sourcescales contributes much to our knowledge of the seis-mogenesis, as well as to the improvement of seis-mogeodynamic models and earthquake predictionmethods. The inferred regular patterns in the dynamicsof crust and seismicity manifestations enabled the long-term prediction of earthquakes that were the largest inCentral Asia over the last quarter of the century.

The studies showed that ordered patters in the devel-opment of seismicity, such as grouping of earthquakesin time and the sinusoidal shape of the curves describ-ing sequences of seismic events, are evidence of theexistence of very-long-period deformation wavesinvolving whole regions.

Further research on the ordered patterns in thedevelopment of seismic sources in both time (earth-quake recurrence) and space (distances between sources)is required for more reliable localization of potentialsources and assessment of seismic hazard. The modern

0 200 400 600 800 900 km1930

1940

1950

1960

1970

1980

1990

2000Years

24 km/yr

19926.3

19916.9

19886.91983

6.8

19716.8

19666.8

19397.8

Fig. 13. Spatial–temporal development of seismic processesalong the trans-Caucasian lineament extending for about900 km. The magnitude and year of large earthquakes aregiven near the sources shown as open circles. The arrowshows the direction and rate of seismic migration. For otherexplanations see the text.



GPS-assisted methods of surface strain measurementand the development of new approaches described inthis paper are beneficial to this research. Satellite obser-vations and deployment of continuous monitoring sys-tems in seismically active regions can provide high-pre-cision results even in regions where traditional geodeticobservations are scarce.

ACKNOWLEDGMENTS

This work was supported by the Russian Foundationfor Basic Research, project no. 01-05-64452. Thispaper used the results we previously obtained withinthe framework of the international program “Assess-ment of Seismic Hazard in Countries of the Black SeaBasin and Central Asia” supported by the Ministry ofIndustry and Science of the Russian Federation.

REFERENCES

Dzhanuzakov, K.D., Il’yasov, B.I., Muraliev, A.M., andYudakhin, F.N., The Suusamyr Earthquake of August 19,1992, Zemletryaseniya Severnoi Evrazii v 1992 godu (NorthEurasia Earthquakes of 1992), Moscow: Geoinformmark,1997, pp. 49–54.

Gamburtsev, G.A., The State and Perspectives of EarthquakePrediction Studies, Byull. Soveta Seismol., 1955, no. 1.

Ghose, S., Mellors, R., et al., The M = 7.3, 1992, Suusamyr,Kyrgyzstan, Earthquake in the Tien Shan: 2. AftershockFocal Mechanisms and Surface Deformation, Bull. Seismol.Soc. Am., 1997, vol. 87, no. 1, pp. 23–38.

Gorbunova, I.V., Kal’metyeva, Z.A., Mostryukov, A.O., andSilaeva, O.I., Monitoring of Weak Seismicity (M < 2.5) in theToktogul Hydropower Station Area (Central Tien Shan, Kyr-gyzstan), Trudy mezhdunar. konf. “Geodinamika inapryazhennoe sostoyanie nedr Zemli,” 2–4 oktyabrya2001 g. (Proc. Int. Conf. “Geodynamics and the Stress Stateof the Earth), Novosibirsk, 2001, pp. 101–106.

Karta seismicheskogo raionirovaniya SSSR. Masshtab1 : 5000000. Ob’’yasnitel’naya zapiska (A 1 : 5000000Seismic Zoning Map of the USSR. Explanatory Note), Mos-cow: Nauka, 1984.

Karzhauv, G.K. and Ulomov, V.I., Recent Tectonics and Seis-micity of the Kyzyl Kun Region, Uzb. Geol. Zh., 1966, no. 3.

Kondorskaya, N.V. and Ulomov, V.I., Spetsializirovannyikatalog zemletryasenii Severnoi Evrazii. Baza dannykh (Spe-cialized Catalog of Earthquakes in North Eurasia: Database),Moscow: OIFZ RAN, 1995: http://socrates.wdcb.rssi.ru/scetac/default.htm http://www.scgis.ru/russian/cp1251/rfbr/data_0.html.

Ma Zongjin, Fu Zhengxiang, Zhang Yingzhen, et al., Earth-quake Prediction. Nine Major Earthquakes in China(1966−1976), Beijing: Seismological Press, 1989.

Mellors, R.J., Vernon, F.L., Pavlis, G.L., et al., The M = 7.3,1992, Suusamyr, Kyrgyzstan, Earthquake: 1. Constraints onFault Geometry and Source Parameters Based on After-shocks and Body-Wave Modeling, Bull. Seismol. Soc. Am.,1997, vol. 87, no. 1, pp. 11–22.

Mogi, K., Earthquake Prediction, Tokyo: Academic, 1985.

Molnar, P. and Tapponier, P., Cenozoic Tectonics of Asia:Effects of a Continental Collision, Science, 1975, vol. 189,no. 4201, pp. 419–425.Polyakova, T.P. and Medvedeva, N.S., Variations in the Seis-mological Setting within the Central Mediterranean Beltover 1900–1988 and the Spitak Earthquake, Model’nye inaturnye issledovaniya ochagov zemletryasenii (Model andin Situ Studies of Earthquake Sources), Moscow: IFZ RAN,1991, pp. 100–106.Polyakova, T.P. and Medvedeva, N.S., Seismological Mapsof North Eurasia with Prediction Features: An Approach,Mapping Technique, and Results, Vulkanol. Seismol., 1999,nos. 4–5, pp. 114–120.Polyakova, T.P., Medvedeva, N.S., and Stepanova, M.B.,Seismological Setting in the Central Mediterranean Belt andthe Rudbar, 1990, Earthquake, Fiz. Zemli, 1992, no. 3,pp. 72–79.Polyakova, T.P., Medvedeva, N.S., and Stepanova, M.B.,Estimation of Mmax and Seismological Setting by the Scan-ning Method, Seismichnost’ i seismicheskoe raionirovanieSevernoi Evrazii (Seismicity and Seismic Zoning of NorthEurasia), Moscow: IFZ RAN, 1993, issue 1, pp. 51−56.Polyakova, T.P., Medvedeva, N.S., and Stepanova, M.B.,Analysis of Seismic Setting in the Area of the Zaisan, 1990,Earthquake by the Scanning Method, Fiz. Zemli, 1995, no. 7,pp. 63–68.Regional Catalogue of Earthquakes, 1992, Newbury: ISC,1994.Reisner, G.I. and Ioganson, L.I., The Seismic Potential ofWestern Russia and Other States of the Former USSR, Seis-michnost’ i seismicheskoe raionirovanie Severnoi Evrazii(Seismicity and Seismic Zoning of North Eurasia), Moscow:IFZ RAN, 1993, issue 1, pp. 186–195.Sobolev, G.A., Fizika ochaga i prognoz zemletryasenii(Physics of the Source and Earthquake Prediction), Moscow:GTs–IFZ RAN, 1992.Ulomov, V.I., Glubinnaya struktura zemnoi kory seismoak-tivnoi territorii Zapadnogo Uzbekistana. Seismichnost’Zapadnogo Uzbekistana (Deep Structure of the Crust in theSeismically Active Region of Western Uzbekistan: Seismic-ity of Western Uzbekistan), Tashkent: FAN, 1972.Ulomov, V.I., Dinamika zemnoi kory Srednei Azii i prognozzemletryasenii (Dynamics of the Central Asia Crust andEarthquake Prediction), Tashkent: FAN, 1974.Ulomov, V.I., Plate Tectonics and Seismogeodynamics, Eks-perimental’naya seismologiya v Uzbekistane (ExperimentalSeismology in Uzbekistan), Tashkent: FAN, 1983, pp. 3–25.Ulomov, V.I., Seismogeodynamics of the Transition Zonebetween the Tien Shan and Turan Plate and the Long-TermPrediction of the Gazli Earthquakes, Gazliiskie zemletryaseniya1976 i 1984 gg. (The Gazli Earthquakes of 1976 and 1984),Tashkent: FAN, 1986, pp. 7–18.Ulomov, V.I., On the Size Relationship between Sources andPreparation Areas of Earthquakes, Dokl. Akad. Nauk UzSSR,1987a, no. 9, pp. 39–40.Ulomov, V.I., A Lattice Model of Source Seismicity and Seis-mic Hazard Prediction, Uzbek. Geol. Zh., 1987b, no. 6,pp. 20–25.Ulomov, V.I., Source Seismicity and Long-Term Predictionof Earthquakes, Problemnye voprosy seismologii SredneiAzii (Problems of Uzbekistan Seismology), Tashkent: FAN,1988, pp. 32–87.

290


ULOMOV et al.

Ulomov, V.I., Variation in the Seismic Process and Self-Organization Phenomena, Seismichnost’ territorii Uzbeki-stana (Seismicity of Uzbekistan), Tashkent: FAN, 1990a,pp. 184–199.Ulomov, V.I., A Fractal Lattice Model of the Seismic Processand the Earthquake Recurrence, Seismichnost’ territoriiUzbekistana (Seismicity of Uzbekistan), Tashkent: FAN,1990b, pp. 237–255.Ulomov, V.I., Zoning of Seismic Hazard, Maskan–Arkhit.Stroit. Uzbek. Kazakh. Azerb. Kyrgyz. Tadzhik. Turkmen.,1991, no. 9, pp. 5–8.Ulomov, V.I., Seismogeodynamic Activation Waves andLong-Term Prediction of Earthquakes, Fiz. Zemli, 1993a,no. 4, pp. 43–53.Ulomov, V.I., Global Ordering of Seismogeodynamic Struc-tures and Some Aspects of Seismic Zoning and Long-TernPrediction of Earthquakes, Seismichnost’ i seismicheskoeraionirovanie Severnoi Evrazii (Seismicity and Seismic Zon-ing of North Eurasia), Moscow: IFZ RAN, 1993b, issue 1,pp. 24–44.

Ulomov, V.I., Modeling of Earthquake Source DevelopmentZones on the Basis of Lattice Regularization, Fiz. Zemli,1998, no. 9, pp. 20–38.

Ulomov, V.I., Seismogeodynamics and Seismic Zoning ofNorth Eurasia, Vulkanol. Seismol., 1999, nos. 4–5, pp. 6–22.

Ulomov, V.I., Polyakova, T.P., and Medvedeva, N.S., Seis-mogeodynamics of the Caspian Sea Basin, Fiz. Zemli, 1999,no. 12, pp. 76–82.

Ulomov, V.I. and Shumilina, L.S., Komplekt kart obshchego seis-micheskogo raionirovaniya territorii Rossiiskoi Federatsii—OSR-97. Masshtab 1 : 8000000. Ob’’yasnitel’naya zapiska ispisok gorodov i naselennykh punktov, raspolozhennykh vseismoopasnykh raionakh (A Set of 1 : 8000000 GeneralSeismic Zoning Maps of the Russian Federation (GSZ-97):Explanatory Note and the List of Towns and SettlementsLocated in Regions of Seismic Hazard), Moscow: OIFZ,1999–2000. Karta na 4-kh listakh (A Map in Four Sheets),V.N. Strakhov and V.I. Ulomov, Eds. in Chief, Moscow:OIFZ–ROSKARTOGRAFIYa, 2000.

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