Patterns of Historical Earthquake Rupture in the Iranian Plateau

Patterns of Historical Earthquake Rupture in the Iranian Plateau 123Arjaspa the king of Hiyun; approximately 4000 yearsago] ..... Mount Matan Faryad [Kumes Mountain, inthe epicentral area of the 856.12.22 earthquake of Io --IX +, M -- 7.4] broke off from the PatishkhvargarMountain, and slid down into the middle of the plain[’Miyandasht’, possibly referring to the Miyandasht village11 km north of the Meyamay active fault, or themiddle of the plain in the epicentral region of the 856Kumes/Damghan earthquake] ..." (Bundahishn, XII/32-33: Original/Primal Creation, "Cosmogony"; an ancientreligious text of the Zoroastrians, re-written in theMiddle Iranian, Pahlavi, language of Sassanian DynastyA.D. 224 to 642)."The earthquake effects were not confined to the city[Neyshabur]; one village was transferred bodily from itsplace and came down on another village, of which notrace was left ..." (al-Meqrizi, 1436, describing the1389 Neyshabur earthquake of I o -- IX +, M - 7.3 + )At least four historical earthquakes with M > 7 struckin less than 200 yr (1209-1405) near the city of Neyshaburin northeastern Iran (Melville, 1980; Berberian, 1981,1995b; Ambraseys and Melville, 1982; Berberian and Qorashi,1989, 1999a; Fig. 2). This region is characterized byactive reverse faults that follow the structural grain of theBinalud zone and the Neyshabur magmatic arc, an easterncontinuation of the orogenic belt of the Alborz Mountains(Berberian, 1981). The Neyshabur magmatic arc was formedby subduction of oceanic crust northward beneath Eurasiain Jurassic and Cretaceous time (Berberian and King, 1981;Berberian, 1983a,b).The damage distribution suggests that two of the earthquakes(1270 and 1405) ruptured the 55-km-long Neyshaburreverse fault to the west; whereas the other two (1209 and1389) ruptured the 95-km-long Binalud reverse fault to theeast (Fig. 2). The meizoseismal zones of these earthquakescorrespond to the mapped surface traces of these two faults.Historical records show that in 1209, the district of Neyshaburfrom Neyshabur City in the west to Daneh village in theeast (SE Neyshabur in the Zebarkhan district; see Fig. 2)was totally destroyed (Jovaini, 1260), and in 1389, landslidesfrom the Binalud Mountains in the east destroyed severalvillages in the same region. On the other hand, the 1270and 1405 earthquakes caused soil to be "scattered in the air"in the Neyshabur plain to the west (Fazlollah Hamedani,1304; Hafez-e-Abru, 1414). An ob server, Maulana LotfallahWe focus on earthquakes with M _--> 6.5 and especiallythose with M _--> 7 because these account for most of themoment release and are most likely to be recorded accuratelybecause of their size. An M < 6 event may go unrecorded, Neyshaburi in the village of Esfaris (modern Qadamgah easteven in a civilized region, if losses did not warrant a special of Neyshabur, located in Fig. 2) felt the 1405 shock but didreport, but an M > 7 event in a settled region would probably not report any damage.produce sufficient losses to be recorded and described.The correlation of meizoseismal zones with the mappedThe case histories presented here, all in parts of Iran surface traces of the Binalud and Neyshabur faults carrieswith a long historical record, have faults that appear to interact,resulting in earthquake sequences. The zones of earth-entire length during each earthquake. However, these faultsthe assumption that one of these faults ruptured along itsquakes commonly continue along strike to fault segments are part of a structural zone including the North Neyshabur,that have not sustained large-magnitude historical earthquakes.Historically, quiet zones may indicate (1) an alongmentsof these faults may have ruptured instead or that rup-Esfaris, and Buzhan faults, raising the possibility that segstrikechange in the method of strain release, or (2) Iran’s ture may have occurred on unknown blind faults underlyingrecorded history, long as it is, is still too short to encompass young folds in the Neyshabur plain, or partly blind faultsa complete earthquake cycle, and the quiet zones may be such as the Kal-e-Shur thrust (Fig. 2).segments that will sustain large-magnitude earthquakes in These uncertainties aside, it seems clear that since thethe future.late seventh century A.D., most moment release occurred inThe first two case histories discuss regions along the less than 200 yr on two adjacent zones of faulting that maymountainous northern margin of the Iranian plateau, where have included the Binalud and Neyshabur surface faults. Aftera quiet period of at least 500 yr, a rupture on the Binaludmost faults are characterized by reverse slip. The last fivecase histories cover regions farther south and west within zone (1209) was followed 61 yr later by a rupture on thethe Iranian plateau, where strike-slip faulting is dominant, Neyshabur zone (1270). The Binalud zone ruptured againbut reverse-fault earthquakes are locally significant.180 years after its first rupture (1309), followed 16 yr laterby a second rupture on the Neyshabur zone (1405). SinceNeyshaburthat time, these zones have been relatively quiet, althoughan earthquake of M 6.6 in 1673 may have ruptured the Binaludzone (or another fault to the northeast) damaging onethirdof Neyshabur and half of Mashhad (Fig. 2). Continuationsof this zone of reverse faults along strike to thesoutheast and northwest have not produced major momentrelease in historic time; the Neyshabur Jame’ Mosque of1494, the Shadyakh Mohammad Mahruq Shrine of the fifteenthcentury, and the Qadamgah Shrine built in 1680 arestill standing today. However, the southeastern end of theRivand fault may have sustained an M 6.9 earthquake in1851, damaging the ancient Ma’dan-e-Firuzeh [’TurquoiseMine’].Tehran"Not long ago, an earthquake in Ruyan [mountainsnorth-northwest of Tehran; Figure 3] caused two moun-