The Dasht-e Bayaz and Ferdows earthquakes (Persian: زمین‌لرزه ۱۳۴۷ دشت بیاض و زمین لرزه فردوس) occurred in Dashte Bayaz,

Kakhk Kakhk () is a city in, and the capital of, Kakhk District of Gonabad County, Razavi Khorasan province, Iran Iran, officially the Islamic Republic of Iran (IRI) and also known as Persia, is a country in West Asia. It borders Ira ...

and

Ferdows Ferdows () is a city in the Central District (Ferdows County), Central District of Ferdows County, South Khorasan province, South Khorasan province, Iran, serving as capital of both the county and the district. It is about south of Mashhad ...

Iran Iran, officially the Islamic Republic of Iran (IRI) and also known as Persia, is a country in West Asia. It borders Iraq to the west, Turkey, Azerbaijan, and Armenia to the northwest, the Caspian Sea to the north, Turkmenistan to the nort ...

in late August and early September 1968. The mainshock measured 7.1 on the moment magnitude scale and had a maximum perceived intensity of X (''Extreme'') on the Mercalli intensity scale. Damage was heavy in the affected areas with thousands of lives lost in the first event and many hundreds more in the second strong event.

Tectonic setting

The

Iranian plateau The Iranian plateau or Persian plateau is a geological feature spanning parts of the Caucasus, Central Asia, South Asia, and West Asia. It makes up part of the Eurasian plate, and is wedged between the Arabian plate and the Indian plate. ...

is confined by the Turan platform in the north and the

Zagros fold and thrust belt The Zagros fold and thrust belt (Zagros FTB) is an approximately long zone of deformed crustal rocks, formed in the foreland of the collision between the Arabian plate and the Eurasian plate. It is host to one of the world's largest petroleum ...

and

Makran Trench The Makran Trench is the physiographic expression of a subduction zone along the northeastern margin of the Gulf of Oman adjacent to the southwestern coast of Balochistan of Pakistan and the southeastern coast of Iran. In this region the oc ...

in the south. The Arabian plate is converging to the north with the Eurasian plate at a rate of per year, and is diffused across a zone resulting in continental shortening and thickening throughout the plateau, with

strike-slip In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

and reverse faulting present, as well as subduction at the

Makran coast Makran (), also mentioned in some sources as ''Mecran'' and ''Mokrān'', is the southern coastal region of Balochistan. It is a semi-desert coastal strip in the Balochistan province in Pakistan and in Iran, along the coast of the Gulf of Oman. I ...

. In eastern Iran, the shortening is accommodate by a combination of relatively short northwest–southeast trending reverse faults, long north–south trending right lateral strike-slip faults and shorter west–east trending left-lateral strike-slip faults.

Earthquakes

USGS Shakemap - 1968 Dasht-e Bayaz earthquake

The first earthquake occurred on 31 August 1968, measuring 7.1 on the

moment magnitude scale The moment magnitude scale (MMS; denoted explicitly with or Mwg, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. was defined in a 1979 paper ...

. The

focal mechanism The focal mechanism of an earthquake describes the Fault (geology)#Slip.2C heave.2C throw, deformation in the Hypocenter, source region that generates the seismic waves. In the case of a Fault (geology), fault-related event, it refers to the ori ...

indicated strike-slip faulting and the observed 80 km

surface rupture In seismology, surface rupture (or ground rupture, or ground displacement) is the visible offset of the ground surface when an earthquake rupture along a Fault (geology), fault affects the Earth's surface. Surface rupture is opposed by buried rup ...

showed that this earthquake resulted from movement on the western part of the west–east trending left-lateral Dasht-e-Bayaz Fault. The greatest observed left-lateral coseismic offset was about 4.5 m, with 2 m being the average observed offset. The western end of the Dasht-e-Bayaz Fault ruptured and produced another large earthquake in 1979.

Damage

The mainshock destroyed five villages in the Dasht-e Bayaz area, and at least half of the buildings in another six villages from

Sarayan Sarayan () is a city in Aysak District of Sarayan County, South Khorasan province, Iran Iran, officially the Islamic Republic of Iran (IRI) and also known as Persia, is a country in West Asia. It borders Iraq to the west, Turkey, ...

. A strong

aftershock In seismology, an aftershock is a smaller earthquake that follows a larger earthquake, in Epicenter, the same area of the Mainshock, main shock, caused as the displaced Crust (geology), crust adjusts to the effects of the main shock. Large earthq ...

on 1 September, measuring 6.4 on the moment magnitude scale, destroyed

. More than 175 villages were destroyed or damaged in this earthquake.

References

External links

Earthquakes with 1,000 or More Deaths since 1900
–

United States Geological Survey The United States Geological Survey (USGS), founded as the Geological Survey, is an agency of the U.S. Department of the Interior whose work spans the disciplines of biology, geography, geology, and hydrology. The agency was founded on Mar ...

* 1968 Dasht-e Bayaz and Ferdows Dasht-e Bayaz And Ferdows Earthquake, 1968

Earthquake An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they ...

History of Razavi Khorasan province History of South Khorasan province Earthquake clusters, swarms, and sequences Strike-slip earthquakes August 1968 in Asia September 1968 in Asia {{Iran-stub

Tectonic setting

Earthquakes

Damage

See also

References

Further reading

External links