View source for 1968 Dasht-e Bayaz and Ferdows earthquakes

{{Short description|Earthquakes in Iran}}
{{Infobox earthquake
|title = 1968 Dasht-e Bayaz and Ferdows earthquakes
|timestamp = 1968-08-31 10:47:43
|isc-event = 818488
|anss-url = iscgem818488
|local-date = {{Start date|1968|08|31}}
|local-time = 14:17:43
|map2 = {{location map+ | Iran
 |places = 
{{Location map~|Iran|lat=34.02|long=58.96|mark=Bullseye1.png|marksize=40}}
{{Location map~|Iran|lat=35.7|long=51.42|label_size=120|label=Tehran|position=left|mark=Green pog.svg}}
 |relief = yes
 |label = 
 |caption =
 |float = right
 |width = 250}}
|duration = 1–2 minutes<ref name=Niazi/>
|magnitude = 7.1 {{M|w|link=y}}<ref name="Walker_etal_2004"/>
|depth = 
|location = {{coord|34.02|N|58.96|E}}
|countries affected = Iran
|intensity = {{MMI|10}}<ref name=Niazi/>
|aftershocks = 6.4 {{M|w|link=y}} Sept 1 at 07:27<ref name=Ambraseys_p165/>
|casualties = 15,000 August 31<ref name=Utsu/> <br> 900 September 1<ref name=Utsu/>
}}

The '''Dasht-e Bayaz and Ferdows earthquakes''' (Persian: زمین‌لرزه ۱۳۴۷ دشت بیاض و زمین لرزه فردوس) occurred in [[Khezri Dasht Beyaz|Dashte Bayaz]], [[Kakhk]] and [[Ferdows]], [[Iran]] 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 ==
{{see also|Alborz|Caspian Depression}}

The [[Iranian plateau]] is confined by the Turan platform in the north and the [[Zagros fold and thrust belt]] and [[Makran Trench]] in the south. The [[Arabian plate]] is converging to the north with the [[Eurasian plate]] at a rate of {{convert|35|mm|sp=us}} per year, and is diffused across a {{convert|1000|km|abbr=on}} zone resulting in continental shortening and thickening throughout the plateau, with [[Fault (geology)#Strike-slip faults|strike-slip]] and reverse faulting present, as well as subduction at the [[Makran|Makran coast]].<ref>{{citation|title=Patterns of historical earthquake rupture in the Iranian Plateau|url=http://www.bssaonline.org/content/89/1/120.abstract|archive-url=https://web.archive.org/web/20120110060340/http://www.bssaonline.org/content/89/1/120.abstract|url-status=dead|archive-date=January 10, 2012|first1=M.|last1=Berberian|authorlink=Manuel Berberian|first2=R.|last2=Yeats|year=1999|journal=Bulletin of the Seismological Society of America|volume=89|number=1|page=120|doi=10.1785/BSSA0890010120 |bibcode=1999BuSSA..89..120B }}</ref>

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.<ref name="Walker_etal_2004">{{Cite journal |last1=Walker |first1=R. |last2=Jackson |first2=J. |last3=Baker |first3=C. |date=2004 |title=Active faulting and seismicity of the Dasht-e-Bayaz region, eastern Iran |journal=Geophysical Journal International |volume=157 |issue=1 |pages=265–282 |doi=10.1111/j.1365-2966.2004.02179.x|bibcode=2004GeoJI.157..265W |doi-access=free }}</ref>

== Earthquakes ==
[[File:USGS Shakemap - 1968 Dasht-e Bayaz earthquake.jpg|thumb|USGS Shakemap for the August 31 event]]

The first earthquake occurred on August 31, 1968, measuring 7.1 on the [[moment magnitude scale]]. The [[focal mechanism]] indicated strike-slip faulting and the observed 80&nbsp;km [[surface rupture]] 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.<ref name="Walker_etal_2004"/> The western end of the Dasht-e-Bayaz Fault ruptured and produced another large [[1979 Ghaenat earthquakes|earthquake in 1979]].<ref name="Walker">{{cite journal |first1=R. T.|last1= Walker|first2= E. A.|last2= Bergman|first3= W.|last3= Szeliga|first4= E. J.|last4= Fielding |title=Insights into the 1968-1997 Dasht-e-Bayaz and Zirkuh earthquake sequences, eastern Iran, from calibrated relocations, InSAR and high-resolution satellite imagery |journal=Geophysical Journal International |date=2011 |volume=187 |issue=3 |pages=1577–1603 |doi=10.1111/j.1365-246X.2011.05213.x |bibcode=2011GeoJI.187.1577W |doi-access=free }}</ref>

==Damage==
The mainshock destroyed five villages in the Dasht-e Bayaz area, and at least half of the buildings in another six villages from [[Kakhk]] to [[Sarayan]]. A strong [[aftershock]] on September 1, measuring 6.4 on the moment magnitude scale, destroyed [[Ferdows]]. More than 175 villages were destroyed or damaged in this earthquake.

== See also ==
*[[List of earthquakes in 1968]]
*[[List of earthquakes in Iran]]

== References ==
{{reflist|refs=	
<ref name=Ambraseys_p165>{{citation|title=A History of Persian Earthquakes|url=https://books.google.com/books?id=1JkfKub5vakC|first1= N. N.|last1=Ambraseys|authorlink=Nicholas Ambraseys|first2=C. P.|last2=Melville|year=1982|series=Cambridge Earth Science Series|publisher=[[Cambridge University Press]]|isbn=978-0521021876|page=165}}</ref>
<ref name=Niazi>{{citation|title=Source dynamics of the Dasht-e Bayāz earthquake of August 31, 1968|url=http://www.bssaonline.org/content/59/5/1843.abstract|first=M.|last=Niazi|year=1969|journal=Bulletin of the Seismological Society of America|volume=59|number=5|pages=1857, 1859|doi=10.1785/BSSA0590051843|bibcode=1969BuSSA..59.1843N}}{{Dead link|date=June 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>
<ref name=Utsu>{{citation|title=International Handbook of Earthquake & Engineering Seismology|series=Part A, Volume 81A|chapter=A List of Deadly Earthquakes in the World: 1500–2000|first=T. R.|last=Utsu|year=2002|publisher=[[Academic Press]]|edition=First|isbn=978-0124406520|page=707}}</ref> 	
}}

==Further reading==
* {{citation|title=The Dasht-e Bayāz (Iran) earthquake of August 31, 1968: A field report|url=http://bssa.geoscienceworld.org/content/59/5/1751.abstract|first1=N.|last1=Ambraseys|first2=J. S.|last2=Tchalenko|year=1969|journal=Bulletin of the Seismological Society of America|volume=59|number=5|pages=1751–1792|doi=10.1785/BSSA0590051751 |bibcode=1969BuSSA..59.1751A }}
* {{citation|title=Aftershocks of the Dasht-e Bayāz, Iran, earthquake of August, 1968|url=http://www.bssaonline.org/content/59/5/1823.abstract|first=S.|last=Crampin|year=1969|journal=Bulletin of the Seismological Society of America|volume=59|number=5|pages=1823–1841|doi=10.1785/BSSA0590051823 |bibcode=1969BuSSA..59.1823C |access-date=2014-09-06|archive-date=2014-12-02|archive-url=https://web.archive.org/web/20141202003321/http://www.bssaonline.org/content/59/5/1823.abstract|url-status=dead}}

==External links==
* [https://web.archive.org/web/20090515045925/http://earthquake.usgs.gov/regional/world/world_deaths.php Earthquakes with 1,000 or More Deaths since 1900] – [[United States Geological Survey]]
* {{EQ-isc-link|818488}}

{{Earthquakes in 1968}}
{{Earthquakes in Iran}}

{{DEFAULTSORT:1968 Dasht-E Bayaz And Ferdows Earthquake}}
[[Category:Earthquakes in Iran|1968 Dasht-e Bayaz and Ferdows]]
[[Category:1968 earthquakes|Dasht-e Bayaz And Ferdows Earthquake, 1968]]
[[Category:1968 in Iran|Earthquake]]
[[Category:History of Razavi Khorasan province]]
[[Category:History of South Khorasan province]]
[[Category:Earthquake clusters, swarms, and sequences]]
[[Category:Strike-slip earthquakes]]
[[Category:August 1968 events in Asia]]
[[Category:September 1968 events in Asia]]


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