{{Short description|Offset at ground-level after earthquakes}} [[File:Fault Scarp Borah Peak Earthquake 1983.jpg|thumb|300px|right|Surface rupture caused by normal faulting along the Lost River Fault, during the 1983 Borah Peak earthquake]]

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 affects the Earth's surface. Surface rupture is opposed by buried rupture, where there is no displacement at ground level. This is a major risk to any structure that is built across a fault zone that may be active, in addition to any risk from ground shaking.<ref name="What is Surface Rupture">{{cite web | access-date=2018-10-19 | url=https://www.usgs.gov/faqs/what-surface-faulting-or-surface-rupture-earthquake?qt-news_science_products=0#qt-news_science_products | title=What is Surface Rupture | publisher=United States Geological Survey}}</ref> Surface rupture entails vertical or horizontal movement, on either side of a ruptured fault. Surface rupture can affect large areas of land.<ref name="Seismic Resilience">{{Cite web |url=http://www.seismicresilience.org.nz/topics/seismic-science-and-site-influences/earthquake-hazards/surface-rupture/ |title=Surface rupture can be caused by vertical or horizontal displacement |date=2018-10-19}}</ref> ==Lack of surface rupture==

[[File:Running track after 1999 Chichi earthquake in Taiwan.jpg|thumb|300px|Surface rupture with folding due to reverse faulting along the Chelungpu Fault during the 1999 Jiji earthquake, Taiwan]]

Not every earthquake results in surface rupture, particularly for smaller and deeper earthquakes.<ref name="What is Surface Rupture"/> In some cases, however, the lack of surface effects is because the fault that moved does not reach the surface. For example, the 1994 Northridge earthquake had a moment magnitude of 6.7, caused major damage in the Los Angeles area, occurred at {{convert|18.2|km|mi|0|abbr=on}} below the Earth's surface, but did not cause surface rupture, because it was a blind thrust earthquake.<ref>{{cite web|url=https://pasadena.wr.usgs.gov/info/nr10/|title=USGS Northridge Earthquake 10th Anniversary|access-date=13 April 2016}}</ref>

==Where surface rupture occurs==

Surface ruptures commonly occur on pre-existing faults. Only rarely are earthquakes (and surface ruptures) associated with faulting on entirely new fault structures.<ref name="Surface Rupture">{{Cite web|url=https://www.earthquakeauthority.com/Prepare-Your-House-Earthquake-Risk/Geologic-Hazards/Surface-Rupture|title=Ground Rupture & Surface Faulting – Earthquake Ground Displacement &#124; CEA|access-date=Jan 1, 2020}}</ref> There is shallow hypocenter, and large fracture energy on the asperities,<ref name="Surface Rupturing and Buried Dynamic-Rupture Models Calibrated with Statistical Observations of Past Earthquakes ">{{cite web | url=https://pubs.geoscienceworld.org/ssa/bssa/article-abstract/98/3/1147/341883/surface-rupturing-and-buried-dynamic-rupture | title=Surface Rupturing and Buried Dynamic-Rupture Models Calibrated with Statistical Observations of Past Earthquakes | publisher=pubs.geoscienceworld.org | access-date=28 October 2018 | author=Dalguer, Luis A.; Miyake, Hiroe; Day, Steven M.; Irikura, Kojiro}}</ref> the asperity shallower than {{convert|5|km|mi}}. Examples of such earthquakes are San Fernando earthquake, Tabas earthquake, and Chi-Chi earthquake.<ref name="Generation Mechanism of Surface and Buried Faults Considering the Effect of Plasticity in a Shallow Crust Structure ">{{cite web | url=http://www.iitk.ac.in/nicee/wcee/article/WCEE2012_1629.pdf | title=Generation Mechanism of Surface and Buried Faults Considering the Effect of Plasticity in a Shallow Crust Structure | publisher=iitk.ac.in | access-date=31 October 2018 | author=Wada, K.; Goto, H.}}</ref>

In surface rupture earthquakes, the large slips of land are concentrated in the shallow parts of the fault.<ref name="Differences in ground motion and fault rupture process between the surface and buried rupture earthquakes">{{cite web | url=https://www.terrapub.co.jp/journals/EPS/pdf/2004/5601/56010003.pdf | title=Differences in ground motion and fault rupture process between the surface and buried rupture earthquakes | publisher=Earth Planets Space | date=14 March 2004 | access-date=26 October 2018}}</ref> And, notably, permanent ground displacements which are measureable can be produced by shallow earthquakes, of magnitude M5 and greater.<ref name="Earthquake Processes and Effects">{{Cite web |url=https://earthquake.usgs.gov/research/eqproc/grdmotion.php |title=Earthquake Processes and Effects |publisher=United States Geological Survey}}</ref>

==Types of surface rupture== The form that surface rupturing takes depends on two things: the nature of the material at the surface and the type of fault movement.

[[File:Earthquake- road crack.jpg|thumb|300px|Consequences of the Chi-Chi earthquake, Jiji, Nantou County, Taiwan]]

===Effect of surface lithology=== Where there are thick superficial deposits overlying the trace of the faults, the resulting surface effects are typically more discontinuous. Where there is little or no superficial deposits, the surface rupture is generally continuous, except where the earthquake rupture affects more than one fault, which can lead to complex patterns of surface faulting, such as in the 1992 Landers earthquake.<ref>{{Cite journal |last1=Zachariesen J. |last2=Sieh K. |year=1995 |title=The transfer of slip between two en echelon strike-slip faults: A case study from the 1992 Landers earthquake, southern California |url=https://earthobservatory.sg/files/publications/pdf/The%20transfer%20of%20slip%20between%20two%20en%20echelon%20strike-slip%20faults.pdf |journal=Journal of Geophysical Research |volume=100 |issue=B8 |pages=15,281–15,301 |doi=10.1029/95JB00918|bibcode=1995JGR...10015281Z |hdl=10220/8475 }}</ref>

===Normal faulting=== Surface ruptures associated with normal faults are typically simple fault scarps. Where there are significant superficial deposits, sections with more oblique faulting may form sets of en-echelon scarp segments. Antithetic faults may also develop, giving rise to surface grabens.

===Reverse faulting===

Reverse faulting (particularly thrust faulting) is associated with more complex surface rupture patterns since the protruding unsupported part of the hanging-wall of the fault is liable to collapse. In addition there may be surface folding and back-thrust development.

===Strike-slip faulting=== thumb|300px|Extent of surface rupture caused by strike-slip faulting during the 2002 Denali earthquake [[File:Rupture near Thazi.webm|thumb|CCTV capturing a rupture shifting the ground during the 2025 Myanmar earthquake. This video marked the first recorded evidence of an earthquake rupture in-motion,<ref>{{Cite web|url=https://gizmodo.com/shocking-video-shows-earth-tearing-open-during-myanmars-earthquake-in-march-2000602097|title=Shocking Video Shows Earth Tearing Open During Myanmar's Earthquake in March|last=Bassi|first=Margherita|date=May 14, 2025|website=Gizmodo|access-date=August 3, 2025}}</ref> as well as the first documentation of a curved slip earthquake.<ref>{{Cite web|url=https://www.smithsonianmag.com/smart-news/cctv-footage-captures-the-first-ever-video-of-an-earthquake-fault-in-motion-shining-a-rare-light-on-seismic-dynamics-180987034/|title=CCTV Footage Captures the First-Ever Video of an Earthquake Fault in Motion, Shining a Rare Light on Seismic Dynamics|last=Hashemi|first=Sara|date=July 24, 2025|website=Smithsonian magazine|access-date=August 3, 2025}}</ref>]] Strike-slip faults are associated with dominantly horizontal movement, leading to relatively simple linear zones of surface rupture where the fault is a simple planar structure. However, many strike-slip faults are formed of overlapping segments, leading to complex zones of normal or reverse faulting depending on the nature of the overlap. Additionally, where there are thick superficial deposits, the rupture typically appears as a set of en-echelon faults.<ref>{{Cite journal |last1=Tchalenko J.S. |last2=Ambraseys N.N. |year=1970 |title=Structural Analysis of the Dasht-e Bayaz (Iran) Earthquake Fractures |journal=GSA Bulletin |volume=81 |issue=1 |pages=41–60 |doi=10.1130/0016-7606(1970)81[41:SAOTDB]2.0.CO;2}}</ref>

==Mitigation==

To retrofit a house to survive surface rupture requires engineered design by geotechnical, and structural or civil engineers. This can be quite expensive.<ref name="Surface Rupture"/>

==Examples== {| class="wikitable sortable" |+ ! Extent !! {{M|w}} !! Location !! Type !! Event |- | {{cvt|34|km}} || 6.9 || Idaho, United States || Normal || 1983 Borah Peak earthquake |- | {{cvt|80|km}}<ref name="Surface Rupture"/> || 7.3 || California, United States || Strike-slip || 1992 Landers earthquake |- | {{cvt|50|km}}<ref>{{Cite web |last=Holzer |first=Thomas |date=August 1995 |title=The 1995 Hanshin-Awaji (Kobe), Japan, Earthquake |url=https://rock.geosociety.org/net/gsatoday/archive/5/8/pdf/i1052-5173-5-8-sci.pdf |access-date=2025-04-12 |website=Geological Society of America}}</ref>|| 6.9 || Hyogo, Japan || Strike-slip || 1995 Kobe earthquake |- | {{cvt|150|km}}<ref name="Reilinger">{{cite journal|last=Reilinger|first=R.E.|author2=Ergintav S.|author3=Bürgmann R.|author4=McClusky S.|author5=Lenk O.|author6=Barka A.|author7=Gurkan O.|author8=Hearn L.|author9=Feigl K.L.|author10=Cakmak R.|author11= Aktug B.|author12=Ozener H.|author13=Töksoz M.N.|name-list-style=amp|year=2000|title=Coseismic and Postseismic Fault Slip for the 17 August 1999, M = 7.5, Izmit, Turkey Earthquake|journal=Science|volume=289|issue=5484|pages=1519–1524|url=ftp://www.ncedc.org/outgoing/burgmann/REPRINTS/Reilinger_SCIENCE2000.pdf|doi=10.1126/science.289.5484.1519|pmid=10968782|archive-url=https://web.archive.org/web/20220409200205/ftp://www.ncedc.org/outgoing/burgmann/REPRINTS/Reilinger_SCIENCE2000.pdf|archive-date=2022-04-09|url-status=dead|bibcode=2000Sci...289.1519R}}</ref> || 7.6 || Turkey || Strike-slip || 1999 İzmit earthquake |- | {{cvt|100|km}} || 7.6 || Taiwan || Thrust || 1999 Jiji earthquake |- | {{cvt|400|km}} || 7.8 || Qinghai, China || Strike-slip || 2001 Kunlun earthquake |- | {{cvt|340|km}}<ref name="Haeussler09">{{cite report |last1=Haeussler |first1=Peter J. |title=Surface Rupture Map of the 2002 M7.9 Denali Fault Earthquake, Alaska; Digital Data |date=2009|series=U.S. Geological Survey Data Series 422 |url=https://pubs.usgs.gov/ds/422/ds422_text.pdf |publisher=United States Geological Survey}}</ref> || 7.9 || Alaska, United States || Strike-slip || 2002 Denali earthquake |- | {{cvt|300|km}} || 7.9 || Sichuan, China || Thrust || 2008 Sichuan earthquake |- | {{cvt|400|km}}<ref name="gazetezebra1">{{cite news |title=Yer kabuğundaki kayma 7 metre 30 santimetreye kadar çıktı|trans-title=The slip in the Earth's crust was up to 7 meters 30 centimeters |url=https://www.gazetezebra.com.tr/yer-kabugundaki-kayma-7-metre-30-santimetreye-kadar-cikti |access-date=15 February 2023 |agency=Gazete Zebra |date=15 February 2023 |language=tr}}</ref> || 7.8 || Turkey || Strike-slip || 2023 Turkey–Syria earthquakes |- | {{cvt|500|km}}<ref>{{cite anss|M 7.7 - 2025 Mandalay, Burma (Myanmar) Earthquake|2025|us7000pn9s}}</ref> || 7.7 || Myanmar || Strike-slip || 2025 Myanmar earthquake |}

==See also== * Aseismic creep * Ground fissure * Vertical displacement

==References== {{Reflist}}

==External links and references==

* [http://www.earthquakegeology.com/materials/projects/1620R-report.pdf A large article about surface rupture]

Category:Earthquake and seismic risk mitigation Category:Seismology Category:Geological hazards