Editing Earthquake (section)

===Rupture dynamics===
A tectonic earthquake begins as an area of initial slip on the fault surface that forms the focus. Once the rupture has been initiated, it begins to propagate away from the focus, spreading out along the fault surface. Lateral propagation will continue until either the rupture reaches a barrier, such as the end of a fault segment, or a region on the fault where there is insufficient stress to allow continued rupture. For larger earthquakes, the depth extent of rupture will be constrained downwards by the [[brittle-ductile transition zone]] and upwards by the ground surface. The mechanics of this process are poorly understood because it is difficult either to recreate such rapid movements in a laboratory or to record seismic waves close to a nucleation zone due to strong ground motion.<ref name="NRS"/>

In most cases, the rupture speed approaches, but does not exceed, the [[S wave|shear wave]] (S wave) velocity of the surrounding rock. There are a few exceptions to this:

==== Supershear earthquakes ====
[[File:Kahramanmaraş after 7.8 magnitude earthquake in Türkiye 5.jpg|250px|thumb|right|The [[2023 Turkey–Syria earthquakes]] ruptured along segments of the [[East Anatolian Fault]] at supershear speeds; more than 50,000 people died in both countries.<ref name="MelgarEtAl23">{{cite journal |last1=Melgar |first1=Diego |last2=Taymaz |first2=Tuncay |last3=Ganas |first3=Athanassios |last4=Crowell |first4=Brendan |last5=Öcalan |first5=Taylan |last6=Kahraman |first6=Metin |last7=Tsironi |first7=Varvara |last8=Yolsal-Çevikbilen |first8=Seda |last9=Valkaniotis |first9=Sotiris |last10=Irmak |first10=Tahir Serkan |last11=Eken |first11=Tuna |last12=Erman |first12=Ceyhun |last13=Özkan |first13=Berkan |last14=Dogan |first14=Ali Hasan |last15=Altuntaş |first15=Cemali |title=Sub- and super-shear ruptures during the 2023 Mw 7.8 and Mw 7.6 earthquake doublet in SE Türkiye |journal=Seismica |year=2023 |volume=2 |issue=3 |page=387 |doi=10.26443/seismica.v2i3.387|s2cid=257520761 |doi-access=free |bibcode=2023Seism...2..387M }}</ref>]]
[[Supershear earthquake]] ruptures are known to have propagated at speeds greater than the S wave velocity. These have so far all been observed during large strike-slip events. The unusually wide zone of damage caused by the [[2001 Kunlun earthquake]] has been attributed to the effects of the [[sonic boom]] developed in such earthquakes.

==== Slow earthquakes ====
[[Slow earthquake]] ruptures travel at unusually low velocities. A particularly dangerous form of slow earthquake is the [[tsunami earthquake]], observed where the relatively low felt intensities, caused by the slow propagation speed of some great earthquakes, fail to alert the population of the neighboring coast, as in the [[1896 Sanriku earthquake]].<ref name="NRS">{{cite book|last=National Research Council (U.S.). Committee on the Science of Earthquakes|title=Living on an Active Earth: Perspectives on Earthquake Science|chapter-url=http://www.nap.edu/openbook.php?record_id=10493&page=282|access-date=8 July 2010|year=2003|publisher=National Academies Press|location=Washington, D.C.|isbn=978-0-309-06562-7|page=[https://archive.org/details/livingonactiveea0000unse/page/418 418]|chapter=5. Earthquake Physics and Fault-System Science|url=https://archive.org/details/livingonactiveea0000unse/page/418}}</ref>

====Co-seismic overpressuring and effect of pore pressure====
During an earthquake, high temperatures can develop at the fault plane, increasing pore pressure and consequently vaporization of the groundwater already contained within the rock.<ref name=Sibson>{{cite journal|last1=Sibson |first1= R.H.|year=1973|title=Interactions between Temperature and Pore-Fluid Pressure during Earthquake Faulting and a Mechanism for Partial or Total Stress Relief|journal= Nat. Phys. Sci. |volume=243|issue= 126|pages=66–68|doi= 10.1038/physci243066a0|bibcode= 1973NPhS..243...66S}}</ref><ref name=Rudnicki>{{cite journal|last1=Rudnicki |first1= J.W.|last2=Rice |first2= J.R.|year=2006|title=Effective normal stress alteration due to pore pressure changes induced by dynamic slip propagation on a plane between dissimilar materials|journal= J. Geophys. Res. |volume= 111, B10308|issue= B10|doi=10.1029/2006JB004396|bibcode= 2006JGRB..11110308R|s2cid= 1333820|url=https://dash.harvard.edu/bitstream/1/2668811/1/Rice_PorePressDynSlip.pdf|url-status=live|archive-url=https://web.archive.org/web/20190502041503/https://dash.harvard.edu/bitstream/handle/1/2668811/Rice_PorePressDynSlip.pdf;jsessionid=071046244FA1B0E26418CE95B726BA0E?sequence=1|archive-date=2019-05-02|archive-format=PDF}}</ref><ref name=Guerriero>{{cite journal|last1=Guerriero |first1= V |last2=Mazzoli |first2= S.|year=2021|title=Theory of Effective Stress in Soil and Rock and Implications for Fracturing Processes: A Review|journal=Geosciences  |volume=11|issue= 3 |pages=119|doi=10.3390/geosciences11030119|bibcode= 2021Geosc..11..119G |doi-access=free}}</ref> In the coseismic phase, such an increase can significantly affect slip evolution and speed, in the post-seismic phase it can control the [[Aftershock]] sequence because, after the main event, pore pressure increase slowly propagates into the surrounding fracture network.<ref name=Nur>{{cite journal|last1=Nur |first1= A |last2=Booker |first2= J.R.|year=1972|title=Aftershocks Caused by Pore Fluid Flow?|journal=Science |volume=175|issue= 4024 |pages=885–887|doi= 10.1126/science.175.4024.885 |pmid= 17781062 |bibcode= 1972Sci...175..885N |s2cid= 19354081 }}</ref><ref name=Guerriero /> From the point of view of the [[Mohr-Coulomb theory|Mohr-Coulomb strength theory]], an increase in fluid pressure reduces the normal stress acting on the fault plane that holds it in place, and fluids can exert a lubricating effect. As thermal overpressurization may provide positive feedback between slip and strength fall at the fault plane, a common opinion is that it may enhance the faulting process instability. After the mainshock, the pressure gradient between the fault plane and the neighboring rock causes a fluid flow that increases pore pressure in the surrounding fracture networks; such an increase may trigger new faulting processes by reactivating adjacent faults, giving rise to aftershocks.<ref name=Nur /><ref name=Guerriero /> Analogously, artificial pore pressure increase, by fluid injection in Earth's crust, may [[Induced seismicity|induce seismicity]].