Editing Earthquake (section)

==== Strike-slip faults ====
[[Strike-slip fault]]s are steep structures where the two sides of the fault slip horizontally past each other; transform boundaries are a particular type of strike-slip fault. Strike-slip faults, particularly continental [[Transform fault|transforms]], can produce major earthquakes up to about magnitude 8. Strike-slip faults tend to be oriented near vertically, resulting in an approximate width of {{cvt|10|km|||}} within the brittle crust.<ref>{{cite web |title=Instrumental California Earthquake Catalog |url=http://wgcep.org/data-inst_eq_cat |url-status=dead |archive-url=https://web.archive.org/web/20110725021215/http://wgcep.org/data-inst_eq_cat |archive-date=2011-07-25 |access-date=2011-07-24 |publisher=WGCEP}}</ref> Thus, earthquakes with magnitudes much larger than 8 are not possible.

[[File:Kluft-photo-Carrizo-Plain-Nov-2007-Img 0327.jpg|thumb|left|Aerial photo of the San Andreas Fault in the [[Carrizo Plain]], northwest of Los Angeles]]

In addition, there exists a hierarchy of stress levels in the three fault types. Thrust faults are generated by the highest, strike-slip by intermediate, and normal faults by the lowest stress levels.<ref>{{cite journal | last1 = Schorlemmer | first1 = D. | last2 = Wiemer | first2 = S. | last3 = Wyss | first3 = M. | year = 2005 | title = Variations in earthquake-size distribution across different stress regimes | journal = Nature | volume = 437 | issue = 7058| pages = 539–542 |bibcode = 2005Natur.437..539S |doi = 10.1038/nature04094 | pmid = 16177788 | s2cid = 4327471 }}</ref> This can easily be understood by considering the direction of the greatest principal stress, the direction of the force that "pushes" the rock mass during the faulting. In the case of normal faults, the rock mass is pushed down in a vertical direction, thus the pushing force (''greatest'' principal stress) equals the weight of the rock mass itself. In the case of thrusting, the rock mass "escapes" in the direction of the least principal stress, namely upward, lifting the rock mass, and thus, the overburden equals the ''least'' principal stress. Strike-slip faulting is intermediate between the other two types described above. This difference in stress regime in the three faulting environments can contribute to differences in stress drop during faulting, which contributes to differences in the radiated energy, regardless of fault dimensions.