Editing Earthquake prediction (section)

== Difficulty or impossibility ==
As the preceding examples show, the record of earthquake prediction has been disappointing.<ref>{{Harvnb|Geller|1997}} found "no obvious successes".</ref> The optimism of the 1970s that routine prediction of earthquakes would be "soon", perhaps within ten years,<ref>{{Harvnb|Panel on Earthquake Prediction|1976|p=2}}.</ref> was coming up disappointingly short by the 1990s,<ref>{{Harvnb|Kagan|1997b|p=505}} "The results of efforts to develop earthquake prediction methods over the last 30 years have been disappointing: after many monographs and conferences and thousands of papers we are no closer to a working forecast than we were in the 1960s".</ref> and many scientists began wondering why. By 1997 it was being positively stated that earthquakes can ''not'' be predicted,<ref name=":12"/> which led to a notable debate in 1999 on whether prediction of individual earthquakes is a realistic scientific goal.<ref>{{Harvnb|Main|1999}}.</ref>

Earthquake prediction may have failed only because it is "fiendishly difficult"<ref>{{Harvnb|Geller|Jackson|Kagan|Mulargia|1997|p=1617}}.</ref> and still beyond the current competency of science. Despite the confident announcement four decades ago that seismology was "on the verge" of making reliable predictions,<ref name=":4"/> there may yet be an underestimation of the difficulties. As early as 1978 it was reported that earthquake rupture might be complicated by "heterogeneous distribution of mechanical properties along the fault",<ref>{{Harvnb|Kanamori|Stewart|1978|loc=abstract}}.</ref> and in 1986 that geometrical irregularities in the fault surface "appear to exert major controls on the starting and stopping of ruptures".<ref>{{Harvnb|Sibson|1986}}.</ref> Another study attributed significant differences in fault behavior to the maturity of the fault.{{efn|1=More mature faults presumably slip more readily because they have been ground smoother and flatter.<ref>{{Harvnb|Cowan|Nicol|Tonkin|1996}}.</ref>}} These kinds of complexities are not reflected in current prediction methods.<ref>{{Harvtxt|Schwartz|Coppersmith|1984|pp=5696–7}} argued that the characteristics of fault rupture on a given fault "can be considered essentially constant through several seismic cycles". The expectation of a regular rate of occurrence that accounts for all other factors was rather disappointed by the lateness of the [[#Parkfield|Parkfield earthquake]].</ref>

Seismology may even yet lack an adequate grasp of its most central concept, [[#Elastic rebound|elastic rebound theory]]. A simulation that explored assumptions regarding the distribution of slip found results "not in agreement with the classical view of the elastic rebound theory". (This was attributed to details of fault heterogeneity not accounted for in the theory.<ref>{{Harvnb|Ziv|Cochard|Schmittbuhl|2007}}.</ref>)

Earthquake prediction may be intrinsically impossible. In 1997, it has been argued that the Earth is in a state of [[self-organized criticality]] "where any small earthquake has some probability of cascading into a large event".<ref>{{Harvnb|Geller|Jackson|Kagan|Mulargia|1997|p=1616}}; {{Harvnb|Kagan|1997b|p=517}}. See also {{Harvnb|Kagan|1997b|p=520}}, {{Harvnb|Vidale|1996}} and especially {{Harvnb|Geller|1997|loc=§9.1, "Chaos, SOC, and predictability"}}.</ref> It has also been argued on decision-theoretic grounds that "prediction of major earthquakes is, in any practical sense, impossible."<ref>{{Harvnb|Matthews|1997}}.</ref> In 2021, a multitude of authors from a variety of universities and research institutes studying the China Seismo-Electromagnetic Satellite reported<ref>{{Harvnb|Martucci|Sparvoli|Bartocci|Battiston|2021}}</ref> that the claims based on self-organized criticality stating that at any moment any small earthquake can eventually cascade to a large event, do not stand<ref>{{Harvnb|Varotsos|Sarlis|Skordas|2020}}</ref> in view of the results obtained to date by [[natural time analysis]].

That earthquake prediction might be intrinsically impossible has been strongly disputed,<ref>E.g., {{Harvnb|Sykes|Shaw|Scholz|1999}} and {{Harvnb|Evison|1999}}.</ref> but the best disproof of impossibility – effective earthquake prediction – has yet to be demonstrated.{{efn|1="Despite over a century of scientific effort, the understanding of earthquake predictability remains immature. This lack of understanding is reflected in the inability to predict large earthquakes in the deterministic short-term sense."<ref>{{Harvnb|ICEF|2011|p=360}}.</ref>}}