Editing Earthquake prediction (section)

===== Freund physics =====
In his investigations of crystalline physics, Friedemann Freund found that water molecules embedded in rock can dissociate into ions if the rock is under intense stress. The resulting charge carriers can generate battery currents under certain conditions. Freund suggested that perhaps these currents could be responsible for earthquake precursors such as electromagnetic radiation, earthquake lights and disturbances of the plasma in the ionosphere.<ref>{{Harvnb|Freund|2000}}.</ref> The study of such currents and interactions is known as "Freund physics".<ref>{{Harvnb|Hough|2010b|pp=133–135}}.</ref><ref>{{Harvnb|Heraud|Centa|Bleier|2015}}.</ref><ref>{{Harvnb|Enriquez|2015}}.</ref>

Most seismologists reject Freund's suggestion that stress-generated signals can be detected and put to use as precursors, for a number of reasons. First, it is believed that stress does not accumulate rapidly before a major earthquake, and thus there is no reason to expect large currents to be rapidly generated. Secondly, seismologists have extensively searched for statistically reliable electrical precursors, using sophisticated instrumentation, and have not identified any such precursors. And thirdly, water in the Earth's crust would cause any generated currents to be absorbed before reaching the surface.<ref>{{Harvnb|Hough|2010b|pp=137–139}}.</ref>

====== Disturbance of the daily cycle of the ionosphere ======
[[File:LAQUILA 2009 ULF.JPG|thumb|upright=1.5|The ULF* recording of the D layer retention of the ionosphere which absorbs EM radiation during the nights before the [[2009 L'Aquila earthquake|earthquake in L'Aquila, Italy on 6/4/2009]]. The anomaly is indicated in red.]]
The [[ionosphere]] usually develops its lower [[Ionosphere#D layer|D layer]] during the day, while at night this layer disappears as the [[Plasma (physics)|plasma]] there turns to [[gas]]. During the night, the [[Ionosphere#F layer|F layer]] of the ionosphere remains formed, in higher altitude than D layer. A [[Waveguide (radio frequency)|waveguide]] for low [[High frequency|HF]] radio frequencies up to 10&nbsp;MHz is formed during the night ([[skywave]] propagation) as the F layer reflects these waves back to the Earth. The skywave is lost during the day, as the D layer absorbs these waves.

Tectonic stresses in the Earth's crust are claimed to cause waves of electric charges<ref>{{Harvnb|Freund|Takeuchi|Lau|2006}}.</ref><ref>{{Harvnb|Freund|Sornette|2007}}.</ref> that travel to the surface of the Earth and affect the ionosphere.<ref>{{Harvnb|Freund|Kulahci|Cyr|Ling|2009}}.</ref> [[Ultra low frequency|ULF]]* recordings{{efn|1=The literature on geophysical phenomena and ionospheric disturbances uses the term ULF (Ultra Low Frequency) to describe the frequency band below 10 Hz. The band referred to as ULF on the Radio wave page corresponds to a different part of the spectrum frequency formerly referred to as VF (Voice Frequency). In this article the term ULF is listed as ULF*.}} of the daily cycle of the ionosphere indicate that the usual cycle could be disturbed a few days before a shallow strong earthquake. When the disturbance occurs, it is observed that either the D layer is lost during the day resulting to ionosphere elevation and skywave formation or the D layer appears at night resulting to lower of the ionosphere and hence absence of skywave.<ref>{{Harvnb|Eftaxias|Athanasopoulou|Balasis|Kalimeri|2009}}.</ref><ref>{{Harvnb|Eftaxias|Balasis|Contoyiannis|Papadimitriou|2010}}.</ref><ref>{{Harvnb|Tsolis|Xenos|2010}}.</ref>

Science centers have developed a network of VLF transmitters and receivers on a global scale that detect changes in skywave. Each receiver is also daisy transmitter for distances of 1000–10,000 kilometers and is operating at different frequencies within the network. The general area under excitation can be determined depending on the density of the network.<ref>{{Harvnb|Rozhnoi|Solovieva|Molchanov|Schwingenschuh|2009}}.</ref><ref>{{Harvnb|Biagi|Maggipinto|Righetti|Loiacono|2011}}.</ref> It was shown on the other hand that global extreme events like magnetic storms or solar flares and local extreme events in the same VLF path like another earthquake or a volcano eruption that occur in near time with the earthquake under evaluation make it difficult or impossible to relate changes in skywave to the earthquake of interest.<ref>{{Harvnb|Politis|Potirakis|Hayakawa|2020}}</ref>

In 2017, an article in the ''Journal of Geophysical Research'' showed that the relationship between ionospheric anomalies and large seismic events (M≥6.0) occurring globally from 2000 to 2014 was based on the presence of solar weather. When the solar data are removed from the time series, the correlation is no longer statistically significant.<ref>{{cite journal |last1=Thomas |first1=JN |last2=Huard |first2=J |last3=Masci |first3=F |title=Thomas, J. N., Huard, J., & Masci, F. (2017). A statistical study of global ionospheric map total electron content changes prior to occurrences of M≥ 6.0 earthquakes during 2000–2014 |journal=Journal of Geophysical Research: Space Physics |date=2017 |volume=122 |issue=2 |pages=2151–2161 |doi=10.1002/2016JA023652 |s2cid=132455032 |ref=Thomas et al 2017|doi-access=free }}</ref> A subsequent article in ''Physics of the Earth and Planetary Interiors'' in 2020 shows that solar weather and ionospheric disturbances are a potential cause to trigger large earthquakes based on this statistical relationship. The proposed mechanism is electromagnetic induction from the ionosphere to the fault zone. Fault fluids are conductive, and can produce [[telluric current]]s at depth. The resulting change in the local magnetic field in the fault triggers dissolution of minerals and weakens the rock, while also potentially changing the groundwater chemistry and level. After the seismic event, different minerals may be precipitated thus changing groundwater chemistry and level again.<ref name="auto"/> This process of mineral dissolution and precipitation before and after an earthquake has been observed in Iceland.<ref>{{cite journal |last1=Andrén |first1=Margareta |last2=Stockmann |first2=Gabrielle |last3=Skelton |first3=Alasdair |title=Coupling between mineral reactions, chemical changes in groundwater, and earthquakes in Iceland |journal=Journal of Geophysical Research: Solid Earth |date=2016 |volume=121 |issue=4 |pages=2315–2337 |doi=10.1002/2015JB012614 |bibcode=2016JGRB..121.2315A |s2cid=131535687 |ref=Andrén et al 2016|doi-access=free }}</ref> This model makes sense of the ionospheric, seismic and groundwater data.

====== Satellite observation of the expected ground temperature declination ======
[[File:Main india night Jan 06-21-28 01.gif|thumb|The thermal night recording on January 6, 21 and 28, 2001 in the Gujarat region of India. Marked with an asterisk is the epicenter of the Bhuj earthquake on January 26 that was of 7.9 magnitude. The intermediate recording reveals a thermal anomaly on January 21 which is shown in red. In the next recording, 2 days after the earthquake, the thermal anomaly has disappeared.]]
One way of detecting the mobility of tectonic stresses is to detect locally elevated [[temperature]]s on the surface of the crust measured by [[satellite]]s. During the evaluation process, the background of daily variation and [[noise]] due to atmospheric disturbances and human activities are removed before visualizing the concentration of trends in the wider area of a fault. This method has been experimentally applied since 1995.<ref>{{Harvnb|Filizzola|Pergola|Pietrapertosa|Tramutoli|2004}}.</ref><ref>{{Harvnb|Lisi|Filizzola|Genzano|Grimaldi|2010}}.</ref><ref>{{Harvnb|Pergola|Aliano|Coviello|Filizzola|2010}}.</ref><ref>{{Harvnb|Genzano|Aliano|Corrado|Filizzola|2009}}.</ref>

In a newer approach to explain the phenomenon, [[NASA]]'s Friedmann Freund has proposed that the [[Infrared|infrared radiation]] captured by the satellites is not due to a real increase in the surface temperature of the crust. According to this version the emission is a result of the quantum excitation that occurs at the chemical re-bonding of [[Electric charge|positive charge]] carriers ([[Electron hole|holes]]) which are traveling from the deepest layers to the surface of the crust at a speed of 200 meters per second. The electric charge arises as a result of increasing tectonic stresses as the time of the earthquake approaches. This emission extends superficially up to 500 x 500 square kilometers for very large events and stops almost immediately after the earthquake.<ref>{{Harvnb|Freund|2010}}.</ref>