On the reported ionospheric precursor of the 1999 Hector Mine, California earthquake

Abstract

Using Global Positioning System (GPS) data from sites near the 16 Oct. 1999 Hector Mine, California earthquake, Pulinets et al. (2007) identified anomalous changes in the ionospheric total electron content (TEC) starting one week prior to the earthquake. Pulinets (2007) suggested that precursory phenomena of this type could be useful for predicting earthquakes. On the other hand, and in a separate analysis, Afraimovich et al. (2004) concluded that TEC variations near the epicenter were controlled by solar and geomagnetic activity that were unrelated to the earthquake. In an investigation of these very different results, we examine TEC time series of long duration from GPS stations near and far from the epicenter of the Hector Mine earthquake, and long before and long after the earthquake. While we can reproduce the essential time series results of Pulinets et al., we find that the signal they identified as being anomalous is not actually anomalous. Instead, it is just part of normal global‐scale TEC variation. We conclude that the TEC anomaly reported by Pulinets et al. is unrelated to the Hector Mine earthquake.

Brief communication "Further comments on the ionospheric precursor of the 1999 Hector Mine earthquake"

“…They show that the TEC changes documented by Pulinets et al (2007) are not anomalous but normal variations on global scale, and, therefore, these changes are not related to the localised seismic activity of the Hector Mine area. This paper confirms the results of Afraimovich et al (2004) and Thomas et al (2012). Through the use of geomagnetic indices time series it is shown that the presumed precursor of Pulinets et al (2007) was a normal TEC variation induced by solar-terrestrial interaction.…”

“…In a previous paper, Afraimovich et al (2004) excluded that TEC variations, which occurred before the Hector Mine earthquake, were induced by the preparation process of the seismic event. Thomas et al (2012) reach similar conclusions by performing new analyses of the same TEC data which were investigated by Pulinets et al (2007). They show that the TEC changes documented by Pulinets et al (2007) are not anomalous but normal variations on global scale, and, therefore, these changes are not related to the localised seismic activity of the Hector Mine area.…”

“…As Thomas et al (2012) point out, such similar studies to Pulinets et al (2007) motivate the idea that earthquake prediction will one day be possible. Earthquake prediction is a controversial challenge of the scientific community but it has also a social importance because of the great benefit that could be obtained with accurate predictions.…”

On the multi-fractal characteristics of the ULF geomagnetic field before the 1993 Guam earthquake

“…The authors document seismogenic changes in the multi-fractal parameters of the geomagnetic field H component starting about one month before the earthquake. As Thomas et al (2012) emphasize, these kinds of reports have motivated many researchers to study in depth the possible occurrence of earthquake precursors as well as to develop physical models to explain their generation. Thus, the results of these publications must be carefully checked.…”

“…However, since previous studies do not show strong evidence of correlation between the presumed magnetic precursors and seismic events, many scientists do not agree that these signals are really related to the earthquake occurrence. As a consequence, these researchers seriously put into question previous observations of magnetic ULF earthquake precursors and have published their findings (see Campbell, 2009;Masci, 2010Masci, , 2011aMasci, , b, 2012aThomas et al, 2009a, b) giving rise to an intense re-examination process of controversial scientific claims (see also Fraser-Smith et al, 2011;Masci, 2012d;Thomas et al, 2012).…”