Interview with Prof. Dr. Panayiotis A. Varotsos—Winner of the Geosciences 2024 Best Paper Award
All papers published in 2024 in Geosciences (ISSN: 2076-3263) were considered for the award. After a thorough evaluation of the originality and significance of the papers, citations, and downloads, the winner was selected.
“Improving the Estimation of the Occurrence Time of an Impending Major Earthquake Using the Entropy Change of Seismicity in Natural Time Analysis”
by Panayiotis A. Varotsos, Nicholas V. Sarlis, Efthimios S. Skordas, Toshiyasu Nagao, Masashi Kamogawa, E. Leticia Flores-Márquez, Alejandro Ramírez-Rojas and Jennifer Perez-Oregon
Geosciences 2023, 13(8), 222; https://doi.org/10.3390/geosciences13080222
The winners will receive CHF 500 and a chance to publish a paper free of charge after peer review in Geosciences in 2025.
The following is an interview with Prof. Dr. Panayiotis A. Varotsos:
1. Could you give us a brief introduction of yourself to the readers?
I am an Emeritus Professor at the National and Kapodistrian University of Athens, Greece. Since the 1970s, I have focused on the dielectric properties of solids including several rocks, and I have established a rigorous foundation of the thermodynamic parameters that govern the formation and/or migration of defects in solids. In the early 1980s, I found that the presence of aliovalent impurities in ionic solids results in the formation of extrinsic defects, forming electric dipoles—the relaxation time of which depends on pressure (stress). I also showed that when the pressure reaches a critical value, σcr, a cooperative orientation of these dipoles may occur, which results in the emission of a transient electric signal. This may happen before an earthquake (critical point) since the stress gradually increases in the focal region before the rupture. These signals are termed Seismic Electric Signals (SESs) and have been experimentally detected since 1981, providing information on the magnitude and the epicenter location of a forthcoming earthquake. Such signals have been observed on many occasions in Greece and other countries. Moreover, in 2001, a new concept of time, termed natural time, was introduced, the analysis of which enables the study of the dynamical evolution of a complex system and identifies when the system approaches a dynamic phase transition. Such a transition is a major earthquake occurrence.
I have authored or co-authored about 300 publications and five monographs.
Photo 1. At the beginning of the 1970s and 1980s, Prof. Dr. Varotsos established the foundation of the thermodynamic parameters governing the formation and/or migration of defects in solids, which reveal that a series of transient electric signals (termed SES activity) should be emitted and when the critical point is approached a major earthquake is impending.
2. Could you briefly summarize the key findings or contributions of your award-winning paper?
A new procedure is presented concerning a more accurate identification of the occurrence time of an impending major earthquake by combining the entropy change in natural time under time reversal and the non-additive Tsallis entropy. A shortening of the time window of the impending mainshock is achieved for large events in Japan, Mexico, and California. Specifically, the time of occurrence is almost one day before the 2011 M9 Tohoku mega-earthquake, which is the largest event ever recorded in Japan; a comparable shortening to earthquakes of smaller magnitude of the order of M8 and M7 is achieved. Namely, the Chiapas M8.2 earthquake (which is Mexico’s largest event for more than a century, which took place on 7 September 2017 near the coast of Chiapas state Mexico), the 19 September 2017 M7.1 earthquake that occurred within the Mexican flat slab, and the M7.1 Ridgecrest on 6 July 2019 in California.
3. What inspired you to pursue this particular research topic?
Upon studying the seismicity in a region for a time period during which a major earthquake may occur, the superiority of the entropy changes in natural time under time reversal compared to the non-additive Tsallis entropy has been identified. The change in natural time under time reversal exhibits a unique minimum, while Tsallis non-additive entropy may exhibit several minima. The combination of the two entropies is achieved, in accordance with the aim of our paper.
Photo 2. In the 2000s, Prof. Dr. P. Varotsos in the central laboratory explains to his co-workers that an SES activity has just been emitted (printed on a multiple recorder just behind him), which -upon applying natural time analysis- shows that a major earthquake is impending.
4. What were the biggest challenges you faced during this research, and how did you overcome them?
The minimum of the entropy change in natural time under time reversal is accompanied by an evident increase in the complexity measure that quantifies these fluctuations. This minimum can, therefore, be uniquely distinguished as a precursor of an impending major earthquake. This was challenging because the problem had to be expressed appropriately to achieve these properties.
5. How does it feel to receive the Best Paper Award, and what does this recognition mean to you?
We feel that this award may serve as a recognition of our many decades of research efforts on earthquake prediction research. Moreover, this award shows that as time goes by, more scientists and seismologists are interested in earthquake prediction.
6. What appealed to you about the journal that made you want to submit your paper? What benefits do you think authors can gain when publishing their articles in Geosciences?
Geosciences is an appropriate journal for the publication of our research efforts. The open access format of Geosciences, as well as social media sharing, contribute to disseminating our work to a wide audience of interested researchers.
7. Can you talk about your feelings about manuscript processing when submitting to Geosciences?
Our experience submitting to Geosciences was very positive.
8. Who would you like to thank for helping you achieve Best Paper?
Some of the results described in the present paper have been obtained under the guidance of the Academician Seiya Uyeda, to the memory of which this paper is dedicated.
9. What are the next steps for this research? Are there any follow-up studies or applications you plan to pursue?
There exist several next steps for this research; for example, a further improvement of shortening the time window of an impending major earthquake, as well as applying this method to earthquakes in other areas, e.g., in Taiwan.
10. What advice would you give to young researchers who aspire to produce high-impact work like yours?
We would advise young researchers that in order to achieve very good results, several decades of research efforts may be needed. Hence, they should continue pursuing their research goals no matter how difficult this might be.
11. What do you think makes a paper stand out in a competitive environment like this?
In order to make a paper stand out in a competitive environment, several years of effort may be needed. This paper applies the achievements we made throughout these years to very important and destructive earthquakes. Its ability to be practically implemented for earthquake prediction is also an additional important factor.
12. Do you have any suggestions for how we can improve the Best Paper Award competition in the future?
The best paper award could be followed by a teleconference on topics related to papers that received the award.