 eEQP-2024: eEQP-LinkedIn-4-Tsutsui Method |
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Earthquake Prediction (EQP) Research Based on the TRIZ Philosophy: |
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Toru Nakagawa (Emeritus Professor, Osaka Gakuin University） |
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Posted: Aug. 31, 2024 |
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Editor's Note (Toru Nakagawa, Aug. 31, 2024)
This is the 5th part of my series of introductory articles posted on LinkedIn.
This is an introduction to a paper presented by Makoto Kamiyama (Professor Emeritus, Tohoku Institute of Technology) and others at the Japan Society for Earthquake Prediction (December 2023). It uses the location information of approximately 1,300 reference points nationwide, which is measured precisely and updated daily by the Geospatial Information Authority of Japan using the DNSS positioning satellite. The maximum shear strain and area strain (expansion) coefficient for each triangular area are derived by analyzing the data using the triangulation mesh method, but the latter is probably easier to understand. The paper reports detailed data and analysis results for three earthquakes, and here we have taken up the Hokkaido Eastern Iburi Earthquake (September 6, 2018, MJ 6.5). We focused on four triangular areas near the epicenter and plotted their area expansion coefficients for the 12 years from 2011. All four triangular areas initially shrank at the same slow rate, but when the earthquake occurred, two of the triangular areas suddenly expanded, and after the earthquake, they all shrank at the same slow rate as before. If we expand the time axis for the year 2018 we can see that abnormal fluctuations suddenly appeared three months before the earthquake. The two areas fluctuated in the positive direction, while the other two fluctuated in the negative direction, but if we ignore the direction, the fluctuation patterns are almost the same. The fluctuation values began to increase three months before the earthquake, peaked, then slowly decreased in an unstable manner, the earthquake occurred and the values changed suddenly, and after a few days of fine-tuning, the abnormal fluctuations disappeared.
Similar abnormal fluctuations were observed in the three earthquakes as precursory phenomena. Using these precursory phenomena, it is possible to estimate the epicentral region and magnitude of the earthquake to be predicted based on the number and extent of the regions where abnormal fluctuations are observed. As for the time of the earthquake, there is currently a margin of several years to several months, and no clues have yet been obtained to determine the imminence of the earthquake. It is hoped that more cases will be accumulated in the future. Kamiyama's method is currently considered to be the most useful and promising method for short-term (several years to several months) earthquake prediction.
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Earthquake Prediction (EQP) Research Based on the TRIZ Philosophy:
(4) Tsutsui Method: Observing Underground DC Electric Field
[Click the figure to enlarge further.]
Now I would like to introduce you to the excellent work of Professor Emeritus Minoru Tsutsui of Kyoto Sangyo University. He has been working on detecting the electromagnetic effects of earthquakes (EQs) since 1998 (and continuing after his retirement in 2015). His report at the EPSJ Conference in Dec. 2022 (in Japanese) is remarkable:
Top figure (a) shows his equipment for observing the DC electric field deep underground. He chose his site on a small island near the southern tip of the Kii Peninsula (i.e., on the Pacific coast far south of Kyoto) to avoid natural and artificial noise. He made a borehole 20 cm in diameter and 150 m deep to place a 100 m long dipole DC electric sensor. A differential amplifier is placed underground, and a 60 Hz notch filter (to remove power supply frequencies) and a low-pass filter are placed on the ground. The signals are sampled every second and recorded on a PC. In addition, two 5 m long sensors are installed 8 m above the ground to monitor the horizontal electric field (EW and NS).
The equipment operated from April to July 2021 and provided valuable observational data in two forms:
Fig. (b) shows the signals observed on May 1, 2021, with drastic (±) variations with S/N over 30 for 46 minutes from 08:50, a sharp spark at 10:27, and the second drastic variations for 68 minutes from 19:00. He later learned that an EQ occurred at the same time (10:27) with M6.8 at a depth of 50 km, off the coast of Miyagi Prefecture (about 750 km away). He sees the first drastic variation as a precursor to the 10:27 EQ and the second drastic variation (most likely) as a "post-cursor". The horizontal electric field sensors on the ground observed similar fluctuations in both the EW and SN directions during the two periods of variation mentioned above, even though the signals were superimposed by gradual fluctuations caused by diurnal changes in the ionospheric electric field.
Fig. (c) shows the signals observed on May 6, 2021. The mean electric field rose slowly from 0 to +2 μV/m (with S/N about 4) at 05:25, lasted about 5 hours, dropped to nearly 0 and remained there for about 3 hours, then suddenly jumped to +2μV/m at 13:30 and then returned (with some minor fluctuations) to 0 potential in about 6 hours. He later learned that an EQ occurred at 13:30 with M3.7 at a depth of 50 km in the Kii channel (about 100 km away). (The horizontal electric field sensors above ground showed gradual noisy fluctuations during the day to hide any information corresponding to the underground data).
We are convinced that these two forms of observed data are related to the occurrence of EQs as precursors to them and that this method is precious for detecting EQs occurring far away under the land or sea, with signals of high S/N and fine structures covering the time from several hours before to several hours after the EQ. Therefore, I propose to initiate a collaborative research project within EPSJ to establish a Short-term/Imminent EQ Prediction Method based on the Tsutsui Method.
Stage (1) We should support him in solving his various difficulties, such as maintaining his equipment including the PC which was once hacked and once crashed, installing a data transfer system from his remote site to his home PC, etc. He has rich experimental know-how and unpublished observational data since 2021, which may show different signal patterns reflecting different EQ processes.
Stage (2) Collaborative project with multiple observing sites operating in parallel. Our tasks are:
(a) Set up multiple observing sites and operate them in parallel. Review the records from all the sites together and distinguish signals from noise.
(b) Compare the observation data with the published records of EQs to distinguish the cases of Correlation, Non-correlation, and No-observation, and to reveal the correlation of (some patterns of) variation of the underground DC electric field with (some types of) EQs.
(c) Develop a method for estimating the time, place, and magnitude of impending EQs. Note: The transmission speed of the electric field through the lithosphere is about half the speed of light. Therefore, we cannot use the usual method of estimating the location of the epicenter by using the time differences of receiving the EQ signals in the form of P-waves (with the speed of 7 km/s) at 3 (or more) different locations. We need some additional information, such as the incoming direction of the signals.
(d) Test the (in-advance) estimation method to see how well the prediction agrees with the EQs that occurred shortly afterward, and refine the prediction method.
To start this project we need discussions within EPSJ and get the second and several more research groups to decide to seriously work on this research project. Technical problems are to build boreholes in remote, noiseless locations and to build a network system to upload the observation data from all sites and to analyze them in a project center and each group. Obviously, we need a project organization to decide/guide the research strategy, raise some funding, and promote the project to the academic community.
Stage (3) as a Technical Method for EQ Prediction: If our prediction method successfully passes Stage (2), we will deploy our method/system on a national scale. We will build several tens of observation sites all over Japan, operate them in an automatic/stable/reliable manner to form a network system, watch for (significant) EQs that may occur at any place at any time, and get ready to predict (possible) impending EQs to alert within the project. We should establish a research project based on EPSJ, with many research groups, and officially supported by academia (especially SSJ) and government agencies. The practical usefulness and reliability of an EQ prediction method can only be revealed at this stage.
We need to proceed further to Stage (4) A complete technology system of EQ prediction (by integrating complementary methods) and Stage (5) Official operation of Short-term/Imminent EQ Prediction Alert (by obtaining understanding and approval from academia, society, and government). I will discuss them later, after introducing to you two other EQ prediction methods.
Book Review Yoshida |
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EQP: Japan TRIZ Sympo |
jEQP 2024 Index |
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Nakagawa Presentation (EPSJ 2023) |
EQP 2023 Index Page |
Last updated on Aug. 31, 2024. Access point: Editor: nakagawa@ogu.ac.jp
