The Great Hanshin and Awaji Earthquake (M7.3, Max. seismic intensity level 7) occurred on January 17, 1995, with the focus of the epicenter located in Hyogo Prefecture. Many buildings including highways were destroyed, and its devastating damage claimed more than 6,000 lives. This earthquake made us realize that even in regions where the predicted occurrence rate was extremely low, there is always the possibility of massive earthquakes that can bring about vast and serious damage.
Immediately after the big earthquake in February 1995, our company hosted an inter-industry event. During this meeting, many cases of “Noise in radio waves” were brought up, such as an atomic clock that had become inaccurate just before the earthquake occurred, a driver who was on the Hanshin Expressway had complained about the noise on his AM radio, etc. Also, there was an introduction to a research paper written by a Japanese seismologist about “Electromagnetic anomalies for earthquake predictions,” which was published in an English Journal, “Nature vol.347, No.6291, Sept.1990.”
According to the research paper, electromagnetic radiation waves were released from minerals by an increase in underground pressure before large earthquakes. Collecting and observing these electromagnetic signals might allow us to predict the time when earthquakes are about to happen.
The members of the inter-industry group, mainly consisting of engineers, visited the seismologist’s office immediately after reading the article, and they started the research on earthquake predictions that uses electromagnetic signals after concluding an agreement to receive technical support from the seismologist.
You must have encountered a situation in which your radio transmission got interrupted by noise when there was a thunderstorm. That noise actually is what the electromagnetic signals sound like.
This electromagnetic noise could easily be detected if there was an open frequency that is not occupied for radio broadcasting or wireless communications. Unfortunately, most of the frequencies are currently used for some kind of broadcasting or communications. Although humans can detect the difference between the artificial signals and the electromagnetic noise that is an earthquake precursor, it is extremely difficult to automatically identify them.
The “Reverse Radio” equipment, which is developed by our company, automatically identifies natural electromagnetic noise and separates it from other noise from an artificial origin such as broadcasting and communications by canceling them. We acquired a patent in 2001.
After that, our company developed a higher-accuracy reverse radio system, which allowed the steady collection of electromagnetic noise from the observation points throughout Japan. We also succeeded in finding a correlation between past earthquake occurrences and electromagnetic noise data. The statistical analysis of the data allowed us to perform more accurate earthquake predictions.
Currently, our company releases weekly earthquake predictions in Japan, with an accuracy rate of 70-80%.
Why is electromagnetic noise released before earthquakes? It is necessary to destroy rocks to find out how strong the electromagnetic noise can be as an experiment, just so we can create the same conditions of an earthquake. Many researchers all over the world did experiments on destroying rocks, but here is one example of such an experiment conducted by Dr. Shingo Yoshida of Tokyo University shown in the figure below called “Saturated sandstone compression experiment data.”
When a saturated sandstone specimen with a diameter of 4 cm and a length of 10 cm was pressurized, 0.1 - 0.3 V of electric voltage was generated just before the specimen ruptured. The research indicated that saturated, quartz-free basalt also produced 1/10 of the electric voltage stated above, due to water movement. When a 10 cm-long rock specimen produces 0.1 V of electric voltage, a rock that is 10 km by 10 km in size would produce 10,000 V of electric voltage.
Of course, electric voltage is only produced when the amount of pressure applied to the sandstone increases. If the pressure remains at a fixed level, even if the level is high, the electrical charges will not be produced.
A 10 cm sample produces 0.1 volt → When the pressurized area is 10 km before an earthquake, 10,000 volts will be produced!
According to experiments conducted by other researchers than the one mentioned above, there is a strong correlation between micro cracks (destruction/deformation of micro molecular structure) in the rocks getting filled with increasing pressure and water movements with an electric current produced concurrently.
If this is the case, if all the cracks are filled and the water gets pushed out, it will not be able to go any further and it is quite possible that no electric voltage will be produced even when more pressure is applied.
In reality, the trends in which the amount of noise detected on Reverse Radio show that most of the earthquakes occurred after the amount of noise that gradually increased every day reached the peak, started to decline and then became hardly undetectable (called settlement of data). Most cases show that fault planes moved after the settlement causing earthquakes. Because of this, the total amount of noise before and after the peak is considered proportional to the size of the entire rocks on which pressure is applied. This allows us to estimate the magnitude of the earthquake that is about to occur, and depending on the situation with the settlement of data, it is highly possible that its timing can also be predicted.
Although many seismologists who study earthquake predictions use earth currents and electromagnetic signals, false detections are also very common. Artificial frequencies/electromagnetic signals such as trains can alternate earth currents, and broadcasting and communications could interfere with the signals.
By developing the “Reverse Radio” system, our company succeeded in canceling signal waves that are created by broadcasting transmissions and in only extracting natural electromagnetic noise. This allowed us to make the most of earthquake predictions highly successful.
Currently, our company releases weekly earthquake predictions throughout the country, with an accuracy rate of 70-80%.
The inter-industry group including our company developed the unique “Reverse Radio” device that automatically identifies natural electromagnetic noise to pursue our studies in earthquake prediction. The group acquired a patent for the system in 2001.
Electromagnetic noise detector/analyzer
(Many overseas patents based on Patent No. 3188609, No. 5379373)
<Configuration>
Reverse Radio main unit: 1, controller: 1, special cable: 1 (5 m), Power supply unit: 1, LAN cable: 1 (1.5m)
<Specifications>
Reverse Radio main unit: Basic frequency reception: 850 kHz
<Reverse Radio Features>
The figure below shows how AM radio band broadcasts modulate high-frequency carrier waves to produce audio signals (Fig. A), but occasionally pulse noise generated by the earth’s currents can interfere with the transmission (Fig. B).
As shown in Figure C, when these signals that are received on radio and audio signals are played normally by detecting and amplifying low frequencies, they can be played without any noise as they don't contain any high-frequency pulse noises.
On the contrary, when high-frequency signals are detected and amplified as high frequencies, although the envelope of the signals are the same as those of audio signals, the high-frequency pulse noise remains as is.
When the waveforms are extracted from the audio signals, most of the audio signals are canceled, leaving the high-frequency pulse noise more prominent. The amount of pulse noise remaining will be measured.
Because this Reverse Radio outputs only the noise instead of audio signals as regular radios do, we named it a “Reverse Radio.”
The development group of the earthquake prediction system that measures the electromagnetic signals using Reverse Radio has studied the correlation between anomalies in electromagnetic noise and earthquake occurrences for approx. 20 years.
As a result of our studies, it became clear that abnormal electromagnetic noise was observed just before an earthquake and that there was a strong correlation between earthquakes and electromagnetic noise.
Furthermore, the amount of electromagnetic noise was unexpectedly large as an earthquake precursor.
In other words, a massive amount of electromagnetic noise is produced for a long period of time before a large earthquake. The scale of the earthquake can be projected based on the data size, the epicenter can be guessed based on the data location, and the approximate date of the occurrence can be predicted based on the damping and settlement of the noise data.