As it is well known, various types of anomalies occur before earthquakes. There is no successful method of earthquake forecasting as to approximate time and place using radon gas release, the alteration of water level in wells, the changes in GPS measurements or by considering various other changes. However, the study utilizing has significant differences.
1) As an example; even though the distance changes between two points on earth can be measured by the GPS method, designation of which threshold level of increase will produce an earthquake at that location is still uncertain. It is possible to make short and middle term risk analysis by only taking the speed and the total amount of increase into account. Although radon gas release can be observed before some earthquakes it does not give a clear indication of earthquake prediction as it is not known for sure which level of gas release at what point. Moreover, radon gas release can be observed before one earthquake but it might not be seen before another earthquake at the same location. In our project the differentiation does not consider very low frequency component of the electric field strength going above a threshold value, but instead focuses on extraordinary drops not seen in the normal course of a day, the sign changes of derivative of the envelope (Mov. Avg.) a limited time before an earthquake. This case was observed during Mb 6 and stronger earthquakes at the beginning of the project when there was no continuous computer recording. The record before the November 11, 1999 earthquake can be seen below and the net decrease phase is more than 1200 units from the starting point of the drop. In November 12, 1999 when there was a power failure for a longer time than a UPS can feed, decrease exceeded 1800 units before the earthquake. The automatic zooming feature of the graphics has to be taken into account when there are small changes, these kind of graphics which show similar patterns with the example below, need to be redrawn using the same scale and their ineffectiveness will be more evident. There is no example of past measurements when there was this great of a change but no occurrence of widely-felt earthquake.
2) Nevertheless, a few stations have been installed using personal resources. Abnormal changes registered are not (as of yet) sufficient to provide criteria for the magnitude of the probable approaching earthquake. Earthquakes that can be perceived without the aid of a seismograph have occasionally followed even smaller changes. Thus, the data collected cannot yet be used for an early earthquake warning in a specific area. Although this is not a 100% guaranteed solution, by increasing the number of stations and standardization of stations, we seek to collect higher quality data. We should not forget the high price we have paid, and pre-earthquake preparations should continue steadily in parallel with rapid development of projects such as this. Pre-notification of a destructive earthquake is more important in Turkey than in the United States or Japan where the construction materials are adequate to withstand eartyhquakes. In these countries, people living in earthquake prone areas do not regard their homes as potential coffins. Even high magnitude earthquakes in Turkey have shallow epicenters (< 20 km), thus pre-earthquake surface effects are augmented. In this regard, it is wrong to limit ourselves and pursue the logic that; if someone else has not done it, we surely cannot do it; before displaying our best efforts or migrating to the United States and continuing such a study there. As a consequence of waiting for someone to save us and consuming what is already produced instead of producing, we periodically face economic crises. Even though the period between crises get shorter and their severity increases as years go by, we still easily forget what we have been through.
3) The aim of this project is to detect changes prior to earthquakes of especially those of magnitude Mb6 or higher. Even though smaller earthquakes may be perceived around the epicenter, they are regarded as purely experimental evaluations for this project. Earthquakes of magnitude Mb4, Mb5 are evaluated mainly for the development and testing of the model, and the current stations may not provide observations sufficient to pre-notify in the case of such relatively small earthquakes.
4) Methods such as placing pressure/force sensors in wells, or placing radon gas probes at certain points can be evaluated only when extraordinary changes occur at the very spot where such probes are placed. Yet the earth’s crust is neither homogenous nor are its shape and structure completely known to us, so that similar signs to do not appear at the same spots prior to every earthquake. The method employed in our research project focuses on measuring an electrical value, where changes in a particular source can be measured at different points (though reduced).
Theoretical Aspects and References