Stochastic relation between anomalous propagation in the line-of-sight VHF radio band and occurrences of earthquakes

This paper was intended to find out any relation between anomalous line-of-sight propagation on the very high frequency (VHF) band and occurrences of earthquakes near the VHF propagation paths. The television and FM radio broadcasting waves on the VHF band were monitored continuously over the long term. For that purpose, a multidirectional VHF band monitoring system was established and utilized. Anomalous line-of-sight propagation on the VHF band was distinguished from the monitored wave by using a statistical analysis. After the stochastic consideration, it was found out that earthquakes associated with anomalous propagation were characterized by magnitude of earthquakes M ≥ 4.5, and distances from epicenters L ≤ 75 km. The anomalous propagation was monitored on the VHF band a few days before the associated earthquakes occurred. Moreover, the anomaly appeared on multidirectional propagation paths simultaneously. The anomaly on the line-of-sight propagation indicates the possibility of narrowly focusing the area of the epicenter of earthquake.

Comment 2: The authors use the equation for unrelated probability P unrel (t per ) estimation without any basis comments or references on its validity, page 6835, line 11.It is important because the using the other equations for statistic of two unrelated occurrences: anomalous propagations (1) and earthquakes (2) would bring to the probability P unrel dependence not only on the defined length of time t per , page 6835, line 16, but on the number of occurrences N anom and number of earthquakes N eq too.The results of calculations may differ from the obtained in the paper.

Authors' answer:
The equation of the probability P unrel , page 6835, line 11, is original.However, it can be obtained by using basic probability theory, as follows.
Let's consider that only one anomaly and only one earthquake occurs under no relation during the entire observing period, T all .When earthquake occurs within defined length of time period t per after the anomaly, we consider that the earthquake is associated with anomaly.
At first, we derive a probability of NOT sequential occurrence of both in defined time period t per ,   Observing period all T Therefore, the  When the wind velocity was 3 m/s or more at Kumagaya observatory, anomalous propagation was not monitored at all.Although an anomalous propagation happened to appear under no wind condition, it disappeared with increasing the wind velocity.
The number of earthquakes that happened after anomalous VHF propagation occurrences was four for t per = 2 days, it corresponded to the number N obs = 4 for The other hand, no earthquake happened before anomalous VHF propagation occurrences for same t per .
Short descriptions about the relationship to surface wind velocity and the number of earthquakes that happened before and after anomalies are added into the revised paper.

Authors' answer:
Answer for comment 4 is same explanation for comment 1.
Comment 5: The presented review on the electromagnetic phenomena associated with seismicity (1 Introduction) would be more valuable if earlier investigations in this field were mentioned, for example: . . . . . . . . . . . .

Authors' answer:
We understood your comment.We missed some earlier investigations, therefore, we add a reference as follows to the revised paper.
Comment 6: The References (page 6839, line 4-21) require checking and correction in author's names and journal title.
Authors' answer: Thank you for pointing out mistakes in References.We checked the references and corrected mistakes.Moreover, we changed the difficult-to-get references for readers to easily-obtainable other papers.Therefore, we modify the references as follows in the revised paper.
Authors' answer: Thank you pointing out some wrong expressions.We checked expressions and correct in the revised paper.

Appendix
List of local time, means (m), m plus 3 standard deviations ( ) and m minus 3 of 5-minute time slots in Fig. 3(b) ( VHF TV broadcasting wave: TV Asahi, f=205.25MHz )

.
To simplify, time of occurrence of anomaly is fixed, a black up-pointing allow as below figureof occurrence of earthquake at complementary time period, indicated in red lines as following figure.

Authors' answer :
We had considered the relation between the anomalous VHF radio propagation and the atmospheric phenomena.Until now, we have no clear statistical results which indicate existence of the relation between both.However, we have noticed an empirical relation between anomalous VHF radio wave propagation and surface wind velocity near the propagation path.We investigated the weather data of Kumagaya local meteorological observatory, which located near the propagation path from Tokyo-tower to Kiryu monitoring point.It is located 64km from Tokyo-tower.

Comment 4 :
The authors have to explain or present more correct data imaging on the Figures (Fig. 3, 5 and 6): 72 mean values (m) and 72 standard deviations ( ) in every day yield 20 minutes digitization.Why more detail temporal evolutions are shown on the Figures.
. Because it is the conditional probability that first earthquake occurs out of t per and second earthquake occurs out of t per too.
eq times earthquakes.For each anomaly the probability   per unrel t P is same, therefore, the   per unrel t P is the probability that earthquakes just happen to occur after one anomaly sequentially in a defined time period t per under no relation.On the other hand, the probability   per obs t P , page 6835, line 20, is the observational probability.It is obtained as the number of occurrences of anomalies associated with earthquakes divided by the number of all anomalies.It means the   are the probability for each anomaly.Therefore, the number of occurrences of anomalies, N anom , is not included in the equation of the probability P unrel , page 6835, line 11.Short description of the above explanation is added into the revised paper.Comment 3: The author should comment or show any data on the weather observation during occurrences of anomalous VHF radio wave propagation.Was there connection between the recorded anomalies and the atmospheric phenomena?It is necessary to give the exact number of earthquakes that happened before and after anomalous VHF propagation occurrences, ("before" is included to running paper title).