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A PRELIMINARY REPORT OF VERY LOW FREQUENCY ANOMALY IN VTX-MALDA and
VTX-SITAPUR PROPAGATION PATHS BEFORE THE NEPAL-7.4M EARTHQUAKE ON 12-52015
Sandip K. Chakrabarti, Asit K. Choudhury, Bakul Das, Sudipta Sasmal, Soujan Ghosh
We have been monitoring VLF signals from VTX station (17KHz) from two of our receivers: MALDA
and IERC/ICSP located at SITAPUR.
Fig. 1 shows the size of the preparation zone which overlaps with the propagation path from VTX
transmitter to MALDA and SITAPUR receivers.
Fig 2a: The VLF signal showing significant anomalies up to 5 days before the earthquake. There was no
anomaly in sunset terminators. DLDP/DLPT at Sunrise and Sunrise terminator was shifted.
Fig. 2b shows the data from IERC/ICSP Sitapur campus.
What we observe is that there is significant Signal anomaly in VLF since 7th May, 2015, at least five days
prior to the earthquake. This is consistent with our reports in previous papers. The signals at Sitapur is
different from that of Malda in that Night time fluctuation two days prior to the E/Q was also seen. No
DLPT/DLDT was anomalous in Sitapur data. There are constructive and destructive interferences on the
propagation path and thus the signal is affected. These are being analysed and will be reported elsewhere
(in preparation).
Fig. 3a shows the anomalous sunrise Terminator shift in the JJI (Japan) to Sitapur (IERC/ICSP)
propagation path.
Fig. 3b shows the anomalous sunset Terminator shift in the JI (Japan) to Sitapur (IERC/ICSP) propagation
path. Note that the terminator shifts on the 9th (3 days)
Shift in SRT is 18.5 minutes (3 days before). Shift in SST 16 minutes (2 days before).
Fig. 4 shows the propagation paths from all the major receivers to IERC/ICSP.
Predictions: based on the fact that night time fluctuations are found to be maximum at least three days
before an earthquake, we think there could be major E/Qs aftershocks till 14th May night.
This site will be updated if the anomaly persists from now on.
Updated on 13th May 10am:
We update the data obtained from VTX at Malda (Fig. 5a) and Sitapur (Fig. 5b) sites:
Observation: No significant anomaly in Sitapur data on SRT, but nighttime amplitude change between the
nights of 12 and 13th remain very high. Significant Night time fluctuation also observed at Malda data. It
also shows several minutes of SRT shift towards night.
Conclusion: The anomaly persists significantly. Further major earthquake (>6.0M) next 72 hours
CANNOT BE RULED OUT.
Fig. 6 shows the VTX-MALDA data for last two weeks. Todays anomaly is significant in every respect.
Conclusions: Major E/Q within 1000km radius of Malda cannot be ruled out in the next 72 hours.
Fig. 7a shows the JJI-Sitapur data for the last five days:
Fig. 7a. JJI-Sitapur data showing SRT returning back to normal but with an extra destructive
interferences. A major E/Q within next 72-96 hours cannot be ruled out. We will update the sunset data
after Sunset. Today's 6.8M in Japan is also on this propagation path. So it is possible JJI signals behaviour
is due to the Japan E/Q 6.8M of 13th May, 2015.
Fig. 8. shows the NWC-Sitapur data till 13th. We clearly see a night time fluctuation in 12-13th night
similar to what we saw in 10th-11th night. This has changed the SRT as well. All these are indicative of
excess ionization in D/E/F layers within about 1000km of the receiving station. Major E/Q or aftershock
cannot be ruled out in the next 72 hours.
Fig. 8: NWC-Sitapur data showing anomalies in Nighttime during 10-11th and 12-13th nights. Probability
of a major E/Q after 72 hours is about 40-50% after such an anomaly. But probability rises to about 70%
if we consider it to be precursor seven days ahead.
Caveat: We require several antennas to pinpoint the epicentre. However, general disturbances in the D/E/F
layers could be seen.
Updated on 14th May, Morning:
Fig. 9: The sunrise terminator is still anomalous. A major earthquake in next 72 hours alter will remain
on.
Fig. 10: Sunset termintor time of JJI-IERC path updated upto 13/05/2015 evening
Fig. 11: Sunrise terminator time of JJI-IERC path updated upto 14/05/2015 morning. The SRT is still in
anomalous stage
Fig. 12: VTX- Sitapur Signal amplitude variation updated upto 14/05/2015. Sunrise terminator is
anomalous
Fig. 13: JJI-Sitapur data showing Signal amplitude updated variation updated upto 14/05/2015 morning.
Fig. 14: NWC-Sitapur data showing Signal amplitude variation updated upto 14/05/2015 morning.
Prediction: Anomalous sunrise terminators and nighttime fluctuation in JJI and VTX signal. Possibilities
of earthqaukes in next 72 hour
Updated on 15th May, Morning:
Fig. 15: Sun Rise Terminator Time is more anomalous, Possibility of Major E/Q in next 72 hours
increases, Alert will remain on.
Fig. 16: Variation of sunrise terminator time (SRT) updated up to 15/05/2015 morning. The SRT
is again started to shift towards nighttime indicating possibilities of earthquake in next 72 hours.
Fig. 17: Variation of sunset terminator time (SST) updated up to 14/05/2015 evening. There is a
strong shift in SST towards nighttime. This is a major indication of possibilities of earthquake in next
72 hours.
Fig. 18: Variation of signal amplitude for JJI-IERC path updated up to 15/05/2015 morning. The
indication of both SRT and SST on yesterday and today’s data. This could be strong precursors of
earthquake.
Fig. 19: Variation of signal amplitude for VTX-IERC path updated up to 15/05/2015 morning. There is an
unusual nighttime fluctuation on 14/05/2011 night. This can be a precursor of earthquake.
Prediction: The JJI signal amplitude shows a strong shift of sunrise and sunset terminator times which
indicating possibilities of earthquake in next 72 hours.
Updated on 16th May, Morning:
Fig. 20: Variation of sunrise terminator time (SRT) updated up to 16/05/2015 morning. The SRT is
returning back to daytime. There is higher nighttime fluctuations. The possibilities of earthquakes in next
72 hours cannot be ruled out.
Fig. 21: Variation of sunset terminator time (SST) updated up to 15/05/2015 evening. Though the SST is
returning back towards daytime but still it is in anomalous stage.
Fig. 22: Variation of signal amplitude for JJI-IERC path updated up to 16/05/2015 morning.
Fig. 23: Variation of signal amplitude for NWC-IERC path updated up to 16/05/2015 morning
Fig. 24: Variation of signal amplitude for VTX-IERC path updated up to 16/05/2015 morning. The
nighttime fluctuation on 16/05/2011 is comparatively higher. This can be a precursor of earthquake.
Predictions: The JJI signal amplitude shows anomalous value of sunset terminator times and VTX signal
shows anomalous nighttime fluctuation. Possibilities of strong earthquake in next 72 hours cannot be
ruled out..
Updated on 17th May, Morning:
We update the data obtained from VTX at Malda (Fig. 25a) and (Fig. 25b) site:
The anomaly in SRT and night time fluctuation on 15th to 17th indicates another major earthquake in next
72 hours.
Fig. 26: Variation of sunrise terminator time (SRT) updated up to 17/05/2015 morning. The SRT is
continuing to return back towards daytime.
Fig. 27: Variation of sunset terminator time (SST) updated up to 16/05/2015 evening. The SST is
continuing to return back towards daytime.
Fig. 28:Variation of signal amplitude for JJI-IERC path updated up to 17/05/2015 morning.
Fig. 29: Variation of signal amplitude for NWC-IERC path updated up to 17/05/2015 morning.
Fig. 30: Variation of signal amplitude for VTX-IERC path updated up to 17/05/2015 morning. The
nighttime fluctuation on 17/05/2011 is comparatively higher. This can be a precursor of earthquake.
Prediction: VTX signal shows anomalous nighttime fluctuation. Possibilities of earthquake in next 72
hours cannot be ruled out..
Updated on 18th May, morning:
We update the data obtained from VTX at Malda (Fig. 25a) and Sitapur (Fig. 25b) sites:
There is Anomalous Sunrise Terminator (SRT), Night Time Fluctuation (NTF) and significant shift in the
Sunset Terminator (SST). These may be precursors of major E/Q.
Fig. 32:Variation of sunrise terminator time (SRT) updated up to 18/05/2015 morning. There is a shift in
SRT of about 13 minutes.
Fig. 33: Variation of sunset terminator time (SST) updated up to 17/05/2015 evening. There is also shift in
SST of about 11 minutes.
These may be indications of some E/Qs .
Fig. 34:Variation of signal amplitude for JJI-IERC path updated up to 18/05/2015 morning.
Fig. 35: Variation of signal amplitude for NWC-IERC path updated up to 18/05/2015 morning.
Fig. 36: Variation of signal amplitude for VTX-IERC path updated up to 18/05/2015 morning.
The nighttime fluctuation on 17/05/2011 is comparatively higher. Moreover, SST of VTX on yesterday
data did not come up to the same amplitude level of SRT. The amplitude at SST is much higher than that
of other days data. This can be a precursor of earthquake.
Prediction: VTX signal shows anomalous nighttime fluctuation. Shifts in SRT and SST of the data for
path JJI-IERC is also observed. Possibilities of earthquake in next 72 hours cannot be ruled out.
Updated on 19th May, Morning:
Today's SRT is normal but night time fluctuation is there. Possibilities of E/Q cannot be ruled out.
Fig. 37: Variation of signal amplitude for NWC-IERC path updated up to 19/05/2015 morning.
Fig. 38: Variation of signal amplitude for VTX-IERC path updated up to 19/05/2015 morning.
The JJI-IERC signal is noisy. Data filtering and analysis is going on and will be uploaded soon.
Prediction: VTX signal shows anomalous nighttime fluctuation. Possibilities of earthquake in next 72
hours is still there.
Updated on 20th May, Morning:
Fig. 39: There are no anomaly in the Sun Rise Terminator, Night time amplitude, shift in the Sun Set
Terminator becoming normal. Though the alert still remain up to tomorrow.
Fig. 40 : Variation of sunset terminator time (SST) updated up to 19/05/2015 evening. There is a shift in
SST of about 10 minutes.
Fig. 41: Variation of signal amplitude for JJI-IERC path updated up to 19/05/2015.
Fig.42: Variation of signal amplitude for NWC-IERC path updated up to 19/05/2015
Fig. 43: Variation of signal amplitude for VTX-IERC path updated up to 19/05/2015.
Prediction : The shift in SST of the data for path JJI-IERC is an indication of E/Q ahead. The
possibilities are still there.
N.B. : Today morning's data is noisy. Data filtering is in progress and will be uploaded soon.
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Updated on 21th May, Morning:
Fig. 44: Data of last 48 hours look normal. However, because of
night time fluctuation on the 19th May, 2015 we
continue the alert level for another 24 hours.
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Updated on 22th May, Morning:
Fig. 45: Last 72 hours the data is normal. However, given that there was some night time anomaly just
before that, we recommend alert for another 48 hours.
Updated on 23th May, Morning:
Fig. 46: The sunset terminator of 22nd May, 2015 and the night time fluctuation is above 3 sigma level in
the night of 22nd and 23rd. We issue an alert of a major earthquake (>5M) in the next 72 hours within
1000 km of Malda station (25.00 N and 88.10 E).
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Updated on 24th May, Morning:
Fig. 47: The data is normal for last 24 hours. however alert of next 48 hour is on.
Updated on 25th May, Morning:
Fig. 48: Night time fluctuation was significant in th enight of 24th and 25th of May, 2015.
Some seismic activity in the region is expected in next 72 hours.
Updated on 26th May, Morning:
Fig. 49: Data seems normal last 36 hours. A seismic event in the next 36 hours cannot be ruled out.
Updated on 27th May, Morning:
Fig. 50: The data is normal past 60 hours. However, a chance of earthquake in the next 12 hours cannot be
ruled out
Updated on 28th May, Morning:
Fig. 50: The data looks normal for the last three days. Chances of a major E/Q around Malda receiver
(1000km radius) is small.
Updated on 29th May, Morning:
Fig. 51: There are no anomalies in the last five days. The chance of major earthquakes in the 72 hours in
the region around Malda is low.
Updated on 30th May, Morning:
Fig. 52: The data is normal. No major seismic activity is expected next 72 hours.
Updated on 31st May, Morning:
Fig. 53: Appears to be normal. Chance of major EQ within 1000km radius around Malda is unlikely.
Updated on 2nd June, Morning:
Fig. 54: The data appears to be normal. No Earthquake is expected in the region next 24-72 hours.
Updated on 3rd June, Morning:
Fig. 55: The data appears to be normal. No Earthquake is expected in the region next 24-72 hours.
Updated on 4th June, Morning:
Fig. 56: Large isolated night time fluctuation in the night of the 3rd and 4th June, 2015. A moderate
seismic event is possible in the next 48 hours.
Updated on 12th June Morning:
Fig. 57: Chance of a major EQ next 72 hours likely.
Updated on 13th June Morning:
Fig. 58: Chance of a major EQ next 72 hours likely.
Sandip K.Chakrabarti, Asit K. Choudhury, Bakul Das, Sudipta Sasmal, Soujan Ghosh ICSP
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