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 Turkey  08/17/99  

Mexico  06/15/1999


These pages indicate the detection times of recent earthquake precursors, as recorded by the Elfrad Group

12/09/2001 0.02N 123.01E Depth 155.5 Km M=5.5 Minahassa Peninsula, Sulawesi

An event has occurred in Indonesia which had an unusually high precursor indication. The graph below shows the raw data recorded at 4.1 CPS before processing. This is a  24 hour chart starting at 00:00 12/09/2001. Another earthquake was also recorded an hour later in the Bonin Islands, Japan region at 19:19:52 UTC.  The coordinates of this additional event were 28:14N 139.23E with a magnitude of 4.6. The depth was deeper than usual at 508.8 km. It is suspected that both precursors from both events are depicted on the following graphs.

The next graph indicates the duration of the precursor. Beginning at 07:09:09 and ending at 18:14:19 UTC. The "P" indicator is the start time at 07:09:09 and the "S" indicator is the time of the Minahassa quake. The activity to the right of the "S" indicator shows the time  of the Bonin event. The duration of the precursor detection was 665 minutes.

The photo below shows the Earth's DC level fluctuations. It is normal during a 24 hour period to have slight changes in the DC level of the earth, however during the time period preceding  this most unusual event, the surface voltage dropped  4000 units below normal and then rose to 3000 units above normal. This may indicate a change in surface voltage caused by the precursor emissions. The abrupt changes were noticeable 268 minutes before the quake.

 The next graph is an FFT spectrum analysis of this time period. You can see the very high amplitude of frequencies with a bandwidth from .015 to .03 hertz. The high peaks to the far left of the chart indicate ULF emissions in the .001 to .003 hz range.

The chart below is of the same time span only in Log format for those who are accustomed to viewing in this mode.

fft21209.gif (18824 bytes)
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This last graph is a magnetometer chart of this time period courtesy of the Swedish Institute of Space Physics. The graph indicates low geophysical activity until around 22:00 UTC. Apparently the precursor activity in the above charts was not related to any magnetic anomalies. In some instances during heavy magnetic storms the precursor signals are masked by voltages generated by solar flares etc., in this case however, the earth's magnetic field was very quiet.  

1209eq.gif (8741 bytes)
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