January 11, 1996 a single seismograph of the Geological Survey of Canada buried in a quiet wooded area on central Vancouver Island started to record an unusual strong seismic signal
– slowly, but perpetually increasing in amplitude over time it was
recorded only at this station – nearby station (located within a radius
of 20km) didn´t show any movements – this was no ordinary 6.8 magnitude
earthquake as could occur along the Cascadia Subduction Zone.
Fig.1.
Seismogram showing a segment of the unusual seismic signal, from
CASSIDY & WHITFORD 1996.
After one-half hour there was a sudden increase in intensity of the signal. The geologists at the Pacific Geoscience Centre in Sidney,
125 km distant of the seismograph position and monitoring the unusual
signal, decided to call the police and a nearby a public school to
check the situation.
Meanwhile the signal amplitude continued
to increase – and an ever increasing number of puzzled technicians and
scientist gathered around the monitoring equipment at the Geoscience
Centre. At 4:28 PM – 43 minutes after the unusual recording was first
noted – the signal suddenly stopped.
Later it was confirmed that it was
exactly at 4:28 PM that the police officers and the school staff
arrived at the seismograph site, where they found a young couple,
trembling in passion and the source of the recorded Love Waves and supposed man-made quake…
Bibliography:
CASSIDY, J.F. & WHITFORD, A. (1996): Unusual “Love Waves” Recorded Above the Cascadia Subduction Zone. Seismological Research Letters. Vol. 67(6): 49-51
