a division of Zoltech Corporation

VolksMeter II



Milpitas, California 5.6M eq
31-Oct-07 03:04:54 UTC
1 Quake - 3 VolksMeters

Here we have a single earthquake as seen by three different VolksMeters at different locations around the U.S.  As it happens, each VolksMeter was about an order of magnitude closer to the earthquake location than the one shown before it; with great circle distances of 4002Km, 465Km and 42Km respectively.  The time delays and the waveform shapes show the effects of these varying distances.  Note that the absolute magnitudes of the three helicord records are not strictly comparable since the vertical scales are set differently at each instrument.
Milpitas 5.6M eq from Havertown, PA USA
4002Km - Havertown, PA (courtesy of Michael Kimzey).  First shock arrived about 03:23 UTC, 19 minutes after the USGS reported quake time.
Milpitas, CA 5.6M eq from Van Nuys, CA USA
465Km - Van Nuys, CA ( RLL Instruments).  First shock arrived about 03:05:57 UTC, 1 minute after the USGS reported quake time.
Milpitas, CA 5.6M eq from Redwood City, CA USA
42Km - Redwood City, CA (courtesy of Larry Cochrane).  First shock arrived about 03:05 UTC, 6 seconds after the USGS reported quake time.

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