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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS008 Poster presentation 2005
Possible association between some geomagnetic anomalies and Vrancea
(Romania) significant earthquakes occurred in the years 2004-2007
Dr. Moldovan Iren-Adelina
Bioseismic and magnetoteluric studies National Institute for Earth Physics IASPEI
Dumitru Enescu, Adrian-Septimiu Moldovan
The association between geoelectromagnetic anomalies and Vrancea earthquakes of moment
magnitudes 3.7 ≤ MW ≤ 5 was first proved by studying the magnetic and seismic data in the period
1997 - 2004. This finding was extended in 2004 to a broader magnitude range 3.7 ≤ MW ≤ 6.3. While
Vrancea earthquakes had never exceeded Mw=5 for nearly seven years, they did so in October 2004,
culminating with a seism of Mw = 6.3 on October 27, 2004. The hypocentral coordinates of the Vrancea
earthquake of October 27, 2004, are: 45.8 N, 26.7 E and h=100 km. Its macroseismic intensity was
Io=VII as a maximum (on the Mercalli scale) and I = VI in Bucharest. Further data with respect to
Vrancea seismic activity in the period 2004-2007 were taken from the seismic bulletins of the National
Institute for Earth Physics. The working data are represented by geomagnetic data as recorded at
Muntele Rosu The study proves that observable precursory anomalies in the geomagnetic impedance
have preceded all Vrancea earthquakes of moment magnitudes Mw≥ 4.0 occurred in 2004-2007 years.
This study confirmes the main result obtained in the first period, namely that the great majority of
Vrancea earthquakes of magnitudes higher than 4 are associated with precursory anomalies in the
geomagnetic impedance. It also seems that neither the precursor time nor the amplitude of the
precursory magnetic anomaly can be linked reliably with the magnitude of the anticipated earthquake.
Keywords: geomagnetic anomaly, earthquake, moment magnitude