Stress Forecasting in Vrancea (Romania): From Anomalies in Geophysics to the Mainstream
I.A. Moldovan1, A. Apostol2, C. Ionescu1, A.O. Placinta2, A.P. Constantin.2
1 National Institute for Earth Physics, Magurele, Romania, [email protected] 2 Center for Bioseismology, New York, [email protected]
The Vrancea seismically active region of Romania, situated far from active plate boundaries, can be characterized by small–large intermediate-depth earthquakes and small–moderate normal depth ones. A bio-location methodology has been performed trying to map crustal faults in and around Vrancea. Bio-location measurements measured across tectonic faults and geomagnetic continuous recordings have been used in the last decade in order to correlate the data to the local and regional earthquake activity. Certain correlations had been claimed, but they have been rejected by mainstream geophysics, due to an after-the-fact subjective evaluation. As a result, a real-time evaluation and stress forecasting has been proposed and implemented during the years 2009–2012.
A stress forecasting of a large earthquake for a window of time October 22–26, 2011, was issued to the National Institute for Earth Physics (INFP), on October 21 at 10:00 AM. A large earthquake magnitude 7.2 was recorded in Van, Eastern Turkey, on October 23. Another stress forecasting was issued on January 10, 2012, at 10:00 AM, for a moderate intermediate-depth earthquake in Vrancea, in a window of time of six days. A magnitude 4.3 earthquake was recorded ten hours later. This time the bio-location anomaly started in the same day with a geomagnetic anomaly.
However, our data suggest such anomalies can be related to the resistivity anisotropy and magnetotelluric wave splitting (MWS) around crustal faults nearby and not to possible phenomena at the focal region, as previously reported. On the other hand, the resistivity anisotropy anomalies recorded around tectonic faults are possible related to stress variations in magnitude and direction observed before, during, and after moderate–large local and regional earthquakes. Finally, a valid earthquake prediction is not possible, but stress forecasting is able to offer some data before local and regional moderate and large earthquakes.