Abnormal Animal Behavior Prior to the Vrancea (Romania) Major Subcrustal Earthquakes

The goal of this paper is to present some observations about the abnormal animal behavior prior to and during some Romanian subcrustal earthquakes. The major Vrancea earthquakes of 4 March 1977 (M_W = 7.4, Imax = IX–X MSK), 30 August 1986 (M_W = 7.1, I₀ = VIII–IX MSK) and 30 May 1990 (M_W = 6.9, I₀ = VIII MSK), were preceded by extensive occurrences of anomalous animal behavior. These data were collected immediately after the earthquakes from the affected areas. Some species of animals became excited, nervous and panicked before and during the earthquakes, such as: dogs (barking, howling and running in panic), cats, birds (hens, geese, turkey hens, ducks, pigeons, parrots), cattle, pigs, mice and rats (came into the houses and have lost their fear), horses, fishes, snakes etc. These strange manifestations of the animals were observed on the entire territory of the country, especially in the extra-Carpathian area. This unusual behavior was noticed within a few seconds to days before the seismic events, but for the most of cases the time of occurrence was within two hours prior to the quakes. We hope that one day the abnormal animal behavior will be documented enough in order to be used as a reliable seismic precursor for the intermediate depth earthquakes.