Vrancea earthquakes. Courses for specific actions to mitigate seismic risk

Earthquakes in the Carpathian-Pannonian region are confined to the crust, except the Vrancea zone, where earthquakes with focal depth down to 200 Km occur. For example, the ruptured area migrated from 150 km to 180 km (November 10,1940, Mw = 7.7) from 90 km to 110 km (March 4, 1977, Mw 7.4), from 130 km to 150 km (August 30, 1986, Mw = 7.1) and from 70 km to 90 km (May 30, 1990, Mw = 6.9) depth. The depth interval between 110 km and 130 km remains not ruptured since 1802, October 26, when it was the strongest earthquake occurred in this part of Central Europe. The magnitude is assumed to be Mw = 7.9 - 8.0 and this depth interval is a natural candidate for the next strong Vrancea event. While no country in the world is entirely safe, the lack of capacity to limit the impact of seismic hazards remains a major burden for all countries and while the world has witnessed an exponential increase in human and material losses due to natural disasters given by earthquakes, there is a need to reverse trends in seismic risk mitigation to future events. Main courses for specific actions to mitigate the seismic risk given by strong deep Vrancea earthquakes should be considered as key for development actions: - Early warning system for industrial facilities. Early warning is more than a technological instrument to detect, monitor and submit warnings. It should become part of a management information system for decision-making in the context of national institutional frameworks for disaster management and part of national and local strategies and programmers for risk mitigation; - Prediction program of Vrancea strong earthquakes of short and long term; - Hazard seismic map of Romania. The wrong assessment of the seismic hazard can lead to dramatic situations as those from Bucharest or Kobe. Before the 1977 Vrancea earthquake, the city of Bucharest was designed to intensity I = VII (MMI) and the real intensity was I = IX1/2-X (MMI); - Seismic microzonation of large populated cities. There are zones in Bucharest which have fundamental periods of the soil and geological structures very different and during August 30, 1986 Vrancea earthquake the variations of the recorded peak accelerations were from simple to triple ones; - Shake map. This shake map now under completion will allow us rapidly portray, in real time, the extent of shaking during of earthquake in a simplified form suitable for immediate post-earthquake decision-making; - Seismic tomography of dams for avoiding catastrophes. There are applications of seismic tomography and in general of seismic imaging like methods of investigation for mitigation of earthquake effects. (authors)