Romania is an earthquake prone area and it is of crucial importance to obtain quantitative information needed for seismic risk mitigation and related public policies and seismic safety measures. The most damaging earthquakes in Romania are concentrated in the Vrancea region, located at the sharp bend of the Eastern Carpathians Arch, in a well confined focal volume at intermediate depths between 60 km and 200km. Vrancea earthquakes have been documented for at least a millennium (since 985 a.c.) and represent very peculiar characteristics. They are a permanent threat for large urban areas in Romanian and other nearly areas of Europe. Bucharest is among the megacities most affected by the resulting destructive earthquakes.

The 1977 event had a catastrophic effect; 35 tall buildings collapsed and 1500 people were killed, the majority of them in Bucharest. A Earthquakes Early Warning System (EEWS) based on the travel time differences between the primary P-wave and the destructive S-wave allows a warning time of about 25 s. Peculiarities of the Romanian intermediate depth events, such as the stationary epicenters and the stability of radiation patterns, and a line-of-sight connection between the epicentral area and the capital allow the design of a simple and robust EEWS. Simplicity and robustness of the system are sought in order to reduce the risk of false alarms, which is crucial for making the system cost-beneficial.

The real-time detection of the dangerous seismic waves from Vrancea area is used for strong earthquakes. EEWS uses the time interval (that is about 25-28 seconds) between the moment when an earthquake is detected at the surface in the epicentre area (Vrancea) and the moment of arrival in the sites being warned. This time interval depends upon the depth and propagation conditions of the earthquake.

The EEWS installed in Vrancea area has four important modules:
- local seismic network for detection,
- 2 acquisition centres and computing facilities,
- redundant communication network,
- distribution to users.

The detection of the P waves at the epicenter is the first step in the early warning process. Three 3-component strong-motion accelerometers perform the detection in two different locations situated about 8 km apart. The first site is situated in Vrancioaia (VRI - 45.8656N, 26.7276E, 476 altitude). In the second location, Plostina (PLOR - 45.8512N, 26.6499E, 657 altitude, Vrancea area), are installed two accelerometers, one in a 50 m borehole and another in a vault.

In a bilateral programme between NIEP and GEOK (CRC 461 project) an EWS was implemented in Romanian for Vrancea earthquakes starting from 2001.
Using the first second of the recording, it is possible to have a preliminary estimation of the magnitude of the earthquake. A scale of eight levels is associated to the acceleration values detected from P waves. A seismic early warning alarm is triggered having the following details: time, peak acceleration value and level of triggering. An interactive analyzing module can modify the parameters of the alarm if, in the next seconds, the acceleration of the seismic waves increases.
EEWS works in the following steps: detection of the P waves, first arrivals analysis (fast Fourier analysis and acceleration detection coincidence on more than one accelerometer), alarm generation, sending of the alarm to the users (including also SMS and email). The communication is one of the most important parts of the EEWS. Redundant radio links ensure that communication between the Vrancioaia and Plostina sites and between Vrancioaia and the Romanian Data Center in Bucharest is maintained.

The main outcome of the project for this test site will be the testing and production of real-time shake maps, real-time damage estimates and the improvement of the early warning system.