Dr.Eng.Constantin Ionescu - Technical Aspects of DACEA EWS
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- Published on Friday, 25 January 2013 14:47
Ladies and gentlemen,
We thank you for taking part in launching our project. The implementation of such a project would not have been possible if it had not been for research and for such people as Dr. Solakov and Dr. Marmureanu and Dr. Bonjer who were presented this morning. Building an EWS [early warning system] is only possible if you have a very good infrastructure: it means having a good seismic network that can cover a very good distribution of the territory. And our institute has that, just like the institute in Sofia.
I will present the technical matters of the project. The main objective of the project is to have an early alert system of the authorities using the two national networks in Romania and Bulgaria. Also the purpose is to improve the procedures that we use nationally in Romania and Bulgaria for both prevention and reaction of the authorities in case of a major earthquake.
How was this alert system possible? Well..., this was possible because Vrancea ? , for example, is distributed on a very small area of 30 by 70 meters with depths between 60 and 150 km. The largest earthquakes in last century are those in 1940, 1977, 1986 and 1990, but the earthquake from which we've learned a lot is the one in 1977. Everybody remembers the damage caused in Bucharest, the deaths, and other losses caused not just in Bucharest but in other counties in Romania as well as in Bulgaria.
This places Bucharest among the most dangerous cities in Europe. As you can see over 1500 people died in 1977; 32 tall buildings were affected. And I'm talking about buildings that had been built both between the two World Wars, when there were no building standards, but also new buildings.
Mr. Bonjer mentioned the philosophy behind an alert system. Well, this is quite simple, since it is based on the analysis of the two seismic waves, the primary and secondary waves. As you know, the one that is the most damaging is the secondary wave presented on your right-hand side of the screen with an "S". On the map, you have the travel times of the secondary wave at the depth of 130 km as it can start from Vrancea. As you can see, in Giurgiu the time lag is 40 seconds, in Zimnicea 50 seconds. The farther we get from the epicenter, the longer the time. Again the same slide that Mr. Bonjer presented.
This research formed the basis for the creation of this earthquake alert system. In order to prove that this system is functioning we took two earthquakes as examples: one 130 km deep, where we have a warning time of 29 seconds and another one which is 70-80 km deep, where the warning time for Bucharest is 35 seconds and this is enough to have a good management in case of an earthquake. Here are the responsibilities for what to do in case of an earthquake. You use a seismic station, a network (there is an analysis), the alert occurs and after the alert the authorities have the responsibility to intervene. As you can see, it is quite important for any government to try to prevent any earthquake bad efects. And this involves educating the population, improving the construction standards and then intervening and alerting the people and peer using the measurement and communication tools.
Our project targets the two areas in the North and the South of the Danube area, covering seven counties in Romania and eight municipalities or counties in Bulgaria. As you can see, all pieces of information used for this system come from the Romanian seismic network, but also from Bulgaria. In order to create this system, we focused on four seismic areas: Vrancea area, which affects most of the Romanian territory plus Bulgaria, and the seismic areas in Northern Bulgaria (Shabla, Dulovo) and another region very close to the Romanian border. The purpose of this project is to improve the monitoring system of the Romanian and Bulgarian seismic networks with new seismic stations so that you can trace and asses within seconds how significant, how major that earthquake is.
On this map you can see with red dots the existing seismic stations and the yellow dots refer to the seismic stations that will be installed so that they increase the trust and detection or tracing period, the strength (magnitude) of the possible major events that can occur in Bulgaria and Romania. As I said the warning systems are used before the second wave gets to the location where you are currently present, so this means an improvement of the reaction time: in case of an earthquake you can protect facilities of national interest, chemical or gas facilities, nuclear installations. This information is sent via secure systems that connect the earthquake assessment systems and the users.
Here you can see a chart showing the travel time of the secondary wave between the epicenter and various localities in Romania and Bulgaria for an earthquake occuring at the depth of 130 km in Vrancea. The same thing for an earthquake in Shabla, at 10 km depth where the travel time is very short (for Shabla just four seconds and the farther we go from the epicenter the longer the time).
What tools we use to get the message? Well, the message is sent or shall be sent only to the two centers in Bucharest and Sofia. These messages are sent on cell phones through Tetra-secure systems that the governments use, on dedicated systems developed in secure networks. If an earthquake occurs, we can generate various maps as the ones on the slide that let us assess the intensity in various regions. For example, for an earthquake over 7 degrees' magnitude you can have intensities of 5, 6, 7, 8, depending on how strong that earthquake was. Based on the records in the seismic stations that are installed in the two regions, we can assess how bad the effects of the earthquakes were and what the damages were, of course.
Maybe you might say that once the earthquake has happened, there's no earthquake management anymore. Well, after the earthquake, we as institutes, produce the so-called maps and bulletins to describe the earthquakes parameters, the acceleration rates, the damage assessment and various maps, also based on questionnaires that the citizens answered to. This is a chart describing the way in which data is sent and produced.
Once the secondary wave has hit one location, 90 seconds afterwards the institutes sent the first seismic bulletin with respect to the earthquake parameters. The parameter means how big the earthquake was, the scale, where it happened and its magnitude, of course. Then follows the distribution of the accelerations and the intensities, the so-called shake map. All these maps and information go to the inspectorate for emergency situations, to the national committees for emergency situations or those working at the county level. After this shake map is produced, the damages are estimated in various regions. All of these messages flow constantly between the data centers and authorities.
Here is information about the acceleration value in various parts of the seismic stations. We've got the shake map describing the intensity distribution to the left hand side and the acceleration distribution in the right-hand side. Here is the shake map for the earthquake that took place on April the 25th 2009 that was of 5.7 degrees. For Bucharest, we simulated for the same earthquake an intensity distribution shake map, by segmenting Bucharest into regions. Here is a distribution of the acceleration and ground velocity at seismic stations and under the current we are working on the damage map for cases of earthquake over 5. So we planned to asses all these damages for earthquakes of over 5. The same thing here can be seen here again in a Google map (GIS) format. Now once the earthquake is over, what is important to the institute is to get the reaction of the citizens in order to know how the citizens felt it. We've provided a questionnaire on our website where citizens can fill in some answers based on which we can asses the local intensity in various localities where the respective person was.
The usage chain of such information will benefit the institutes, local authorities, the risk providing facilities and the public. The institutes and authorities are connected through various systems. As I mentioned we have government communications systems like Internet, mobile phones, fax, email, radio and TV satellite band FM, RDS systems. These communication channels will be provided in case of an earthquake after the project is completed. These communication channels can also be used after the project is over, in a real-case earthquake.
As you can see this type of information distribution system can be used for both floods and tsunamis, earthquakes, fires.
That's everything I had to say, very brief, actually quite technical.
Maybe not everybody knows about the equipments behind me. There are two equipments for gas blocking. This one on your right-hand side can be installed wherever anybody has gas supply. This is installed on a building and it uses a valve that taps off the gas. It can be set at various accelerations depending on the building standard in that respective area. The other equipment, the taller one, on your left-hand side, gets information from the data-centers, such as the institute. It reacts in the range of 25 seconds for Bucharest, before the secondary wave gets from Vrancea to Bucharest. These are very useful things for installations that can cause damage in case of an earthquake, as I said, chemical or gas installations, nuclear power plants and other type of nuclear systems. They can also be used by the population as well.
Thank you.
