 So just to remind you that this is before and for the information of those who have not, my name is Jürgen Sturff-Napsson, I come from Reykjavik University and I've been monitoring a lot of our seven structures in Iceland and a two large part for electric motion. And so this is a case from one of our buildings located in CERFOS and we have an observational and seismometric data and structural analysis that's been done on the buildings and a kind of controlling the vulnerability curves are available for the buildings in this area based on damaged estimation after the events. So there is a considerable amount of data available. This study really involves around three big earthquakes that occurred two in the year 2000 and which are not that close to the building that is the center of the topic but then in 2008 we had a third earthquake which is actually only about five to ten kilometers away that was actually a complicated fracture and there were two faults that went off simultaneously with the closest epicenter just roughly five kilometers away from the town and these pictures shows the aftershock for the few months after the main event and this is the building, it's a three story building with a basement and we have instrumentation in the building on the top floor, the red sensors in each corner and in the center and then in the basement we have our reaction. So the building is built in the 1940s. It's instrumented in 1999 just prior to the first earthquake series that we had there. So what we actually noticed was that there was very strong dissimilarities in the structural response characteristics for these two events in 2000 at a distance of 15 kilometers and in 2008 with a central distance of about five to eight kilometers and we had of course much larger background accelerations in the 2008 event, only 13% of G in 2000 about 54% in 2008 and we had a normal response in 2000 with a magnification factor from the base to top of three but in 2008 we had a much lower magnification, 144 and so we also noticed that the frequencies observed in the recorded signals had all shifted down and we see this also in, when we compare the horizontal vertical spectral ratios that the peak used to be close to eight parts here which harmonizes with the natural frequency of the structure or goes down to two hertz. The natural frequency of the building is around seven hertz, so it's in this range. For a low-rise building like this it's, you don't get really very clear peaks. You can see here for instance this would be the natural frequency of the structure close to eight hertz. So we suspect we have a natural rock soil profile based on a borehole or a section that was made not that far away from the building within the surface area and there we see that the building would be on top of this and then underneath there is lava layers, compound lava, sporeal lava and then a sediment layer and of the couple of meters to three meters thick which was accumulated during geysage, during interglacial periods where we had sea level where we have a hundred meters above sea level today. So the sea was flowing over this area but we now have a lot of building in the agricultural area and then when the ice age was finished 10,000 years ago there was a lot of volcanic activity in Iceland and then the lava flow over the salt sediments. So we have a different structure close by, this tower we have sort of verified that if we make a simple model of the foundation structure we get a very good correlation with the natural frequencies of the tower observed in the top of the tower but if we don't include the foundation levels then we are never able to simulate what we actually monitor because the structure itself is much different, it's close to 10 hertz. So the prior design assumptions for buildings in the area was that we had the stiff soil or a rock base and based on that you picked out the loading from Eurocode, we are a response factor or whatever and this was in a way ratified by the other bit went in 2000 which didn't show anything other than that this would be an okay way to go, a good assumption that you have stiff soil there but then in 2008 this changed so we have strong soft soil effects and the effects of this soft layer is basically that it increases the PGA levels of the surface and therefore it induces increased action on building contents and there was a lot of damage on building contents in this event but for short period structures it acts as a seismic isolator so if we have a structure with natural frequency of 4-5 hertz it will actually the safety of the structure itself will increase so we are talking about 4-5 or maybe up to 6 story buildings and we see this partly from the modification factor that I mentioned before but if you have longer period structures then it will actually act as an excited because the soft layer will basically be so the long period structure will be sort of a secondary structure based on this primary structure that is vibrate at a frequency around 2 hertz and we get decreased safety so this is basically summary of what I've already told you regarding the information so there is not much yet but actually that we have data available we have done some analysis but those further analysis include some information I'm taking maybe changing the content of the citation which is we believe it depends on the magnitude of the action and this may have consequences for structural design oops that was too close so what my idea was and what we were discussing yesterday was to do a sort of a simplified model for building and foundation where the foundation there would have probabilistic parameters we could do this for a series of buildings basically put in with a simplified simplifying assumptions just vary the period of the top structure and we could have two foundation cases active and inactive soft layer or we could even have one case for the large variability in stiffness and we could maybe use great limits to determine the safe or unsafe behaviors so that would be the and for unsafe we would have decision like to improve the knowledge through further analysis such as portal section analysis or we could demand additional foundation work so the buildings would be built on plates for instance instead of on top of the lava and for even not to build so but this is not the final population I think but sort of the idea that this is ongoing very interesting, are there any questions? I would like to add value to your work is probably to use an accelerometer on the soil because you are doing the structural interaction one thing would be of course to implement no but just not need to implement just to do the H over V ratio method for the soil and to see the frequency of resonance right but that's basically what we have already in SS because we have the we have the instrumentation in the building this is in the building but you can do it for the building I mean we have the accelerometer it's in the elevator core at the bottom layer of the building so it's just above the surface layer basically so this is basically measuring the surface acceleration but not the I don't know but I think it's influenced by the structure you need to put it next to it when you have just the soil there is not much interaction this is sort of the traditional way this is the traditional way for the structure I mean this is the input into the structure and there is not much difference between this and an accelerometer out in the free field you don't especially for a stiff structure like this you don't get that much interaction I'm not discussing the interaction just for example I'm discussing more the resonance so probably if you get H over V you would know the peak when the soil is going to get into frequency if you compare it to the peak of so this point just to check if there is a positive this is a spectral ratio that we have evaluated from the basement measurements so I think that this should be done systematically on all the data I agree with you, definitely and that would give us also an idea about the variability with time because when the earthquake hits it sort of puts everything out of shape and it's open up to the layer but as time passes the soft layer is stiffened up again and we are in a position to track that we have data but we haven't really done systematic analysis of it so the idea is to use or not the monitoring of the soil well the monitoring for this study I think the data would be mostly used for validating the initial modeling in essence and perhaps evaluate the probabilistic characteristics of the parameters for the foundation to put some value on variance and things like that yes on the data that we have we're always concerned perhaps likely spectral for some little vertical spectrogression so what do you say? I think this is a notice in case we have been we have been trying to I would recommend to work forward with this variability case or host a shorter distribution getting clear decisions in our own this is for maybe not very it's too many decisions I think everything is there but just need some structure maybe a few weeks efforts and of course I'm going to finish my fact sheet and try to do a full jump and then fill it out maybe get some more structure but the SDSM I would put that here and probably it might be very useful to me to get students to listen to me and work on this if he has participated in the training anybody who works like a SDSM to