WEBVTT Kind: captions Language: en 00:00:00.940 --> 00:00:03.080 [background conversations] 00:00:03.080 --> 00:00:05.260 Good morning. Hello, everyone. 00:00:05.260 --> 00:00:06.620 Thank you for coming on this Friday morning, 00:00:06.620 --> 00:00:10.640 and we’re very lucky to have Daniela visiting from Rome. 00:00:10.640 --> 00:00:12.190 I don’t have any other announcements for you. 00:00:12.190 --> 00:00:17.450 There’s no seminar next week, so you can all relax and catch your breath. 00:00:17.450 --> 00:00:19.680 David will introduce our speaker. 00:00:20.980 --> 00:00:24.860 - Well, I realize this is the Friday before AGU, 00:00:24.860 --> 00:00:29.399 and there have been other seminars this week, so those of you who actually 00:00:29.400 --> 00:00:36.800 made the trek over, I think you’ll enjoy a very, very interesting talk. 00:00:37.400 --> 00:00:41.080 Daniela had been invited over to the University of Nevada-Reno 00:00:41.080 --> 00:00:44.700 to give what they call the Slemmons Lecture. 00:00:44.700 --> 00:00:50.371 And I sort of twisted her arm a little bit, and I said, well, why don’t you come 00:00:50.371 --> 00:00:54.960 to the Bay Area and also give a talk down in Menlo? So she said, great. 00:00:54.960 --> 00:01:02.180 And Daniela is an earthquake geologist, paleoseismologist – so that’s 00:01:02.190 --> 00:01:06.689 really something big in her favor. [laughter] 00:01:06.689 --> 00:01:09.780 Currently, she is the director of the 00:01:09.780 --> 00:01:13.909 Earth Science department at the INGV in Rome. 00:01:13.909 --> 00:01:17.939 And the Earth Science department includes not only earthquake geology, 00:01:17.940 --> 00:01:24.780 but the national seismologic network and the national geodetic network. 00:01:27.689 --> 00:01:32.380 Daniela has worked in paleoseismology around the world, 00:01:32.380 --> 00:01:38.909 and particularly in Europe. Not only Italy, the Gulf of Corinth, 00:01:38.909 --> 00:01:44.520 other parts of Greece, Iran, Libya, and even in California. 00:01:44.520 --> 00:01:51.900 And I first met Daniela in 1988. So we go back to the early Precambrian. 00:01:51.900 --> 00:01:57.700 And our first project together was in 1989, where we did trenching 00:01:57.700 --> 00:02:03.940 of the 1980 Irpinia surface rupture in southern Italy. 00:02:03.940 --> 00:02:09.910 Today, Daniela’s going to talk about the 2016 earthquake 00:02:09.910 --> 00:02:15.140 sequence in the central Apennines. And actually talk a little bit about 00:02:15.140 --> 00:02:20.070 some of the prior events leading up to this and then say something about 00:02:20.070 --> 00:02:24.760 what may happen down the road. So, Daniela, you’re on. Thank you. 00:02:24.760 --> 00:02:28.480 - Okay, thank you, David. Thank you, everyone. 00:02:30.200 --> 00:02:36.540 Okay, David already introduced the topic of this presentation. 00:02:36.540 --> 00:02:44.360 And I will try to go through a small introduction on what happened in Italy. 00:02:44.370 --> 00:02:52.730 You know that Italy is a seismic country. And here you have two figures that 00:02:52.730 --> 00:03:02.400 show you the last 10 years’ seismicity and the seismicity of the last 1,000 years. 00:03:02.400 --> 00:03:04.970 As you know, we have a very good catalog 00:03:04.970 --> 00:03:11.320 of historical seismicity, and this shows us that the main – the largest event – 00:03:11.320 --> 00:03:17.760 historical event occurred mainly along the axis of the Apennines. 00:03:18.900 --> 00:03:25.180 You see the arrow? Yes. That ran all along the peninsula and 00:03:25.180 --> 00:03:29.950 goes down to Calabria and Siciliy. Then we have another little spot 00:03:29.950 --> 00:03:39.430 of magnitude close to 7 earthquake in this – in this area. 00:03:39.430 --> 00:03:46.060 So the rest of Italy – so most of the instrumental seismicity 00:03:46.060 --> 00:03:53.940 occur along the Apennines at crustal depth that is between – let’s say – 00:03:53.940 --> 00:03:55.460 you have three main colors, mainly. 00:03:55.460 --> 00:04:00.790 So the yellow is above 10 kilometers. The green is up to 30. 00:04:00.790 --> 00:04:07.900 And the blue ones is the – what is the remnant of our subduction slab. 00:04:07.900 --> 00:04:13.930 So we have earthquake up to, I think, 400 kilometers deep here. 00:04:13.930 --> 00:04:21.060 So the earthquake sequence of – the 2016 earthquake sequence occurred 00:04:21.060 --> 00:04:27.540 in the central part of the Apennines in an area where historical seismicity 00:04:27.540 --> 00:04:34.061 was clear, telling us that what occurred in the past may occur in the future. 00:04:34.061 --> 00:04:41.380 And we had a magnitude 6 and 7 during the past 1,000 years in this area. 00:04:41.380 --> 00:04:50.320 But why we have – so something I didn’t say is that this area is 00:04:50.320 --> 00:05:00.139 characterized by normal faulting events. So the 2016 sequence was one of this. 00:05:00.139 --> 00:05:03.870 But we are in a – so we have normal faulting earthquakes, 00:05:03.870 --> 00:05:10.000 but we are at the boundary between two plates that are converging. 00:05:10.000 --> 00:05:14.790 What happened is that we have a remnant of a – 00:05:14.790 --> 00:05:22.650 of a slab here that you see in red that is the remnant of the 00:05:22.650 --> 00:05:30.520 subduction that was producing the build-up of the Apennines. 00:05:30.520 --> 00:05:40.950 The geometry is so complicated now that we – in the – in the central part of Italy, 00:05:40.950 --> 00:05:46.100 we are in – I don’t find the arrow. I have lost the arrow. I am sorry. 00:05:46.100 --> 00:05:48.680 - [audience responses] - It’s on the screen. 00:05:48.680 --> 00:05:51.430 Okay. I don’t see it here. 00:05:51.430 --> 00:05:56.940 And so, in the central part of the Apennines, we are in a situation like this. 00:05:56.940 --> 00:06:03.720 We may have that the slab detached, so we have a rebound of it and a retreat, 00:06:03.720 --> 00:06:07.380 and so extension on the Apennines. 00:06:07.380 --> 00:06:15.530 Or we can just have a rollback of the slab anyway with the normal fault on 00:06:15.530 --> 00:06:22.020 this side of the Apennine and still some compression on the east. 00:06:22.020 --> 00:06:28.680 So we are in a normal faulting environment, and this is very clearly 00:06:28.680 --> 00:06:35.600 seen from the GPS data. Here you have a GPS velocity map. 00:06:35.600 --> 00:06:41.920 And you can see that most of the arrows go to the east-northeast. 00:06:41.920 --> 00:06:50.140 But in this – oops – in this part, you have a divergence. 00:06:50.140 --> 00:06:56.920 The arrows – smaller, they go this way. And so this produce an extension in – 00:06:56.920 --> 00:07:05.300 across the Apennines and exactly where we had our last earthquake. 00:07:05.300 --> 00:07:10.000 This is to show that, where we have the highest velocities, 00:07:10.010 --> 00:07:14.190 we have the main normal faults. So there is a zone of normal faults, but 00:07:14.190 --> 00:07:20.690 those that ruptured in recent times are – correspond to this high-velocity area. 00:07:20.690 --> 00:07:26.710 So what happened was that, on August 24th, 2016, the sequence 00:07:26.710 --> 00:07:32.260 started with a magnitude 6 earthquake. Then we had some other – 00:07:32.260 --> 00:07:40.880 two main shocks in October, so two months later –a 5.9 and a 6.5. 00:07:40.880 --> 00:07:47.600 And when we thought, okay, we can relax in January, we had, again, 00:07:47.610 --> 00:07:56.930 a backup of seismicity with four over-5 – over-magnitude 00:07:56.930 --> 00:08:02.260 earthquakes in the southern part of the sequence. 00:08:02.260 --> 00:08:11.460 We can see in this map how the sequence evolved. And aftershocks, with time, 00:08:11.460 --> 00:08:23.520 took an area of about 80 kilometers in a northwest-southeast direction. 00:08:23.520 --> 00:08:34.700 And so this is the last series of event – the blue ones, with four magnitude 5 00:08:34.710 --> 00:08:42.540 and over in one – in two hours, actually. So this was quite scary. 00:08:44.600 --> 00:08:49.260 The first event – so the October 24th – 00:08:49.260 --> 00:09:00.220 was the most destructive one with – and caused about 300 victims. 00:09:01.920 --> 00:09:05.940 In total, we have more than 40,000 homeless. 00:09:05.940 --> 00:09:11.350 They are going – some of them are going back to homes, or they have 00:09:11.350 --> 00:09:18.570 some small – we call earthquake homes made of wood in the area 00:09:18.570 --> 00:09:21.890 where they were living. But they spent a lot of – 00:09:21.890 --> 00:09:25.830 they spent a – probably about a year far from 00:09:25.830 --> 00:09:29.820 where they were living or they were working. 00:09:29.820 --> 00:09:36.340 And then the lost – our estimated – the economic losses are estimated 00:09:36.350 --> 00:09:45.810 at more than 10 billion euro. But many of – for a large part, 00:09:45.810 --> 00:09:51.300 they cannot even estimate it because they involved historical 00:09:51.300 --> 00:10:01.380 and artistic buildings or pieces of art that remained 00:10:01.380 --> 00:10:07.780 under the ruins of building, churches, and whatever. 00:10:07.780 --> 00:10:16.920 So this was – this is a representation of the seismicity before – 00:10:16.920 --> 00:10:21.220 one year before the first earthquake. 00:10:22.280 --> 00:10:27.700 Maybe I didn’t go clear – yeah, I explain you that there are three events. 00:10:27.700 --> 00:10:33.820 Anyway, so we – here you can see the number of events. 00:10:33.820 --> 00:10:38.380 And so, after a year of complete silence, 00:10:38.380 --> 00:10:44.430 we had this magnitude 6 shock that started the sequence. 00:10:44.430 --> 00:10:54.860 And then we had a period – so the dots are the moment release, 00:10:54.860 --> 00:10:59.570 and the histograms are the number of events. 00:10:59.570 --> 00:11:06.150 So we thought the seismicity was – so the energy release was going down. 00:11:06.150 --> 00:11:14.680 So it was quite low when the sequence started again with the 00:11:14.680 --> 00:11:26.800 two October events at 5.9 and a 6.5. Then we had a period of quite decrease 00:11:26.800 --> 00:11:31.570 of both moment and the number of events, but you can see that 00:11:31.570 --> 00:11:35.820 the moment is still quite – moment release is still quite high. And those 00:11:35.820 --> 00:11:44.400 are the January events. And today, we are still quite – at a quite high level. 00:11:44.410 --> 00:11:49.030 This is the space-time evolution. But what I want to show you is that – 00:11:49.030 --> 00:11:56.120 the same graph. This is just the number of event, but we are here. 00:11:56.700 --> 00:12:04.340 And you can see this – there is a kind of a increase of number of events and 00:12:04.350 --> 00:12:11.040 also of the moment release because, in the northern part of the sequence, 00:12:11.040 --> 00:12:20.019 in those days, starting of April 10, when we have a magnitude 4.7, 00:12:20.019 --> 00:12:30.360 we had about 2,000 small events that keeps going in this part. 00:12:30.360 --> 00:12:35.000 So I should tell you, we are kind of worried about this. 00:12:35.000 --> 00:12:46.420 Because we kept having small earthquakes all along this blue area 00:12:46.420 --> 00:12:59.170 that is the aftershock area. But now we have this concentration to the north. 00:13:01.620 --> 00:13:05.700 Okay, this is to show you the location of this shock. 00:13:05.700 --> 00:13:08.500 But I want to show you this. 00:13:08.500 --> 00:13:12.120 Why we are worried. Because, okay, this was 00:13:12.120 --> 00:13:20.339 the 2009 earthquake area. This was the 1997 earthquake area. 00:13:20.339 --> 00:13:25.960 We had a small earthquake in 1979. So this is – the yellow is the area 00:13:25.960 --> 00:13:37.209 that is filled by this 2016 sequence. So, in a way, we are filling a seismic gap. 00:13:37.209 --> 00:13:41.160 So someone said, oh, why – you had a seismic gap. 00:13:41.160 --> 00:13:44.260 You didn’t advise us – alerted us. 00:13:44.260 --> 00:13:49.079 But, of course, it doesn’t make any sense. 00:13:49.079 --> 00:13:55.089 It’s an area of low instrumental seismicity, and we have 00:13:55.089 --> 00:14:04.960 a recurrence time of earthquakes that is on the order of 500, 1,000 years. 00:14:04.960 --> 00:14:11.050 But now, what is going on – where is this – is that this part 00:14:11.050 --> 00:14:19.920 is starting to release energy again. So we are wondering if this is – 00:14:19.920 --> 00:14:25.260 this is an area of transition to something – to the north. 00:14:26.000 --> 00:14:29.310 We don’t know faults to the north. It’s an area that is 00:14:29.310 --> 00:14:37.430 full of terrigenous deposits. So it’s very tough to do geomorphology. 00:14:37.430 --> 00:14:42.310 So anyway, that’s what is going on those days. 00:14:42.310 --> 00:14:49.480 It’s a change with respect to what we had in the last year. 00:14:51.300 --> 00:14:58.080 This area was hit by historical earthquake, and the red ones 00:14:58.089 --> 00:15:05.209 are two earthquakes that occurred in 1703 that were close to 7. 00:15:05.209 --> 00:15:10.042 And then you can see there is plenty of these orange boxes 00:15:10.042 --> 00:15:13.019 that say between 6 and 6.4. 00:15:13.019 --> 00:15:17.800 That seems to be the common magnitude for the earthquakes in this area. 00:15:17.800 --> 00:15:25.460 But you can notice that all the historical epicenter are located in this area. 00:15:25.460 --> 00:15:31.240 A little bit to the – to the west with respect to the area that was 00:15:31.240 --> 00:15:36.180 hit by this earthquake. And we don’t know if this shift 00:15:36.180 --> 00:15:41.010 is related to the fact that the main cities were on this side, 00:15:41.010 --> 00:15:45.820 and here you are in the highest mountainous area. 00:15:45.820 --> 00:15:52.760 Anyway, the 1703 had some similarities with this earthquake because it tells – 00:15:52.760 --> 00:16:01.700 as well as the 1997. So those are multiple shock – main shock events. 00:16:01.700 --> 00:16:06.860 So probably this is something typical of this area. 00:16:06.860 --> 00:16:12.440 Because in 1703, within one month, we had two large shocks. 00:16:12.440 --> 00:16:21.440 And in 1997, we had three shocks within one month – two months. 00:16:21.450 --> 00:16:28.480 So this maybe tell us something. So here we had three shocks 00:16:28.480 --> 00:16:34.600 in two months. So we will talk about this later. 00:16:34.600 --> 00:16:42.410 So from the did-you-feel-it questionnaires, it’s clear that 00:16:42.410 --> 00:16:48.510 the magnitude 6.5 that is the largest event we had in Italy 00:16:48.510 --> 00:16:56.580 after the 1980 Irpinia earthquake that occurred far to the south, 00:16:56.580 --> 00:17:02.899 was felt in a very broad area. And we had reports even from Austria. 00:17:02.899 --> 00:17:09.980 So the ShakeMaps show that we had ground motion – important ground 00:17:09.980 --> 00:17:14.400 motion even though – even in the small – in the smaller events. 00:17:14.400 --> 00:17:23.470 So in the magnitude 5.9, we have places with ground motion 00:17:23.470 --> 00:17:29.580 that was close to 1 g. And the damage in the – 00:17:29.580 --> 00:17:35.140 what we had is not [inaudible] for this area. 00:17:35.140 --> 00:17:40.260 Because the area is in the – is located here, and you can see 00:17:40.260 --> 00:17:49.200 this purple and red show – this is for the intensity felt – 00:17:49.200 --> 00:17:55.090 recorded for the last 1,000 years. And you can see that this area is 00:17:55.090 --> 00:18:01.040 one of the areas that was repeatedly hit by earthquakes. 00:18:01.040 --> 00:18:06.460 And in fact, also in this case, the damage was terrible. 00:18:06.460 --> 00:18:12.169 So this is Norcia. This is the church of St. Benedict that is the saint 00:18:12.169 --> 00:18:19.280 that protects Europe. And it was – is doing – in very bad shape. 00:18:19.280 --> 00:18:25.220 But it’s even worse to see images like this from Amatrice. 00:18:25.220 --> 00:18:31.480 So this is a photo taken after the magnitude 6 earthquake. 00:18:32.860 --> 00:18:40.080 So there were some site effects and amplification, 00:18:40.080 --> 00:18:50.710 but the situation is really – is really bad, and you can see the type of building 00:18:50.710 --> 00:18:57.160 that were forming this medieval – this, yeah, village. 00:18:57.160 --> 00:19:01.380 This is another – I think it’s Arquata. 00:19:01.390 --> 00:19:07.150 You can see that there are only a few roofing still standing. 00:19:07.150 --> 00:19:13.640 So it was really shocking for all of us to see this amount of crumbles. 00:19:14.460 --> 00:19:22.280 But it was not only a problem of the buildings. 00:19:22.280 --> 00:19:27.151 Because here you have a typical – so this is a masonry building 00:19:27.151 --> 00:19:32.150 that was the typical type of building we had there. 00:19:32.150 --> 00:19:40.110 You should notice that the walls are built with cobbles from the river terraces. 00:19:40.110 --> 00:19:43.640 So something that is the worst thing you can do. 00:19:43.640 --> 00:19:51.620 But this area was built up around the 17- and 1800s, so just after the 00:19:51.620 --> 00:19:58.460 large 1703 earthquake. And they were poor people – mainly shepherds. 00:19:58.460 --> 00:20:02.650 So they did the easiest thing they could do. 00:20:02.650 --> 00:20:11.740 But you can see that also the [inaudible] concrete buildings suffered a lot. 00:20:13.340 --> 00:20:18.600 So this is a map that show you the distribution of damage. 00:20:20.460 --> 00:20:28.420 You can see here the scale. And I think it’s 20 kilometers – 00:20:28.420 --> 00:20:32.900 the scale down below. So this should give you an idea 00:20:32.900 --> 00:20:40.540 of the size of the area that was severely damaged. 00:20:41.820 --> 00:20:47.840 One thing that we should notice is that, in the southern part here, where we had 00:20:47.840 --> 00:20:54.870 the beginning of the sequence – so the magnitude 6 occurred here. 00:20:54.870 --> 00:21:00.730 There should be a star. You have black and dark purple dots. 00:21:00.730 --> 00:21:04.650 That means very high intensity. 00:21:04.650 --> 00:21:08.600 And you saw the destruction in Amatrice in the previous slides. 00:21:08.600 --> 00:21:15.880 While, if you go near Norcia – so this is the site of the 6.5, 00:21:15.880 --> 00:21:17.909 you get – you don’t get black here. 00:21:17.909 --> 00:21:30.530 You get some red and purple dots that should be – this is the European scale. 00:21:30.530 --> 00:21:34.250 Anyway, but the damage is quite different, 00:21:34.250 --> 00:21:43.150 although here you are very close to a 6.5, and here only to a 6.6 00:21:43.150 --> 00:21:50.140 What we think is that this is related to the type of buildings and to the 00:21:50.140 --> 00:21:58.200 retrofit that was done in Norcia for – during the centuries. 00:21:58.200 --> 00:22:03.280 In fact, you can see Norcia – apart from the church that is 00:22:03.280 --> 00:22:07.090 in bad shape, all the rest of the roofing is still on. 00:22:07.090 --> 00:22:13.419 So at least nobody was – there were no victims. 00:22:13.419 --> 00:22:17.539 So the victim were only in this part for the 00:22:17.539 --> 00:22:24.920 magnitude 6 earthquake where you have this rubble of stones. 00:22:24.920 --> 00:22:28.660 So what we think is that Norcia suffered – 00:22:28.660 --> 00:22:32.240 you see may earthquake above intensity 7. 00:22:32.240 --> 00:22:39.920 That is what we consider the threshold between damage and just small cracks. 00:22:40.740 --> 00:22:49.000 And Amatrice had some earthquakes in the 16- and 1700s, but then nothing. 00:22:49.000 --> 00:22:57.600 And all the earthquakes between 1800 and today were just felt from the 00:22:57.600 --> 00:23:05.200 distance, so they didn’t have any reason to remodel or retrofit their buildings. 00:23:05.210 --> 00:23:11.580 So this is – this is probably true for most of the Apennines. 00:23:11.580 --> 00:23:16.490 So the places that had an earthquake, they were remodeled, retrofitted, 00:23:16.490 --> 00:23:25.750 and rebuilt safely. But the places where we didn’t have damage from 00:23:25.750 --> 00:23:31.440 an earthquake just said, oh, we were lucky, and we will survive like this. 00:23:31.440 --> 00:23:38.320 And this is a typical example for something that occurred years ago. 00:23:38.320 --> 00:23:52.490 But we – the present-day law is – so make mandatory to build for – 00:23:52.490 --> 00:23:59.120 to build for anti-seismic with some rules, only for new buildings. 00:23:59.120 --> 00:24:03.440 So older buildings that are like this, from outside very nice, 00:24:03.440 --> 00:24:07.020 they can be really, really bad. 00:24:08.160 --> 00:24:12.020 So let’s go back to this – so I will concentrate mainly 00:24:12.030 --> 00:24:17.039 on the 6.5 earthquake. But anyway, this is to show 00:24:17.040 --> 00:24:24.640 GPS extension and that was – this is for the 6.5. 00:24:24.640 --> 00:24:31.419 And of course, we have evidence for extension and – only to the north. 00:24:31.419 --> 00:24:35.340 And in the central part, we have a few focal mechanism 00:24:35.340 --> 00:24:40.820 that show some lateral component. 00:24:42.580 --> 00:24:52.720 The geometry of that tell us – from the – from the aftershock, we get – 00:24:52.720 --> 00:24:57.340 those were preliminary figures that [inaudible] 00:24:57.340 --> 00:24:59.159 provided to the working group. 00:24:59.159 --> 00:25:06.130 But you can see immediately how complex is the rupture at depth. 00:25:06.130 --> 00:25:16.030 And this is – this is the area of the – so each color is – so this is Norcia, 00:25:16.030 --> 00:25:21.990 so this is the 6.5, and you can see that, in this area, it’s really – 00:25:21.990 --> 00:25:28.500 the situation is really complicated. Here you have a nice antithetic fault. 00:25:28.500 --> 00:25:36.900 And here you have some deeper seismicity, 00:25:36.910 --> 00:25:44.600 but still on – the main plane is still a plane on the – a typical Apenninic plane. 00:25:44.600 --> 00:25:51.800 So northwest-striking and southwest-dipping. 00:25:52.440 --> 00:26:03.280 Another thing you can see here are this low-angle alignment of seismicity 00:26:03.289 --> 00:26:07.419 that is always around 10 kilometers. 00:26:07.419 --> 00:26:09.370 This is something that they told me 00:26:09.370 --> 00:26:15.280 they can find also to the north a little bit, and then it disappears. 00:26:15.280 --> 00:26:20.120 So it’s not – it doesn’t exist in the L’Aquila area. 00:26:20.120 --> 00:26:29.340 And one possibility is that it represents the brittle-ductile transition. 00:26:30.260 --> 00:26:35.940 So what are the faults that were activated by this earthquake sequence? 00:26:35.950 --> 00:26:41.970 So there are two – there are two faults system. 00:26:41.970 --> 00:26:48.090 That is the Vettore-Bove and the Laga Mountain fault system. 00:26:48.090 --> 00:26:59.240 So those were known – used in some hazard calculation. 00:26:59.240 --> 00:27:04.780 And so – and we have three shocks on those. 00:27:07.100 --> 00:27:15.020 We had the surface faulting for the three – for the three main shocks. 00:27:15.020 --> 00:27:24.160 The first one – the 24th of August – just let’s go back. 00:27:24.160 --> 00:27:27.580 So surface faulting was only around this one. 00:27:27.580 --> 00:27:34.920 So even though this fault is for sure activated, 00:27:34.920 --> 00:27:49.070 at least during the August 24th event and for the 2017 January event. 00:27:50.200 --> 00:27:53.000 But surface faulting was only here. 00:27:53.000 --> 00:27:58.750 And you can see here the zone of surface faulting – so where we 00:27:58.750 --> 00:28:04.620 could map the fault at the surface – overlapping with the – 00:28:04.620 --> 00:28:10.440 with the fringes from an InSAR solution. 00:28:10.440 --> 00:28:19.640 And there was a lot of discussion here because there are some colleagues 00:28:19.640 --> 00:28:27.659 that believes that this is evidence of landsliding – a huge landslide, 00:28:27.660 --> 00:28:33.480 5 kilometer long, that is produced by the shaking. 00:28:35.980 --> 00:28:46.100 So what happened – so this is the maps, and the fact – so those ruptures, 00:28:46.100 --> 00:28:53.440 they even cut across a crest line. So they – it clearly show up 00:28:53.440 --> 00:28:58.280 that this is not a landslide, but this is a tectonic feature. 00:28:58.280 --> 00:29:00.809 Of course, you can – with normal faults, 00:29:00.809 --> 00:29:05.380 you would expect always to have some gravitational component. 00:29:07.860 --> 00:29:12.320 This shows you the zone of the rupture. 00:29:12.320 --> 00:29:16.140 And there is a very nice fault along it, 00:29:16.140 --> 00:29:21.640 so you can walk along it and be sure that this is a fault. 00:29:21.640 --> 00:29:25.299 And – okay, this was the type of ruptures. 00:29:25.299 --> 00:29:28.570 We flew over with helicopter and got many pictures. 00:29:28.570 --> 00:29:36.090 So, for example, this is – this is – this photo here, and you can see 00:29:36.090 --> 00:29:43.440 the cracks that cuts across a crest. So this is a crest. 00:29:45.660 --> 00:29:55.200 Some other – few pictures that show the 20 August 2016 where – kind of small. 00:29:55.210 --> 00:30:00.179 Just 20 centimeters maximum – I think the average 00:30:00.179 --> 00:30:04.029 is something like 13 centimeters. 00:30:04.029 --> 00:30:09.340 This is the distribution of – the red one is the vertical. 00:30:09.340 --> 00:30:14.190 The blue one is the heave – the opening. 00:30:16.240 --> 00:30:22.920 We’ll say – okay, the next – so those were the 24th ruptures – August 24th. 00:30:22.929 --> 00:30:27.240 And then to the – the second shock – main shock, 00:30:27.240 --> 00:30:33.320 the October 26 occurred to the north, and here you see the cracks. 00:30:34.580 --> 00:30:40.200 The resolution of the InSAR data is not very good for this earthquake. 00:30:40.200 --> 00:30:47.460 But anyway, we had about 7 kilometer discontinuous ruptures 00:30:47.460 --> 00:30:53.340 with the – with an average throw of 16 centimeters. 00:30:53.340 --> 00:30:57.390 So something very similar to what we observed to the south. 00:30:57.390 --> 00:31:01.900 However, the survey of those ruptures was not complete. 00:31:01.900 --> 00:31:07.580 Because a few days after – okay, the ruptures – a few days 00:31:07.580 --> 00:31:15.990 after the October 30 occurred, and of course, overprinted many of 00:31:15.990 --> 00:31:27.340 the ruptures from the 24th of August and 26th of October. 00:31:27.340 --> 00:31:35.350 So the October 30 ruptures were mapped by a large group 00:31:35.350 --> 00:31:38.920 of scientists from all Europe. 00:31:38.920 --> 00:31:46.240 And there is a map out – a general map, and all the data are available on – 00:31:46.240 --> 00:31:51.860 all the data are available on the – on the Scientific Data, I think. 00:31:51.870 --> 00:31:59.340 So you can – you are welcome to use them for studying this. 00:31:59.340 --> 00:32:10.549 What’s important here is that the October 30 ruptures overlapped and 00:32:10.549 --> 00:32:18.630 overprinted the 24th of August and 26 of October, partially, ruptures. 00:32:18.630 --> 00:32:26.760 So this was a big subject of discussion. And also, in this case, there is a group 00:32:26.760 --> 00:32:30.960 of people that claims that, because of this – you see these 00:32:30.960 --> 00:32:34.740 fringes that have different pattern? 00:32:36.640 --> 00:32:43.240 They claim there is a major component – gravitational component. 00:32:44.720 --> 00:32:47.280 Just a few slide to show you the ruptures. 00:32:47.280 --> 00:32:53.700 So the main ruptures were – okay, this is impressive, but this is only part of 00:32:53.700 --> 00:33:03.679 the rupture that is along this front fault that was very clear and well-mapped. 00:33:03.679 --> 00:33:11.950 And then you have many other ruptures all along the slope. 00:33:11.950 --> 00:33:15.100 This is a detail. 00:33:15.100 --> 00:33:19.380 And those are some other – few photographs. 00:33:20.660 --> 00:33:23.460 You can see how neat. 00:33:24.220 --> 00:33:33.400 And it’s interesting that, in this part, we have also important antithetic ruptures. 00:33:33.400 --> 00:33:39.340 And I don’t know if you can see there is a rupture here. 00:33:39.340 --> 00:33:44.809 So let’s say this picture is taken from the main fault scarp. 00:33:44.809 --> 00:33:50.880 So we are looking at the – a fault looking at us, and it’s antithetic. 00:33:50.880 --> 00:33:57.080 And you see that sometimes the antithetic ruptures are quite big. 00:33:58.680 --> 00:34:06.850 So this picture is quite nice because it shows you that – okay, before the 00:34:06.850 --> 00:34:11.719 magnitude 6 earthquake, the ground was here. 00:34:11.719 --> 00:34:16.899 You see this is a piece of ground that is still hanging on the fault plane. 00:34:16.899 --> 00:34:21.329 And then the 24th of August earthquake occurred. 00:34:21.329 --> 00:34:25.609 So you have this – the ground was moved here. 00:34:25.609 --> 00:34:31.680 And you have this – about 20-centimeter displacement. 00:34:31.680 --> 00:34:36.900 But then, at the same place, after the magnitude 6.5, 00:34:36.900 --> 00:34:41.860 you have this whole amount of slip related to this earthquake. 00:34:41.860 --> 00:34:44.860 And so now the ground is here. 00:34:44.860 --> 00:34:50.240 You can see the size of the rupture with the – with the size of the person. 00:34:50.240 --> 00:34:58.309 And this is one of our first questions. So the same fault ruptured two times 00:34:58.309 --> 00:35:03.540 in a very short period of time. So this is something we have to think about. 00:35:03.540 --> 00:35:10.820 Okay, this is the map I was telling you. You can download it. 00:35:10.820 --> 00:35:16.720 And so surface faulting occurred during the three main shocks. 00:35:16.720 --> 00:35:23.259 So the green one is surface faulting for the 24th of August. 00:35:23.259 --> 00:35:31.731 The yellow is for the 26th of October, and the red that overprinted almost 00:35:31.731 --> 00:35:41.579 completely the August event, and the 26 of October event is the red. 00:35:41.579 --> 00:35:44.070 So that is the biggest one. 00:35:44.070 --> 00:35:48.700 If we compare the average displacement we observed 00:35:48.700 --> 00:35:53.749 and the size of – the magnitude of earthquake, they fit within 00:35:53.749 --> 00:35:59.780 the classical empirical relationships by Wells and Coppersmith. 00:36:02.420 --> 00:36:14.320 Okay, so this is – those are the slip – the displacement measured in the field. 00:36:14.320 --> 00:36:18.700 And you can – each color represents a different strand of the fault. 00:36:18.700 --> 00:36:24.320 So this gives already a touch with the complexity of – 00:36:24.329 --> 00:36:27.309 at least of the geology we have. 00:36:27.309 --> 00:36:33.719 And those are the antithetic ruptures that are quite important in this area. 00:36:33.719 --> 00:36:38.880 You see they are more or less the same – the same amount. 00:36:38.880 --> 00:36:43.100 And let’s see what is the contribution to those ruptures. 00:36:44.400 --> 00:36:48.619 So that was the sum of the three events. And the contribution 00:36:48.619 --> 00:36:55.000 of the ruptures are – you see for the 24th of August is this blue one. 00:36:55.000 --> 00:36:57.890 The 26th of October, the green one. 00:36:57.890 --> 00:37:05.080 And the 6.5 October 30 is this big red rupture. 00:37:05.900 --> 00:37:10.300 And it’s interesting to notice that the big rupture – 00:37:10.300 --> 00:37:19.040 the 30 of October – coincide with what is the highest slip at depth. 00:37:20.080 --> 00:37:25.780 And it coincides with – our highest peak coincide also 00:37:25.790 --> 00:37:30.359 with the part that is more superficial. 00:37:30.359 --> 00:37:34.480 And notice that this red is about 2 meter and a half. 00:37:34.480 --> 00:37:39.940 So the slip is quite high and concentrated. 00:37:39.940 --> 00:37:46.869 Okay, this is a – [chuckles] – it’s a kind of a puzzle, but anyway, 00:37:46.869 --> 00:37:53.650 we measured – we tried to compare what were the ruptures – 00:37:53.650 --> 00:38:00.640 the coseismic rupture – with the long-term evidence of the fault. 00:38:00.640 --> 00:38:07.420 And we made all this – several profiles across the ruptures 00:38:07.430 --> 00:38:15.130 or the faults, both for measuring just the geomorphology – 00:38:15.130 --> 00:38:20.550 so the top surface – and the – and the geology. 00:38:20.550 --> 00:38:27.760 So what it came out is a – is a trend like this with some low. 00:38:27.760 --> 00:38:34.080 So that means that those – because those are cumulative 00:38:34.080 --> 00:38:42.979 geologic and geomorphic throw, those low show you that you have – 00:38:42.979 --> 00:38:47.680 you may have, in that area, repeated low in your ruptures. 00:38:47.680 --> 00:38:53.920 And they may represent some indication of internal complexity – 00:38:53.920 --> 00:38:59.680 boundary of sections or segments, as you want to call. 00:38:59.680 --> 00:39:08.859 And we compared them with the – with the throw – the coseismic throw. 00:39:08.859 --> 00:39:14.220 And we find out that this – the zone that we were – 00:39:14.220 --> 00:39:22.039 we did interpret as potential segmentation. 00:39:22.039 --> 00:39:28.979 So this is – so they don’t fit completely with the coseismic. 00:39:28.979 --> 00:39:35.079 So those maybe are – have been – so are in – the two part of the fault are 00:39:35.079 --> 00:39:40.619 probably interacting in different ways. They may have – anyway, they – 00:39:40.619 --> 00:39:46.030 in both cases, we can say we are looking at some interaction that can 00:39:46.030 --> 00:39:55.200 be linked in different way – hard link and soft link as you like. 00:39:55.200 --> 00:39:59.460 But anyway, there may be something going on here. 00:39:59.460 --> 00:40:06.630 And maybe, in the long-term, they will be completely erased and changed. 00:40:06.630 --> 00:40:14.580 But, for the moment, what we see is that there may be a kind of link like this one. 00:40:14.580 --> 00:40:19.200 And, in fact, they ruptured together in one event. 00:40:19.200 --> 00:40:24.539 Another thing that we are wondering about is that, okay, this is – 00:40:24.539 --> 00:40:31.559 this is the Monte Vettore that had the surface faulting, and we tried to 00:40:31.559 --> 00:40:36.640 investigate the internal complexity. And this is the Laga Mountains. 00:40:36.640 --> 00:40:42.359 And so this is the long-term cumulative throw. 00:40:42.360 --> 00:40:50.620 And you can see that they are kind of specular and asymmetric. 00:40:50.620 --> 00:40:58.260 And they may – they may be in a situation like this one, 00:40:58.260 --> 00:41:01.880 with a little overlap between them. 00:41:03.280 --> 00:41:14.150 This one – this part ruptured during the 6.0 event but didn’t rupture the surface. 00:41:14.150 --> 00:41:22.680 So maybe this linkage is effective, but not enough to rupture the 00:41:22.680 --> 00:41:27.819 whole segment to the south. But we are wondering whether we 00:41:27.820 --> 00:41:35.280 can have the rupture of the two segments together with a – with a bigger 00:41:35.280 --> 00:41:47.259 rupture – bigger total [inaudible] rupture, so higher magnitude and so on. 00:41:47.259 --> 00:41:53.039 Here we are looking at the coseismic slip calculated 00:41:53.039 --> 00:41:58.910 from ground motion data for the 2009 earthquake. 00:41:58.910 --> 00:42:09.440 And for the – all the main shock for the 2016 and also for the 00:42:09.440 --> 00:42:15.190 magnitude 5 that occurred in January ’17. 00:42:15.190 --> 00:42:19.449 You can see that, okay, this area had big ruptures. 00:42:19.449 --> 00:42:24.269 The black one is more than 2 meters. Whoops, sorry. 00:42:24.269 --> 00:42:26.620 The black one is more than 2 meters. 00:42:26.620 --> 00:42:31.860 And, okay, the modelers were not very happy with this. 00:42:31.869 --> 00:42:36.420 They said that their solutions were not very good, especially for the 00:42:36.420 --> 00:42:41.329 Norcia earthquake. But here I want you to notice that, okay, 00:42:41.329 --> 00:42:48.769 those ruptures are for the 24th of August. And they – and this part 00:42:48.769 --> 00:42:55.260 of the fault ruptured two times in two – at the distance of two months. 00:42:55.260 --> 00:42:59.519 The other thing to notice is that this area still remain 00:42:59.520 --> 00:43:03.060 an area with low slip released. 00:43:03.060 --> 00:43:08.940 We don’t have a particularly large historical earthquake to say 00:43:08.940 --> 00:43:15.690 that the slip was already released. So we are kind of worried for this area. 00:43:15.690 --> 00:43:22.019 Also because here, Campotosto, there is a – exactly on the fault line, 00:43:22.019 --> 00:43:28.890 there is a dam that was built in 1933 – something like this. 00:43:28.890 --> 00:43:39.019 And so it’s quite – it’s quite scary. Anyway, the modelers tried to put 00:43:39.019 --> 00:43:46.489 GPS and InSAR data together to see if they could understand better 00:43:46.489 --> 00:43:55.040 the complexity of this event. So they tried to use the geometry 00:43:55.040 --> 00:43:59.360 that were coming out from the aftershock data. 00:43:59.360 --> 00:44:06.211 And they tried with an antithetic fault. They tried with two sub-parallel fault – 00:44:06.211 --> 00:44:11.099 one with the lower angle. There is a lot of attention here 00:44:11.099 --> 00:44:18.140 on the possibility that faults, especially [inaudible] related to the compressional 00:44:18.140 --> 00:44:27.949 activity, are re-used and re-activated during those earthquake as normal faults. 00:44:27.949 --> 00:44:30.900 This is another model. So what they did – 00:44:30.900 --> 00:44:38.780 they took the geological data, and this is a ramp of major thrust. 00:44:40.260 --> 00:44:52.020 And they looked also at some peculiarities in the – 00:44:52.020 --> 00:44:57.360 in the aftershock data, and they came out with a model like this. 00:44:57.369 --> 00:45:00.609 So you have a – for this 6.5 event, 00:45:00.609 --> 00:45:06.340 you have a main fault that is the northwest-striking fault. 00:45:06.340 --> 00:45:13.680 And a fault – the secondary fault that is almost perpendicular. 00:45:13.680 --> 00:45:17.640 And those ruptured together. So this is their model. 00:45:17.640 --> 00:45:31.100 You see you have this high-slip area that would be on a plane that is 90 degree. 00:45:31.100 --> 00:45:37.320 And this is – so this is the intersection. So they were very happy with this 00:45:37.329 --> 00:45:43.569 model that is here represented very simplified in 3D. 00:45:43.569 --> 00:45:50.979 But this is also to show that – this is the green rupture that is the 5.9. 00:45:50.979 --> 00:45:59.190 The yellow is something like – up to here that is the 24th of August – the 6. 00:45:59.190 --> 00:46:03.479 And this is the red. So you see that you have ruptures 00:46:03.479 --> 00:46:13.359 on same four planes during the – with the individual main shocks. 00:46:13.359 --> 00:46:19.030 So this is not – so this complex – it is not new for Italy. 00:46:19.030 --> 00:46:24.660 And actually, the recent normal faulting earthquakes in the Apennines 00:46:24.660 --> 00:46:30.569 always open some new questions. So this is the Irpinia. 00:46:30.569 --> 00:46:34.130 And you see we had the four main shock in 40 seconds. 00:46:34.130 --> 00:46:40.309 So each one of these is a – it can be an individual section 00:46:40.309 --> 00:46:43.420 of the fault that may go by itself. 00:46:43.420 --> 00:46:49.319 This is the Umbria-Marche – 1997. Three main shocks in days. 00:46:49.320 --> 00:46:55.820 So those were in – those two in few hours, and this a few days after. 00:46:55.820 --> 00:47:00.880 And the L’Aquila had one main shock. 00:47:00.880 --> 00:47:05.559 But the interesting thing is that we recognize the longer fault. 00:47:05.559 --> 00:47:12.549 So the fault segment is much longer than the part that ruptured during this event. 00:47:12.549 --> 00:47:17.520 And this is this case here. So each earthquake is quite different. 00:47:17.520 --> 00:47:24.760 But all of them seems to have a strong – strongly interacting with 00:47:24.760 --> 00:47:30.040 pre-existing structures related to the build-up of the Apennines. 00:47:31.280 --> 00:47:35.440 Another question is, okay, we have also in the historical catalog, 00:47:35.449 --> 00:47:42.579 we have many multiple events – multiple-shocks events. 00:47:42.579 --> 00:47:49.939 So we are thinking, oh, maybe all this tell us that they are complex events. 00:47:49.939 --> 00:47:57.190 So they may be ruptures that interacted with the pre-existing features. 00:47:57.190 --> 00:48:00.499 And they broke apart in smaller pieces, 00:48:00.499 --> 00:48:06.180 and so they went into few months or so. 00:48:06.180 --> 00:48:10.410 So this is something we have to look at, but of course, 00:48:10.410 --> 00:48:17.049 it’s clear that the present-day structure of Italy, 00:48:17.049 --> 00:48:22.779 it’s dominated by those thrust and compressional features. 00:48:22.779 --> 00:48:28.029 But the active – the most active faults are normal. 00:48:28.029 --> 00:48:32.600 So there should be an overlap between the two stories. 00:48:32.600 --> 00:48:37.320 And what I should tell you is that the Apennines 00:48:37.320 --> 00:48:41.580 are a quite recent mountain chain. 00:48:41.580 --> 00:48:45.560 And the changes in – between compressional and 00:48:45.569 --> 00:48:50.479 extensional in Apennines is younger than 2 million years. 00:48:50.479 --> 00:48:52.359 So this may have an impact. 00:48:52.359 --> 00:48:58.650 So we are still – our normal faults are still building up and probably 00:48:58.650 --> 00:49:05.979 connecting and linking one to each other to form a through-going rupture. 00:49:05.979 --> 00:49:15.799 I’ll go fast, but I want to say that this highlight for us – with geologists, 00:49:15.799 --> 00:49:21.099 this highlight – question. What we see in the trenches. 00:49:21.099 --> 00:49:25.390 So we – you know, we cannot have a thousand of trenches, 00:49:25.390 --> 00:49:34.609 and so it’s quite tough to build up a very precise history of the – 00:49:34.609 --> 00:49:36.489 of the different sections of the fault. 00:49:36.489 --> 00:49:41.229 For example, this is the famous Irpinia trench that I excavated – 00:49:41.229 --> 00:49:44.440 I had the honor to excavate with David. 00:49:44.440 --> 00:49:52.569 Very nice story. We have five events, including the 1980. 00:49:52.569 --> 00:49:57.320 We have two sides. One in this section and another one in this section. 00:49:57.320 --> 00:50:01.820 The edges can overlap, so we can say that, apart for 00:50:01.829 --> 00:50:07.099 this event, all the ages overlap. So we may say, okay, this is the 00:50:07.100 --> 00:50:13.680 same event, and the 1980 earthquake is typical for this fault. 00:50:13.680 --> 00:50:23.680 But because of the big – the wide range of uncertainty 00:50:23.680 --> 00:50:28.029 on edges, we cannot really be sure of this. 00:50:28.029 --> 00:50:31.779 So we should think – I’m sure the dating can be 00:50:31.779 --> 00:50:37.519 much better now than at that time. But anyway, this is just to say, 00:50:37.520 --> 00:50:43.500 okay, we have many things to think about and to work on. 00:50:46.480 --> 00:50:51.640 And merging seismology and also geology and geodesy 00:50:51.650 --> 00:50:56.170 can be the only way to approach those problems. 00:50:56.170 --> 00:51:03.499 I just want to show you – okay, those were the ruptures of the – 00:51:03.500 --> 00:51:07.700 of the – that we saw on the mountain range. 00:51:07.700 --> 00:51:13.000 And then the ruptures were going here on the – on this valley. 00:51:13.000 --> 00:51:18.760 And this is a trench that was open around 2000. 00:51:18.760 --> 00:51:26.640 And the trench was open where today – after the 2016, we had this little rupture 00:51:26.641 --> 00:51:34.609 in the middle of this plane. So this was – it’s a detail of the trench. 00:51:34.609 --> 00:51:39.120 And the trench was excavated by Galli and Galadini. 00:51:39.120 --> 00:51:45.699 And they expected the magnitude – the 6.5, and they say, oh, this fault, 00:51:45.700 --> 00:51:52.980 maybe it’s ready to go because the elapsed time is 13 – 1,500 years. 00:51:52.980 --> 00:51:56.360 So they did well. So this was a good guess. 00:51:56.360 --> 00:52:01.040 What we are doing today is to – trying to understand better, 00:52:01.059 --> 00:52:06.040 and we would like to understand if this fault can rupture in bigger events. 00:52:06.040 --> 00:52:13.420 So linking the two segments – the southern one and the northern one. 00:52:13.900 --> 00:52:23.380 And if we can find some other stories like the smaller events and larger 00:52:23.380 --> 00:52:31.130 event like in 2016. So we tried to – we are starting a trench campaign. 00:52:31.130 --> 00:52:34.700 But we are working – for the moment, we are working only on the 00:52:34.700 --> 00:52:39.020 antithetic ruptures that are here. You see these yellow points. 00:52:39.020 --> 00:52:45.760 Because the main faults are high in the mountains or in places 00:52:45.769 --> 00:52:50.079 that are not really good. Anyway, this is – you see the ruptures. 00:52:50.080 --> 00:52:53.440 And the small trench here. 00:52:53.440 --> 00:53:06.600 This is some high-resolution – how you say – [inaudible] station. 00:53:06.600 --> 00:53:11.220 And, okay, this is old-style mapping of the faults. 00:53:11.220 --> 00:53:15.019 And you see the structure is very complicated, 00:53:15.019 --> 00:53:22.910 but [Francesca] was so good to find evidence for two events before 2016. 00:53:22.910 --> 00:53:26.520 So this is another – so the rupture runs here. 00:53:26.520 --> 00:53:32.260 The scarp [inaudible] this little valley, so we were very happy to put the 00:53:32.270 --> 00:53:37.940 trench here in the middle of the valley. But someone else excavated it before us. 00:53:37.940 --> 00:53:43.710 So anyway, the trench was in an [inaudible] stratigraphy, but also here, 00:53:43.710 --> 00:53:48.849 they found evidence for a previous event and some dating. 00:53:48.849 --> 00:53:51.920 And this is another trench that is quite interesting. 00:53:51.920 --> 00:53:55.150 So this place, though, was not rupture at the surface. 00:53:55.150 --> 00:54:01.439 The rupture was some – to the south, and there is more cracks. 00:54:01.439 --> 00:54:06.849 But from geophysics, we found that there was a displacement at that. 00:54:06.849 --> 00:54:12.400 So we did open the trench. And what we found out is that 00:54:12.400 --> 00:54:17.229 no younger ruptures occurred here. And the deposits are quite old. 00:54:17.229 --> 00:54:22.170 So this was good because, from that trench, we got old events. 00:54:22.170 --> 00:54:24.690 From the previous trenches, we got the young events. 00:54:24.690 --> 00:54:29.920 So in this way, we have a very preliminary idea of the fact that, 00:54:29.920 --> 00:54:38.059 in 18,000 years, we had at least seven events on the antithetic fault. 00:54:38.059 --> 00:54:41.759 And the antithetic fault moved only for the 6.5. 00:54:41.760 --> 00:54:44.700 So that’s something to begin. 00:54:44.700 --> 00:54:54.239 But we should think, really, about what we can do with those earthquakes. 00:54:55.340 --> 00:55:00.410 Okay, I already told this. And so I want to thank you 00:55:00.410 --> 00:55:06.119 for your attention, and I should thank all my colleagues at INGV 00:55:06.120 --> 00:55:12.140 because they did most of the work. I’m lazy now with science. 00:55:12.140 --> 00:55:14.800 [laughter] 00:55:15.400 --> 00:55:20.320 [Applause] 00:55:20.660 --> 00:55:22.840 - Thanks, Daniela. Questions? 00:55:26.740 --> 00:55:29.560 [inaudible] 00:55:30.720 --> 00:55:35.560 [Silence] 00:55:36.260 --> 00:55:38.680 - Daniela, does the seismicity tell you much 00:55:38.680 --> 00:55:41.880 about how the faults connect at depth? 00:55:42.760 --> 00:55:47.900 And let me add, what is that surface offset between the two segments? 00:55:48.400 --> 00:55:51.489 - Oh, it’s very small. It’s very small. 00:55:51.489 --> 00:55:54.780 We can – we can go back and look at it. 00:55:55.640 --> 00:56:07.400 [Silence] 00:56:08.260 --> 00:56:11.960 Almost there. Don’t worry. [laughs] 00:56:13.040 --> 00:56:16.700 [Silence] 00:56:17.220 --> 00:56:24.939 Okay. This cartoon show you that – this is the offset. 00:56:24.940 --> 00:56:37.940 There are – what is important here is that there is this – how do you say – 00:56:37.940 --> 00:56:42.859 a ramp in between those two segments. So this segment boundary 00:56:42.859 --> 00:56:46.299 was placed because of this. And I would say that the offset 00:56:46.300 --> 00:56:50.840 is probably 2, 3 kilometers. - Okay, so not much. 00:56:51.600 --> 00:56:55.080 What does the seismicity tell you about how those faults [inaudible]? 00:56:57.280 --> 00:57:03.020 - Okay. So there is this paper from [inaudible] et al. 00:57:03.029 --> 00:57:06.179 that I think is out in JJR. 00:57:06.179 --> 00:57:17.069 And they show that – from – also from the seismicity, you can see that ramp. 00:57:17.069 --> 00:57:24.789 So probably that’s the reason for this step and for the fact that the rupture – 00:57:24.789 --> 00:57:32.849 the 24th rupture ruptured the other part but didn’t rupture the whole. 00:57:32.849 --> 00:57:36.760 Because that ramp didn’t go immediately. 00:57:37.540 --> 00:57:43.940 [Silence] 00:57:44.820 --> 00:57:48.959 - So when are you inviting us all over to Italy to help you out? 00:57:50.640 --> 00:57:53.700 These were – these were moderate-magnitude, 00:57:53.700 --> 00:57:57.360 relatively short rupture-length events. 00:57:58.720 --> 00:58:03.249 L’Aquila falls into that category. You go a little further south, 00:58:03.249 --> 00:58:07.489 you have 1915 [inaudible], which was a larger magnitude, 00:58:07.489 --> 00:58:11.280 larger displacement, somewhat longer rupture. 00:58:11.280 --> 00:58:14.980 And you’ve also done a lot of paleoseismology on other faults 00:58:14.989 --> 00:58:18.219 in the Apennines. Do you have a feeling for 00:58:18.220 --> 00:58:25.840 how large an earthquake the Apennine zone of extension can generate? 00:58:27.620 --> 00:58:31.680 - Well, if we believe – so, from the displacement 00:58:31.680 --> 00:58:36.819 in the trenches, I cannot say. Because here, you see the variability 00:58:36.819 --> 00:58:45.579 of the ruptures, both for the – for a magnitude 6 and for the magnitude 6.5. 00:58:45.579 --> 00:58:51.920 You go from 2 meters up to 30 centimeters. 00:58:51.920 --> 00:59:00.890 So it’s really hard to – of course, you can understand from the long-term geology 00:59:00.890 --> 00:59:07.180 and long-term geomorphology if you are in an area of a larger slip or small slip. 00:59:07.180 --> 00:59:13.940 But because we saw that there is – there is a mimicking shape in the – 00:59:13.940 --> 00:59:16.520 in the coseismic and long-term. 00:59:17.260 --> 00:59:23.920 But we played mainly on these segments that we were 00:59:23.930 --> 00:59:29.170 trying to draw – so the maximal length. 00:59:29.170 --> 00:59:38.469 And what it come out is that apparently we cannot go more than 7. 00:59:38.469 --> 00:59:42.849 But there are always a lot of complexities, 00:59:42.849 --> 00:59:50.480 so we see that between 6 and 7, it’s the most common. 00:59:51.900 --> 00:59:54.760 - That would be based on … - On length. 00:59:54.760 --> 00:59:57.020 - … length at the surface. - Yeah. 00:59:57.020 --> 01:00:02.779 - And then coming back to the point that Tom raised, the possibility of there 01:00:02.780 --> 01:00:09.190 being connections at depth, which increase the potential rupture length. 01:00:10.060 --> 01:00:15.319 - No, I think the fragmentation is very high. 01:00:15.320 --> 01:00:25.260 So one hypothesis was done for the 1456 earthquake that occurred 01:00:25.260 --> 01:00:30.569 in several – so apparently now is split in several shocks. 01:00:30.569 --> 01:00:36.300 But the one idea was it was a 400-kilometer-long rupture. 01:00:36.300 --> 01:00:42.559 But then, studying better the historical documents, 01:00:42.560 --> 01:00:45.809 they splitted in several shocks. 01:00:46.400 --> 01:00:51.480 Because, you know, at that time, timing is something very debatable. [laughs] 01:00:51.480 --> 01:00:56.060 So even the day can be wrong and things like this. 01:00:56.069 --> 01:01:01.650 But that is something that occurred very quickly, but there are some – 01:01:01.650 --> 01:01:06.729 also some transversal faults involved. This is an interpretation. 01:01:06.729 --> 01:01:13.100 It’s not – you know, you live with interpretation on those type of things. 01:01:14.720 --> 01:01:19.559 But I’m not expecting a whole rupture on the whole Apennines. 01:01:19.559 --> 01:01:22.579 I don’t believe it’s – [chuckles] … - Well, if you do, 01:01:22.580 --> 01:01:27.240 we’ll have you work on UCERF4. - Yeah. [laughs] 01:01:28.620 --> 01:01:36.200 [Silence] 01:01:36.880 --> 01:01:41.640 - Maybe you’ve answered this question, Daniela, but is the kind of complexity 01:01:41.640 --> 01:01:48.460 that you described in detail for these earthquakes in 2016, 01:01:48.460 --> 01:01:51.270 if you went anywhere else on the Apennines, would you see 01:01:51.270 --> 01:01:52.999 this same kind of complexity? 01:01:53.000 --> 01:02:01.400 Or is the surface distribution of small faults simpler in some areas? 01:02:02.640 --> 01:02:05.859 - No, I would say the complexity is very similar. 01:02:05.860 --> 01:02:10.660 We tried to simplify it. Because without having an earthquake, 01:02:10.660 --> 01:02:17.140 you try to make the easiest – the simplest model as possible. 01:02:17.140 --> 01:02:24.700 And so we tried to put together splays of faults that can rupture in one go. 01:02:25.600 --> 01:02:34.079 In general, those faults are 2, 5 – 2, 3, 5 kilometers long that you put together. 01:02:34.079 --> 01:02:40.410 So in some cases, some are inherited from previous tectonics. 01:02:40.410 --> 01:02:44.619 So it’s clear that maybe they have a nice 01:02:44.620 --> 01:02:50.620 small basin connected because it’s inherited. 01:02:51.260 --> 01:02:56.200 But in many cases, those faults crosses across mountain ranges and 01:02:56.209 --> 01:03:02.310 changes a lot, the geomorphology where they are located, because – 01:03:02.310 --> 01:03:06.829 exactly because it’s something new that is trying to build up. 01:03:06.829 --> 01:03:14.289 So I have the feeling that we have all these little pieces of faults that are 01:03:14.289 --> 01:03:21.060 getting under this extension. And sometimes they go together. 01:03:21.060 --> 01:03:25.600 And in the long run, you can have longer faults. 01:03:25.600 --> 01:03:27.500 - Thank you. 01:03:28.980 --> 01:03:33.320 [Silence] 01:03:34.160 --> 01:03:37.880 - Hi, Danila. Thank you for this talk. Good to see you again. 01:03:37.880 --> 01:03:43.780 And what you raised – there’s an interesting question there. 01:03:43.780 --> 01:03:48.249 It sounds like you almost said that the topography is really 01:03:48.249 --> 01:03:54.259 not well-aligned with the modern fault system, or vice versa. 01:03:54.259 --> 01:03:59.019 Unlike something like the Basin and Range, where you’re going to always 01:03:59.019 --> 01:04:02.959 find the faults at the base of the mountain ranges, or most of the time. 01:04:02.959 --> 01:04:06.049 This is rather different. The faults kind of go wherever 01:04:06.049 --> 01:04:11.959 they want [laughs] without regard to the topography or maybe even 01:04:11.959 --> 01:04:17.670 the existing geologic structure. Is that correct? 01:04:17.670 --> 01:04:25.009 - Yes. They go where they want, but we have evidence that they 01:04:25.009 --> 01:04:33.880 want to – they choose their location – repeated the rupture in the same places. 01:04:33.880 --> 01:04:39.339 And probably the Irpinia earthquake fault is one of the 01:04:39.339 --> 01:04:48.089 most clear evidence for this. Because we have this fault that is 01:04:48.089 --> 01:04:55.299 dipping against the slope of the mountain that is crossed by this. 01:04:55.299 --> 01:04:59.609 So this fault is not at the base of the range. 01:04:59.609 --> 01:05:06.920 But it’s not even dipping as the slope, as you would expect for a normal fault, 01:05:06.920 --> 01:05:13.339 but it’s dipping. So we have a range that is dipping to the southwest, 01:05:13.340 --> 01:05:19.620 and the fault is dipping to the northeast. So it’s reversing topography. 01:05:19.620 --> 01:05:25.680 But it will take, I don’t know, a million years to have a basin. 01:05:26.580 --> 01:05:30.480 - So these faults are not going where David Schwartz wants them to go. 01:05:30.480 --> 01:05:32.520 [laughter] 01:05:34.260 --> 01:05:38.320 - That’s so often the case. [laughter] 01:05:41.040 --> 01:05:42.780 - Okay, well, thank you, everyone, for coming this morning. 01:05:42.780 --> 01:05:44.500 [Applause] 01:05:44.500 --> 01:05:45.780 - And thank you, Daniela. - Thank you. 01:05:45.780 --> 01:05:48.400 [Applause] 01:05:48.400 --> 01:05:52.840 [Silence]