Italy’s deadly earthquake – scientists respond

Italy’s deadliest earthquake in nearly three decades has killed at least 150 people, left tens of thousands homeless and smashed treasured historical buildings that had stood for centuries.

The 6.3-magnitude quake was centred 95km north of Rome and struck at 3.22am.

The British Science Media Centre has rounded up comment on the quake from earthquake experts.

An Italian scientist living in the quake-struck zone claims he predicted the earthquake but that his pleas to the Italian authorities to prepare for it were ignored.

Italy's earthquake zones

John Whalley, Principal Lecturer, School of Earth and Environmental Sciences, University of Portsmouth, said:

“The earthquake occurred in an area with a significant history of seismic activity. There is a belt of seismicity that roughly parallels the line of the Apennine mountain chain, running along the length of the Italian peninsula.

“These mountains form part of the major tectonic plate boundary marking the collision zone between the African and European plates. This collision dominated the geological evolution of Southern Europe for most the last 50 million years and in so doing formed the Alps.

“Though we speak of a collision between two major plates, the collision zone is extremely complex with numerous microplates being trapped as the intervening ocean closed. As a consequence of this complexity, the Apennines run almost at right angles to the main trend of the Alps, having been formed when the western half of Italy was pushed over the top of the eastern half. Although the primary west to east motion has largely ceased, the area remains extremely unstable and hence prone to earthquakes.

“A magnitude 6.3 earthquake will nearly always be strong enough to cause significant damage but work published in 2005 (see reference below) highlighted an increased risk in this area. The authors showed that the city was underlain by weak sediments, up to 250m thick, which had accumulated in an ancient lake. These sediments would cause amplification of the vibrations of an earthquake and so could increase the intensity of surface damage.”

Evidence of low-frequency amplification in the city of L’Aquila, central Italy, through a multidisciplinary approach including strong- and weak-motion data, ambient noise, and numerical modeling.
Authors:                De Luca Gaetano; Marcucci Sandro; Milana Giuliano; Sano Tito.
Source:                  Bulletin of the Seismological Society of America. 95; 4, Pages: 1469-1481; 2005.

Dr Metin Basoglu, Head of Section of Trauma Studies at the Institute of Psychiatry of King’s College London, said:

“More than 1 in 3 earthquake survivors are likely to need urgent psychological help for fear of further earthquakes and related traumatic stress problems. Large numbers of survivors can be helped by using an effective and cost-effective self-help-model of mental health care that we developed after the 1999 earthquakes in Turkey (more information can be found at www.dabatem.org).”

Prof Bob Holdsworth, Professor of the Reactivation Research Group and Head of Earth Sciences at Durham University, said:

“The location of the earthquake lies along the Apennine backbone of Italy, a region where recently created mountains are now slowly collapsing due to a complex large-scale interaction between plate tectonic forces and gravity.

“The evidence for these earthquakes is everywhere in Italian life, ranging from cataclysmic events recorded throughout human history and legend through to the steep, cliff-like fault scarps that can be traced across the landscape.”

Scarp features – often many tens of kilometres long – are geological scars showing where the huge faults responsible for many of the earthquakes have torn through the surface of the Earth in recent times. Scientists from the universities of Durham, Edinburgh, and UCL Birkbeck, funded by the Natural Environmental Research Council (NERC), are using these fault scarps to establish the history of earthquakes on faults in the Abbruzzo region of Italy, including the L’Aquila fault that is probably to blame for today’s disaster. A Durham University laser scanner is being used to create cm-resolution three-dimensional ‘photocopies’ of the fault surfaces. These results are combined with radiometric dating of crushed rocks and computer modelling of fault growth processes, allowing the team to constrain slip histories along each scarp.

Professor Holdsworth added: “The results may hold the key to understanding and predicting both the timing and likely magnitude of future earthquakes in this, and many other seismically active regions of the world.

“In this way, Earth Scientists are using a range of new techniques and approaches to reconstruct past events more accurately and therefore better predict the future.”

Prof Bill McGuire, Director, Aon Benfield UCL Hazard Research Centre, said:

“Central Italy is a region familiar with strong earthquakes and a magnitude 6 quake 80 km north of today’s event took 11 lives and damaged thousands of buildings in 1997. Today’s quake is the result of the rupture of a fault caused by the crust of central Italy being slowly pulled apart.

“The event reinforces the point that if buildings are not sufficiently well constructed, moderate earthquakes can be lethal even in the most developed nations.”

Dr Roger Musson, Seismologist at The British Geological Survey, said:

“Today’s earthquake occurs in the central part of a belt of seismicity extending the length of the Apennine Mountains in Italy. This area has been subject to destructive earthquakes throughout Italy’s long history; an earthquake near Avezzano in 1915 (about 40 km south of today’s earthquake) killed around 30,000 people and was one of the deadliest European earthquakes of the 20th Century. The underlying cause is the north-eastward movement of a crustal microplate that underlies the Adriatic Sea – this produces tensional stresses that pull apart the rocks that make up the Apennine Chain.

“The earthquake locates about 75 km south-east of the Umbria-Marche earthquakes in 1997, and locates in about the same place as the 2 February 1703 Aquilano earthquake (6.7 in magnitude), which may have been caused by the same fault. Routine earthquake prediction is not possible anywhere in the world. Given the chaotic nature of earthquake occurrence, it may never be possible. In the case of the L’Aquila earthquake, some warning might have been taken by the series of foreshocks that preceded it – though there is no way to discriminate between foreshocks and normal small-magnitude seismicity, other than with the benefit of hindsight. Aftershock activity has been intense so far. On the basis of past seismicity in this area, the possibility of a further event of similar magnitude cannot be ruled out. More information is available at: www.earthquakes.bgs.ac.uk.”

Dr David Rothery, Senior Lecturer in Earth Science, Open University, said:

“Earthquakes in Italy are not unusual. The whole region is riddled with faults as a result of the tectonic collision between Africa and Europe. A magnitude 6.0 quake in the same region in 1997 took 11 lives and destroyed 80,000 homes.
“Today’s quake at 01:32 GMT was moderately large but more significantly shallow – its depth is preliminarily estimated at only 10 km – so the shaking that it caused at the surface was large. I see from the news that 27 are confirmed dead, and I expect the death toll will rise. Italian colleagues who arrived today from Rome and Padova for the same meeting as me felt the quake for themselves. Fabrizio, my colleague from Rome, was already awake, and according to him his house shook for 20 seconds.

“See here http://earthquakes.usgs.gov/eqcenter/eqinthenews/2009/us2009fcaf/ for a map of the location and the intensity of ground shaking.

“Thousands of homes have been damaged. I wait to learn how many schools have collapsed, which is a common cause of tragedy (see http://www.open2.net/blogs/scitechnature/index.php/c52/?blog=7 ) such as last May’s magnitude 7.9 quake in SW China, because classrooms have large and often inadequately supported roofs. Further south in Italy, a smaller quake hit San Giuliana di Puglia in 2002 where poor-quality masonry walls and a heavy reinforced concrete roof contributed to the collapse of the school killing 22 children although the rest of the town was scarcely damaged. Fortunately this time the quake struck at night while the schools were empty.”