Images courtesy of Google Earth (top), and USGS (bottom). Magnitude 6.2, CENTRAL ITALY Wednesday, 24th August, 2016 at 01:36 UTC Earthquake location & overview AFGHANISTAN PAKISTAN INDIA A magnitude 6.2 (Mw) earthquake struck Central Italy, approximately 45 km North of the town of L’Aquila where a destructive magnitude 6.3 earthquake occurred in April 2009. The earthquake occurred at 10 km depth on a crustal fault in the Apennine region in central Italy. The relatively shallow depth of the earthquake has meant that this earthquake has been particularly destructive, killing at least 247 people. Pakistan Images courtesy of Google Earth (top), and USGS (bottom).

Image courtesy of US Geological Survey. Magnitude 6.2, CENTRAL ITALY Wednesday, 24th August, 2016 at 01:36 UTC Shaking caused There was Strong (VI) to very strong (VII) shaking in much of Central Italy, while the earthquake was felt throughout the country. Image courtesy of US Geological Survey.

Historical seismicity Interferogram from insarap.org Magnitude 6.2, CENTRAL ITALY Wednesday, 24th August, 2016 at 01:36 UTC Historical seismicity The central Mediterranean is a complex and tectonically active region. As many of the earthquakes are in the crust, and the area is highly populated many of these earthquakes have a human impact. Notably the L'Aquila earthquake in April 2009 which killed at least 308 people. The 2009 earthquake was preceded by several foreshocks and was linked with a high profile court case claiming that the authorities had failed to warn locals of the hazard. M 6.2 24/08/2016 M 6.3 06/04/2009 Interferogram from insarap.org

Below: Diagram showing the normal faulting mechanism of a earthquake. Magnitude 6.2, CENTRAL ITALY Wednesday, 24th August, 2016 at 01:36 UTC Earthquake mechanism The Norcia earthquake occurred on the 24th August 2016 is the result of a normal faulting structure in the central Apennines. This region is tectonically and geologically complex, involving both subduction of the Adria micro-plate beneath the Apennines from east to west, continental collision between the Eurasia and Africa plates building the Alpine mountain belt further to the north and the opening of the Tyrrhenian basin to the west. Left: Focal mechanism of the earthquake showing normal faulting (from the USGS) Below: Diagram showing the normal faulting mechanism of a earthquake.

Tectonic setting Magnitude 6.2, CENTRAL ITALY Wednesday, 24th August, 2016 at 01:36 UTC Tectonic setting The Mediterranean region has active seismicity primarily because of the northward motion of the African plate, causing the closure of the Tethys Ocean, and subduction of the Tethys plate. The convergence rate varies from 4 to 10 mm/yr along the boundary. The Apennine mountains of Southern Italy have a high risk of earthquakes due to the Subduction of the Mediterranean Sea floor beneath the Tyrrhenian Sea . There are also some active volcanoes located there above intermediate depth earthquakes. Above: Map showing the location of the collision plate boundary fault and the earthquake

Satellite images of earthquake deformation Magnitude 6.2, CENTRAL ITALY Wednesday, 24th August, 2016 at 01:36 UTC Satellite images of earthquake deformation The dimensions and amount of slip caused by the earthquake source, can be inferred using seismic and geodetic observations. Figure on the right shows the permanent displacements caused by the earthquake, as observed by the Japanese radar interferometric satellite ALOS-2. Each change in color represents 12 cm of displacement. Ground shaking correlates with the characteristics of the rupture. The rupture of shallow faults, like this Italian earthquake, produces strong shaking near the earthquake source. Credits: US Geological Survey, and Japanese Space Agency (JAXA)

Seismic waves recorded in the UK Magnitude 6.2, CENTRAL ITALY Wednesday, 24th August, 2016 at 01:36 UTC Seismic waves recorded in the UK P-waves S-waves Surface waves The earthquake occurred at 1:36 UTC in Italy, and the seismic waves from the earthquake reached the UK approximately 4 minutes later. Above you can see seismic waves from the earthquake recorded at seismometers across the UK. The bottom three stations are roughly the same distance from the Earthquake, so the seismic waves arrive at about the same time. The top plot shows that the seismic waves arrive later, and are lower in amplitude at station ESK (shown in blue)

Find out more…. Magnitude 6.2, CENTRAL ITALY Wednesday, 24th August, 2016 at 01:36 UTC Find out more…. University of Liverpool ‘Viewpoint’ article on the earthquake http://news.liv.ac.uk/2015/10/27/viewpoint-deep-thrust-earthquake-in-northern-afghanistan/ BGS (British Geological Survey) – seismology and earthquakes – frequently asked questions http://www.earthquakes.bgs.ac.uk/education/faqs/faq_index.html IRIS (Incorporated Research Institutions for Seismology) – learning about earthquakes http://www.iris.edu/hq/programs/education_and_outreach/students UK School Seismology Project – classroom activities, videos and support documents http://www.bgs.ac.uk/schoolseismology/home.html USGS (United States Geological Survey) – FAQs, glossary, posters, animations http://earthquake.usgs.gov/learn/ USGS summary of the earthquake http://earthquake.usgs.gov/earthquakes/eventpage/us10003re5#general_summary

@seismologyUoL leonrios@liverpool.ac.uk