1. A magnitude 6.9 earthquake occurred in southern Greece, in the northern Aegean Sea on 24 th May 2014. The earthquake occurred at a shallow depth of 10 km (6.2 miles). The region is tectonically complex and has seen many earthquakes in the past. It is one of Europe’s most tectonically active regions. Early reports suggest that shaking caused by the earthquake resulted in a number of injuries and structural damage to buildings. Magnitude 6.9 earthquake Kamariotissa, Greece Saturday 24 May 2014 at 09:25:03 UTC

2. Modified Mercalli Intensity Scale I. Instrumental Not felt by many people unless in favourable conditions. II. Weak Felt only by a few people at best, especially on the upper floors of buildings. Delicately suspended objects may swing. III. Slight Felt quite noticeably by people indoors, especially on the upper floors of buildings. Many to do not recognise it as an earthquake. Standing motor cars may rock slightly. Vibration similar to the passing of a truck. Duration estimated. IV. Moderate Felt indoors by many people, outdoors by a few people during the day. At night, some awakened. V. Rather Strong Felt outside by most, may not be felt by some people in non-favourable conditions. Dishes and windows may break and large bells will ring. Vibrations like train passing close to house. VI. Strong Felt by all; many frightened and run outdoors, walk unsteadily. Windows, dishes, glassware broken; books fall off shelves; some heavy furniture moved or overturned; a few instances of fallen plaster. Damage slight. VII. Very Strong Difficult to stand; furniture broken; damage negligible in building of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken. Noticed by people driving motor cars. VIII. Destructive Damage slight in specially designed structures; considerable in ordinary substantial buildings with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture moved. IX. Violent General panic; damage considerable in poorly designed structures, well designed frame structures thrown out of plumb. Damage great in substantial buildings, with partial collapse. Buildings shifted off foundations. X. Intense Some well build wooden structures destroyed; most masonry and frame structures destroyed with foundation. Rails bent. XI. Extreme Few, if any masonry structures remain standing. Bridges destroyed. Rails bent greatly. XII. Cataclysmic Total destruction – everything is destroyed. Lines of sight and level distorted. Objects thrown into the air. The ground moves in waves or ripples. Large amounts of rock move position. Landscape altered, or leveled by several meters. In some cases, even the routes of rivers are changed. Distribution of shaking reports (image from EMSC) Where was the earthquake felt? Most significant shaking was felt within a 300 km radius of the earthquakes’ epicentre. The strongest recorded felt intensity VI (strong shaking).The earthquake was felt nearby countries including Turkey (including Istanbul), Greece, Bulgaria, Romania, (including Bucharest), Serbia, Albania. Magnitude 6.9 earthquake Kamariotissa, Greece Saturday 24 May 2014 at 09:25:03 UTC

3. Moderate-sized, shallow earthquakes in this part of the Aegean Sea are not unusual. The 24 th May 2014 earthquake, however, is the largest to have occurred in this region since records began in 1970. Prior to May 2014, the largest recorded events were two M6.7 earthquakes in 1975 and 1983. Historic seismicity (since 1970) showing magnitudes of greater than 5 in the region. The earthquake epicentre is indicated by the red circle. Earthquake locations from the USGS catalogue. Past earthquakes in the region Magnitude 6.9 earthquake Kamariotissa, Greece Saturday 24 May 2014 at 09:25:03 UTC

4. The Eastern Mediterranean region is seismically active due to the northward convergence (4-10 mm/yr) of the African plate with respect to the Eurasian plate along a complex plate boundary. The Northern Anatolian Fault (NAF) is a major fault line caused by the collision of the Arabian plate and the westward escape of Anatolia (Turkey). The NAF separates the Anatolian/Aegean plates and the Eurasian plate and results from the westward escape of Turkey resulting from the collision of the Arabian continent. The 24/05/14 earthquake likely occurred along a westernmost strand of the Northern Anatolian Fault. This is consistent with right-lateral strike-slip faulting along the west-east trending fault plane as shown by the earthquake’s focal mechanism. What caused this earthquake to occur? Magnitude 6.9 earthquake Kamariotissa, Greece Saturday 24 May 2014 at 09:25:03 UTC Tectonic setting of the Eastern Mediterranean region USGS focal mechanism of the earthquake. Arrows show the most likely sense of faulting along the west-east trending fault plane. Schematic illustration of right-lateral strike-slip faulting

5. So far, over 70 aftershocks have been recorded by the EMSC. Most of these have been small (M < 4), but the largest aftershock was a magnitude 5.0 earthquake that occurred just six minutes after the mainshock. Most aftershocks have so far occurred to the east of the mainshock epicentre. More moderate aftershocks can be expected. Aftershocks Magnitude 6.9 earthquake Kamariotissa, Greece Saturday 24 May 2014 at 09:25:03 UTC Map of aftershocks recorded (red circles). The mainshock location is indicated by the red star.

6. Recordings of the earthquake from the British Geological Survey seismometer network Magnitude 6.9 earthquake Kamariotissa, Greece Saturday 24 May 2014 at 09:25:03 UTC

7. USGS webpage for this earthquakes http://earthquake.usgs.gov/earthquakes/eventpage/usb000r2hc#summary http://earthquake.usgs.gov/earthquakes/eventpage/usb000r2hc#summary EMSC webpage for this earthquake: http://www.emsc- csem.org/Earthquake/earthquake.php?id=379935http://www.emsc- csem.org/Earthquake/earthquake.php?id=379935 BGS (British Geological Survey) – seismology and earthquakes – frequently asked questions http://www.earthquakes.bgs.ac.uk/education/faqs/faq_index.html 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 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 http://www.bgs.ac.uk/schoolseismology/home.html USGS (United States Geological Survey) – FAQs, glossary, posters, animations http://earthquake.usgs.gov/learn/ http://earthquake.usgs.gov/learn/ EMSC (European Mediterranean Seismological Centre) http://www.emsc-csem.org/ http://www.emsc-csem.org/ Find out more … Magnitude 6.9 earthquake Kamariotissa, Greece Saturday 24 May 2014 at 09:25:03 UTC