Magnitude 6.3, NORTH OF MOROCCO

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1 Earthquake location & overview A magnitude 6.3 earthquake struck in Alboran Sea, orth of Morocco; the epicentre was centered about 54 km ( 34 miles) E of Al Hoceima. The depth has been estimated to be about 10 km ( 6.2 miles). 100 Miles orth, in Malaga, many people fled their homes as a result of the shaking and it has caused some structural damage to buildings and infrastructure. Fortunately, there have been little to no reports of injuries/fatalities. IDIA Pakistan Tremors are reported to have been felt as far inland as Seville.

2 Tectonic background 20 W 1 0 W E M A P E X P L A A T IO E 5 0 E IDIA L ith u a n ia K a z a k h s ta n B e la ru s Ir e la n d E u r a s i a P l a te U n ite d K in g d o m B e lg iu m F a u lts U k r a in e G e rm a n y C zech R e p u b lic S u b d u c t io n S lo v a k ia T ra n s fo rm D iv e rg e n t A u s t r ia F ra n c e O th e rs R u s s ia IDIA P o la n d e th e rla n d s S w i tz e r l a n d E E a r th q u a k e s M M a g n it u d e The Mediterranean region is seismically active, due to the convergence of African and Eurasian Plates at a rate of about 4-10 mm/. The convergence started from roughly 50 Ma ago and was associated with the closing of the Tethys Sea. 20 E S w eden D e n m a rk S lo v e n ia Ita ly A t la n t i c O c e a n M o ld o v a G e o r g ia H u n g a ry 40 B la c k S e a C r o a t ia B o s n ia & H e r z e g o v in a Ir a n B u lg a r ia A n d o rra Tu rk e y C o rs ic a P o r tu g a l S p a in A lb a n ia S a r d in i a G re e c e 8mm/ B a le a ri c Is l a n d s S y r ia 9 m m /y r 3 0 Magnitude 6.3, orth of Morocco W e s te rn S a h a ra A ra b ia P l a te 9mm/ M e d it e r r a n e a n S e a 10mm 9mm/ / T u n i s i a7mm/ C re te 7 m m /y r M o ro c c o 1 0 m m /y r 9 m m /y r A f r ic a P l a t e A lg e r ia Ir a q C y p ru s L e b a n o n Pakistan C y c la d e s S ic i l y 8 m m /y r Is r a e l J o r d a n 30 Saudi A ra b ia E gyp t L ib y a M a u r it a n i a 0 M a li ,0 0 0 K ilo m e t e r s W E 2 0 E 3 0 E

3 Historical earthquakes In this area, two earthquakes with magnitude greater than 6 occurred in the last 100 years, one with magnitude 6IDIA in 1994 and the other one with magnitude 6.5 in Both earthquakes occurred on near vertical,strike-slip faults (Biggs et al., 2006). Mw 6.3, 2016 Mw 6.0,1994 Pakistan Mw 6.5, 2004

4 Aftershock distribution There are several aftershocks following the main shock until 27th January The largest aftershocks occurred 4.3 km IDIA west and 19.8 km southwest of the main shock respectively, both with magnitude 5.3. Mw 6.3, 2016

5 Rather Strong (V) shaking was felt in some of the coastal Moroccan cities closest to the epicenter. Otherwise Moderate (IV) shaking was felt in the rest of the surrounding region. Shaking Intensity Modified Mercalli Intensity ot felt by many people unless in favourable conditions. I. Scale (MMI) Instrument al 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. oticed 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. Cataclysmi c 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.

6 Green alert for shaking-related fatalities and economic losses. There is a low likelihood of casualties and damage. USGS PAGER Map with MMI contour overlay. Images courtesy of the US Geological Survey.

7 Right: A Pseudo-Spectral Acceleration (PSA) map a period natural period (T) of 1.0 s produced by the USGS. Each contour represents the acceleration of the ground as a percentage of g ( 9.81 ms-2). The most intense shaking at this period was experienced in orthern Morocco at about 2.5% of g. This period corresponds roughly to the natural period of 5 10 story buildings.