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Institute of Geodynamics, National Observatory of Athens
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- PublicationRestrictedOn the Mw 6.4 SW-Achaia (western Greece) earthquake sequence of 8 June 2008: Seismological, field, GPS observations and stress modeling(2008-12-15T21:56:02Z)
; ; ; ; ; ; ; ;Ganas, A.; Institute of Geodynamics, National Observatory of Athens ;Serpelloni, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Drakatos, G.; Institute of Geodynamics, National Observatory of Athens ;Kolligri, M.; Institute of Geodynamics, National Observatory of Athens ;Adamis, I.; Institute of Geodynamics, National Observatory of Athens ;Tsimi, Ch.; Institute of Geodynamics, National Observatory of Athen ;Batsi, E.; ; ; ; ; ; On 8 June 2008 an Mw(NOA)=6.4 earthquake occurred in NW Peloponnesus, western Greece. This event is the largest strike-slip earthquake to occur in western Greece during the past 25 years. The hypocentre was determined at 18 km depth beneath village Mihoi in SW Achaia. No surface rupture was observed. Many rock falls, slides and liquefaction features have been found as is typical for an earthquake of this size. Double-difference relocations of 370 aftershocks show a linear pattern of events and define a clear NE-SW striking mainshock fault plane. The aftershock region extends approximately 30 km in length, and the width of the surface projection of the aftershocks is as large as 10 km. The depth of the aftershocks rarely exceeds 22 km. Analysis of high-rate GPS data showed that station RLS (Riolos) which is located 12.8 km N5°W of the epicentre was displaced co-seismically 7 mm to the North in agreement with right-lateral kinematics of the rupture. Static (Coulomb) stress transfer analysis indicates loading of faults near the towns of Patras (north) and Amaliada (south), respectively. The earthquake put more emphasis on the role of strike-slip fault in the deformation of western Greece also indicating that seismic strain is partitioned between strike-slip and normal-slip events due to obliquity of the Nubia (Africa) subduction and the N-S extension of the overriding Aegean upper plate156 40 - PublicationRestrictedMonthly migration of a tectonic seismic swarm detected by DInSAR: southwest Peloponnese, Greece(2013)
; ; ; ; ; ; ; ;Kyriakopoulos, C.; Georgia Institute of Technology ;Chini, M.; Luxembourg Institute of Science and Technology ;Bignami, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Stramondo, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Ganas, A.; National Observatory of Athens, ;Kolligri, M.; National Observatory of Athens, ;Moshou, A.; National Observatory of Athens,; ;; ; ; ; In the period 2011 June–October, a tectonic swarm of nearly 1222 earthquakes occurred in the Messenia prefecture at the southwestern region of the Peloponnese Peninsula. The swarm happened in the Messenia’s Upper Quaternary basin, 25 km NW of the city of Kalamata, and migrated from NNW towards SSE. The largest earthquakes occurred in 2011 August 14 (Mw = 4.8), September 14 (Mw = 4.6) and October 10 (Mw = 4.7), caused moderate structural damages mainly in old houses in four villages and produced particular unrest to the local population. We have investigated the monthly migration of the swarm using Differential Synthetic Aperture Radar Interferometry (DInSAR), presenting for the first time a very close look at the deformation evolution that may reveal an aseismic slip component of the total movement. The geodetically derived slip distribution for the first 4 months revealed that slip migrated laterally along strike (north to south) and vertically from a deep portion, at ∼2.8 km depth, to a shallow portion, at less than 0.5 km, of the fault plane, and concluded its migration towards the surface with a very shallow Mw 4.7 event of 2011 October 10 surprisingly detected by DInSAR.233 49 - PublicationRestrictedThe Mw 6.4 SW-Achaia (western Greece) earthquake sequence of 8 June 2008: Seismological, field, GPS observations and stress modeling(2009-10-20)
; ; ; ; ; ; ; ;Ganas, A.; Institute of Geodynamics, National Observatory of Athens, Athens, Greece ;Serpelloni, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Drakatos, G.; Institute of Geodynamics, National Observatory of Athens ;Kolligri, M.; Institute of Geodynamics, National Observatory of Athens ;Adamis, I.; Institute of Geodynamics, National Observatory of Athens ;Tsimi, Ch.; Institute of Geodynamics, National Observatory of Athen ;Batsi, E.; Institute of Geodynamics, National Observatory of Athen; ; ; ; ; ; On June 8, 2008 a Mw = 6.4 earthquake occurred in NW Peloponnese, western Greece. This event is the largest strike-slip earthquake to occur in western Greece during the past 25 years. No surface rupture was observed. Many rock falls, slides, and liquefaction features have been found as is typical for an earthquake of this size. Double-difference relocations of 370 aftershocks show a linear pattern of events and define a clear NE-SW striking mainshock fault plane. The hypocentrer was determined at 18 km depth beneath village Mihoi in SW Achaia. The 24-hr aftershock region extends approximately 30 km in length, and the width of the surface projection of the aftershocks ranges between 5–10 km. The depth of the aftershocks rarely exceeds 22 km. Analysis of high-rate GPS data showed that station RLS (Riolos) which is located 12.8 km N5 W of the epicenter was displaced co-seismically 7 mm to the North in agreement with right-lateral kinematics of the rupture. Static (Coulomb) stress transfer analysis indicates loading of faults near the towns of Patras (north) and Amaliada (south), respectively. The earthquake put more emphasis on the role of strike-slip in the deformation of western Greece also indicating that seismic strain is partitioned between strike-slip and normal-slip events due to obliquity of the Nubia (Africa) – Eurasia convergence.166 25