Recent earthquake activity of March 2021 in northern Thessaly unlocks new scepticism on Faults

This short opinion article presents and highlights new and old problems related to active geological faults, as seismic sources, after the experience of the last March 3 and 4, 2021 (Mw6.3 and Mw6.0, respectively) Tyrnavos-Elassona earthquakes in northern Thessaly, Greece. Although the active faults in the area are very well studied, demonstrating typical geomorphic features that intensely affect the morphological relief, it seems that the earthquakes were produced by unknown faults emerging in the mountainous area (alpine basement). Primary (?) coseismic ruptures, however, were also observed northwards along the Titarissios valley. A geological interpretation of the faulting mechanism is also proposed. The existence of a new unknown source in an intermontane area is problematic. The role of inherited alpine structures seems more important today than in the past. The strike of the two new seismogenic sources, responsible for the two strongest events of the 2021 earthquake succession, differs from the previously known active faults. This forces us to reconsider older views on the direction of development of active faults and the orientation of the stress field. Concerns are being raised about how new structures can be detected and their role in seismic hazard assessment, especially when located near or within the urban fabric, in cities that are now constantly expanding and being established in new, often loose soils.

PDF

___

Akinci A, Cheloni D, Dindar AA (2021). The 30 October 2020, M7. 0 Samos Island (Eastern Aegean Sea) Earthquake: effects of source rupture, path and local-site conditions on the observed and simulated ground motions. Bulletin of Earthquake Engineering 1-27. doi: 10.1007/s10518-021-01146-5
Barka AA, Kadinsky-Cade K (1988). Strike-slip fault geometry in Turkey and its influence on earthquake activity. Tectonics 7 (3): 663-84.
Boncio P, Galli P, Naso G, Pizzi A (2012). Zoning surface rupture hazard along normal faults: insight from the 2009 Mw 6.3 L’Aquila, Central Italy, earthquake and other global earthquakes. Bulletin of the Seismological Society of America 102 (3): 918-935.
Braunmiller J, Nabelek J (1996). Geometry of continental normal faults: seismological constraints. Journal of Geophysical Research 10: 3045–3052.
Caputo R, Pavlides S (1993). Late Cainozoic geodynamic evolution of Thessaly and surroundings (central-northern Greece). Tectonophysics 223 (3-4): 339-362.
Caputo R, Bravard JP, Helly B (1994). The Pliocene-quaternary tectosedimentary evolution of the Larissa plain (eastern Thessaly, Greece). Geodinamica Acta 7 (4): 219-231.
Caputo R, Helly B, Pavlides S, Papadopoulos G (2004). Palaeoseismological investigation of the Tyrnavos fault (Thessaly, central Greece). Tectonophysics 394 (1-2): 1-20.
Caputo R, Helly B, Pavlides S, Papadopoulos G (2006). Archaeoand palaeoseismological investigations in Northern Thessaly (Greece): insights for the seismic potential of the region. Natural Hazards 39 (2): 195-212.
Caputo R, Sboras S, Pavlides S, Chatzipetros A (2015). Comparison between single-event effects and cumulative effects for the purpose of seismic hazard assessment. A review from Greece. Earth-Science Reviews 148: 94-120. doi: 10.1016/j. earscirev.2015.05.004
Chatzipetros A, Pavlides S, Sboras S, Galanakis D, Pikridas C et al. (2021). The northern Thessaly strong earthquakes of March 3 and 4, 2021, and their neotectonic setting. Bulletin of the Geological Society of Greece 58: 222-255 doi: 10.12681/ bgsg.27225
Chiarabba C, Selvaggi G (1997). Structural control on fault geometry: example of the Grevena Ms 6.6, normal faulting earthquake. Journal of Geophysical Research: Solid Earth 102 (B10): 22445-22457.
DePolo CM, Clark DG, Slemmons DB, Ramelli AR (1991). Historical surface faulting in the Basin and Range province, western North America: implications for fault segmentation. Journal of Structural Geology 13 (2): 123-136. doi: 10.1016/0191- 8141(91)90061-M
Dimitriou D, Giakoupis P (1998). Mine research of coal deposit in Elassona: Domeniko sub-area. Technical report, Institute of Geological and Mineral Exploration (IGME), Athens (in Greek).
Doutsos T, Koukouvelas I, Zelilidas A, Kontopoulos N (1994). Intracontinental wedging and post-orogenic collapse in the Mesohellenic Trough. Geologische Rundschau 83: 257-275.
Ekström G, England P (1989). Seismic strain rates in regions of distributed continental deformation. Journal of Geophysical Research: Solid Earth 94 (B8): 10231-10257.
Ferrière J, Reynaud JY, Pavlopoulos A, Bonneau M, Migiros G et al. (2004). Geologic evolution and geodynamic controls of the Tertiary intramontane piggyback Meso-Hellenic basin, Greece. Bulletin de la Société géologique de France 175 (4): 361-81.
Ferriere J, Chanier F, Reynaud JY, Pavlopoulos A, Ditbanjong P et al. (2011). Tectonic control of the Meteora conglomeratic formations (Mesohellenic basin, Greece). Bulletin de la Société Géologique de France182 (5): 437-50.
Galanakis D, Sboras S, Konstantopoulou G, Xenakis M (2021). Neogene-Quaternary tectonic regime and macroseismic observations in the Tyrnavos-Elassona broader epicentral area of the March 2021, intense earthquake sequence. Bulletin of the Geological Society of Greece 58: 200-21. doi: 10.12681/ bgsg.27196
Ganas A, Valkaniotis S, Briole P, Serpetsidaki A, Kapetanidis V et al. (2021). Domino-style earthquakes along blind normal faults in Northern Thessaly (Greece): kinematic evidence from field observations, seismology, SAR interferometry and GNSS. Available from: https://www.researchgate.net/ publication/353128595_Domino-style_earthquakes_along_ blind_normal_faults_in_Northern_Thessaly_Greece_ kinematic_evidence_from_field_observations_seismology_ SAR_interferometry_and_GNSS [accessed Oct 09 2021].
Godfriaux I (1970). Etude géologique de la région de l’Olympe (Grèce). Annales Géologiques des Pays Helléniques 19: 1-281
Grützner C, Schneiderwind S, Papanikolaou I, Deligiannakis G, Pallikarakis A, Reicherter K (2016). New constraints on extensional tectonics and seismic hazard in northern Attica, Greece: the case of the Milesi Fault. Geophysical Journal International 204 (1): 180-99. doi: 10.1093/gji/ggv443
Guerrieri L, Blumetti AM, Comerci V, Di Manna P, Michetti AM et al. (2015). Surface Faulting Hazard in Italy: Towards a First Assessment Based on the ITHACA Database. In: Engineering Geology for Society and Territory-Vol. 5: Urban Geology, Sustainable Planning and Landscape Exploitation, Springer, 1021-1025.
Hatzfeld D, Karakostas V, Ziazia M, Selvaggi G, Leborgne S et al. (1997). The Kozani-Grevena (Greece) earthquake of 13 May 1995 revisited from a detailed seismological study. Bulletin of the Seismological Society of America 87 (2): 463-473.
Hatzfeld D, Karakostas V, Ziazia M, Kassaras I, Papadimitriou E et al. (2000). Microseismicity and faulting geometry in the Gulf of Corinth (Greece). Geophysical Journal International 141 (2): 438-456. doi: 10.1046/j.1365-246x.2000.00092.x
IGME – Institute of Geology and Mineral Exploration (1987). Geological Map of Greece, “Elasson” sheet, 1:50.000 scale, IGME, Athens
IGME – Institute of Geology and Mineral Exploration (1998). Geological Map of Greece, “Farkadon” sheet, 1:50.000 scale, IGME, Athens
Jackson JA, Gagnepain J, Houseman G, King GCP, Papadimitriou P et al. (1982). Seismicity, normal faulting, and the geomorphological development of the Gulf of Corinth (Greece): the Corinth earthquakes of February and March 1981. Earth and Planetary Science Letters 57 (2): 377-397.
Karakostas V, Papazachos C, Papadimitriou E, Foumelis M, Kiratzi A et al. (2021). The March 2021 Tyrnavos, central Greece, doublet (Μw6.3 and Mw6.0): Aftershock relocation, faulting details, coseismic slip and deformation. Bulletin of the Geological Society of Greece 58: 131-178. doi: 10.12681/bgsg.2723.
Karasözen E, Nissen E, Büyükakpınar P, Cambaz MD, Kahraman M et al. (2018). The 2017 July 20 M w 6.6 Bodrum–Kos earthquake illuminates active faulting in the Gulf of Gökova, SW Turkey. Geophysical Journal International 214 (1): 85-199.
Kilias A (1995). Tectonic evolution of the Olympus - Ossa mountains : emplacement of the blueschists unit in eastern Thessaly and exhumation of Olympus - Ossa carbonate dome as a resault of tertiary extension (Central Greece). Mineral Wealth 96: 7–22.
Kilias AD, Vamvaka A, Falalakis G, Sfeikos A, Papadimitriou E et al. (2015). The Mesohellenic Trough and the Paleogene Thrace Basin on the Rhodope massif, their structural evolution and geotectonic significance in the Hellenides. Journal of Geology and Geosciences 4 (2): 198. doi: 10.4172/2329-6755.1000198
Kiratzi A, Louvari E (2003). Focal mechanisms of shallow earthquakes in the Aegean Sea and the surrounding lands determined by waveform modelling: a new database. Journal of Geodynamics 36 (1-2): 251-274.
Koukouvelas IK, Nikolakopoulos KG, Kyriou A, Caputo R, Belesis A et al. (2021). The March 2021 Damasi Earthquake Sequence, Central Greece: Reactivation Evidence across the Westward Propagating Tyrnavos Graben. Geosciences 11 (8): 328. doi: 10.3390/geosciences11080328
Lallemant S, Truffert C, Jolivet L, Henry P, Chamot-Rooke N et al. (1994). Spatial transition from compression to extension in the Western Mediterranean Ridge accretionary complex. Tectonophysics 234 (1-2): 33-52.
Le Pichon X, Lallemant SJ, Chamot-Rooke N, Lemeur D, Pascal G (2002). The Mediterranean Ridge backstop and the Hellenic nappes. Marine Geology 186 (1-2): 111-25. doi: 10.1016/ S0025-3227(02)00175-5
Louvari E, Kiratzi A (2001). Source parameters of the September 7, 1999 Athens (Greece) earthquake from teleseismic data. Journal of the Balkan Geophysical Society 43 (3): 51–60. (Available: http://www.balkangeophysoc.org).
Makris J, Papoulia J (2012). Mapping sedimentary basins and crust offshore western and southern Greece by wide aperture reflection/refraction profiling – contribution to hydrocarbon exploration. In: Christophorou L.G. (Ed), Greek hydrocarbons: from exploration to exploitation, Athens Academy, 163-175 (in Greek).
McKenzie D (1972). Active tectonics of the Mediterranean region. Geophysics Journal of the Royal Astronomical Society 30: 109–185.
Özbakır AD, Şengör AM, Wortel MJ, Govers R (2013). The Pliny– Strabo trench region: a large shear zone resulting from slab tearing. Earth and Planetary Science Letters 375: 188-95. doi: 10.1016/j.epsl.2013.05.025
Palyvos N, Pavlopoulos K, Froussou E, Kranis H, Pustovoytov K et al. (2010). Paleoseismological investigation of the obliquenormal Ekkara ground rupture zone accompanying the M 6.7–7.0 earthquake on 30 April 1954 in Thessaly, Greece: Archaeological and geochronological constraints on ground rupture recurrence. Journal of Geophysical Research: Solid Earth 115: B06301. doi: 10.1029/2009JB006374
Papadimitriou P, Voulgaris N, Kassaras I, Kaviris G, Delibasis N et al. (2002). The M w= 6.0, 7 September 1999 Athens earthquake. Natural Hazards 27 (1): 15-33.
Papastamatiou D, Mouyiaris N (1986). The Sophadhes earthquake occurred on April 30th 1954 - field observations by Yannis Papastamatiou. Geol. and Geoph. Res., Sp. Issue, 341-362.
Papazachos BC (1990). Seismicity of the Aegean and surrounding area. Tectonophysics 178 (2-4): 287-308.
Pavlides S (1993). Active faulting in multi-fractured seismogenic areas; examples from Greece, Z. Geomorph N. E. 94: 57-72.
Pavlides SB, Papadopoulos G, Ganas A (2002). The fault that caused the Athens September 1999 Ms= 5.9 earthquake: Field observations. Natural Hazards 27 (1): 61-84.
Pavlides S, Chatzipetros A, Sboras S, Kremastas E, Chatziioannou A (2021). The northern Thessaly strong earthquakes of March 3 and 4 and their neotectonic setting. doi: 10.5281/ ZENODO.4618188
Pondrelli S (2002). European-Mediterranean Regional CentroidMoment Tensors Catalog (RCMT) [Data set]. Istituto Nazionale di Geofisica e Vulcanologia (INGV). doi: 10.13127/ rcmt/euromed
Poulos SE, Lykousis V, Collins MB, Rohling EJ, Pattiaratchi CB (1999). Sedimentation processes in a tectonically active environment: the Kerkyra–Kefalonia submarine valley system (NE Ionian Sea). Marine Geology 160 (1-2): 25-44.
Rigo A, Lyon-Caen H, Armijo R, Deschamps A, Hatzfeld D et al. (1996). A microseismic study in the western part of the Gulf of Corinth (Greece): implications for large-scale normal faulting mechanisms. Geophysics Journal International 126 (3): 663- 688. doi: 10.1111/j.1365-246X.1996.tb04697.x
Sakellariou D, Rousakis G, Vougioukalakis G, Ioakim C, Panagiotopoulos I et al. (2016). Deformation pattern in the western North Aegean trough: preliminary results. Bulletin of the Geological Society of Greece 50 (1): 124-33.
Sboras S, Lazos I, Mouzakiotis E, Karastathis V, Pavlides S et al. (2020). Fault modelling, seismic sequence evolution and stress transfer scenarios for the July 20, 2017 (MW 6.6) Kos–Gökova Gulf earthquake, SE Aegean. Acta Geophysica 68 (5): 1245- 1261.
Sboras S, Lazos I, Bitharis S, Pikridas C, Galanakis D et al. (2021). Source modelling and stress transfer scenarios of the October 30, 2020 Samos earthquake: seismotectonic implications. Turkish Journal of Earth Sciences, Special Issue 30: 699-717.
Şengör AM, Tüysüz O, Imren C, Sakınç M, Eyidoğan H et al. (2005). The North Anatolian fault: A new look. Annual Review of Earth and Planetary Sciences 33: 37-112. doi: 10.1146/annurev. earth.32.101802.120415
Tolomei C, Caputo R, Polcari M, Famiglietti NA, Maggini M et al. (2021). The Use of Interferometric Synthetic Aperture Radar for Isolating the Contribution of Major Shocks: The Case of the March 2021 Thessaly, Greece, Seismic Sequence. Geosciences 11: 191. doi: 10.3390/geosciences11050191
Tsodoulos IM, Stamoulis K, Caputo R, Koukouvelas I, Chatzipetros A et al. (2016). Middle–Late Holocene earthquake history of the Gyrtoni Fault, Central Greece: Insight from optically stimulated luminescence (OSL) dating and paleoseismology. Tectonophysics 687: 14-27.
Vamvaka A, Kilias A, Mountrakis D, Papaoikonomou J (2006). Geometry and structural evolution of the Mesohellenic Trough (Greece): a new approach. Geological Society of London, Special Publications 260 (1): 521-538.
Vannucci G, Gasperini P (2004). The new release of the database of Earthquake Mechanisms of the Mediterranean Area (EMMA Version 2). Annals of Geophysics 47 (1 Sup.).
Voidomatis P (1989). Some aspects of a seismotectonic synthesis in the North Aegean Sea and surrounding area. Bolletino Geofisica Teorica ed Applicata 31: 49-61.
Zelilidis A, Piper DJW, Kontopoulos N (2002). Sedimentation and basin evolution of the Oligocene-Miocene Mesohellenic basin, Greece. AAPG Bulletin 86 (1): 161-182.