1986 Kalamata earthquake

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1986 Kalamata earthquake
1986 Kalamata earthquake is located in Greece
1986 Kalamata earthquake
UTC time1986-09-13 17:24:31
ISC event486403
USGS-ANSSComCat
Local date13 September 1986 (1986-09-13)
Local time20:24 EET
Magnitude6.0 Mw[1]
6.2 Ms [2]
Depth11.2 km (7.0 mi)
Epicenter37°00′50″N 22°10′34″E / 37.014°N 22.176°E / 37.014; 22.176Coordinates: 37°00′50″N 22°10′34″E / 37.014°N 22.176°E / 37.014; 22.176
TypeNormal
Areas affectedGreece
Max. intensityX (Extreme)[3]
TsunamiNone
Casualties20–22 dead, 300 injured

The 1986 Kalamata earthquake struck the southern Peloponnese Region of Greece on September 13 at 20:24 local time. The moment magnitude 6.0 or surface wave magnitude 6.2 earthquake had an epicenter located near the coastal city of Kalamata.[1][2] It was assigned X (Extreme) on the Modified Mercalli intensity scale, resulting in localized extensive damage.[3] At least 20 people were killed and approximately 300 injured by the earthquake.

Tectonic setting[]

Greece is a seismically active country, located in a complex zone of interaction of the African, Eurasian, Aegean Sea, and Anatolian plates. Southern Greece itself is located on the Aegean Sea Plate. The Anatolian Plate is moving southwest into the Aegean Sea Plate at a rate of 3 cm per year relative to the Eurasian Plate. Meanwhile, the African Plate undergoes a process known as subduction beneath the Aegean Sea Plate at a rate of 4 cm per year along the Hellenic Subduction Zone.[4]

The city of Kalamata is located at the borders of the valley of Messinia and the Messenian Gulf, which forms a graben feature. To the east are the Taygetus mountain range, which is separated from the graben by a series of normal dip-slip faults, which are part of the seismic zone of Western Mani. One of them is the Kalamata Fault, which runs in a northwesterly direction. This region of Southern Greece is no stranger to earthquakes and their associated tsunamis, including the 1867 earthquake that caused a tsunami and the 1947 earthquake.[5]

Earthquake[]

According to the National Observatory of Athens, the earthquake registered ML 5.5 on the Richter scale. It measured much higher on the surface wave and moment magnitude scales at Ms  6.2 and Mw  6.0 respectively.

Characteristics[]

An analysis of the earthquake focal mechanism corresponds to shallow normal faulting at a shallow depth of 8 km to 11.2 km.[6] The rupture zone of the event was determined to be on a 15 km-long by 10-km-wide fault known as the Kalamata Fault, based on inferring the distribution of aftershocks.[7] Small but notable normal fault scarps and surface ruptures were observed for a total length of 6 km. Some surface ruptures measured up to 6 to 18 cm in veritcal height, and were as wide as 2 to 6 cm.

Aftershocks[]

More than 700 aftershocks were recorded in the first two weeks after the mainshock. The aftershocks were located in two distinct clusters, one north and one south, separated by a gap. The aftershocks focal depths were up to 10 km deep. The southern sequence initiated right after the mainshock at the southern extension of the fault, releasing strain that still remained after the mainshock. The northern aftershock swarm was more active and located further from the surface ruptures, between the Kalamata Fault and the Thuria Fault.[6]

On the 15th of September, a mb  4.9 aftershock occurred south of the mainshock with a Mercalli intensity of VI (Strong), causing 37 injuries and further damaging the Kalamata area.[8]

Impact[]

Damage sustained by the Metropolitan Church of Ypapantis after the earthquake and its subsequent aftershocks.
A USGS ShakeMap of the earthquake.

The high intensity brought by the earthquake resulted in very heavy structural damage. Initial reports said that 112 homes constructed of stone were destroyed and a further 1,100 were damaged.[9] In Kalamata, where shaking intensitywas reported at VIII (Severe), the earthquake razed four buildings to the ground. At least 20% of all structures in the city were so badly damaged that they were unsafe for use, and were demolished. A further 16% of buildings suffered more serious damage, and in the other 36%, damage was moderate.[10] The western part of Kalamata, despite being close to the epicenter, suffered less severe damage.

The effects of the quake on other types of man-made structures, such as bridges and industrial facilities, however, suffered very little damage, or were pratically unaffected. The only structural damage was at the jetty at Kalamata, where cracks up to 10 cm wide were reported. In some locations, the jetty walls partially detached. The quake also caused power outages and disrupted communication services in the city.[2]

The Metropolitan church of Ypapanti suffered severe damage as a result of the earthquake, and had to be restored. It was the second time the church had been damaged by an earthquake, the previous one during the 1886 Peloponnese earthquake.[11] Another church, the Church of Agioi Apostoloi experienced a partial collapse in the quake when its dome and roof fell. It was the first time the church had sustained earthquake damage since 1884.[12] The collapse of the defensive towers of the Holy Monastery of Velanidia (gr) claimed the lives of three individuals.[13]

At Elaiochori, located 7 km from Kalamata, the quake destroyed at least 70% of the buildings. Only 120 buildings were left intact by the end of the quake. The town suffered tremendous damage because it was located in the meizoseismal area, where maximum intensity X (Extreme) was assigned on the Mercalli intensity scale.[14] There were also additional reports of extreme damage in the villages Verga, Poliani, Aris, Artemisia and Nedousa.[2]

Some rockfalls were reported in the Taygetus mountains, and some blocked a major road that linked Kalamata to the town of Sparta, Laconia.[10][15]

Total damage caused by the earthquake has been estimated to be €670,000,000 Euros.[16]

Casualties[]

The quake killed at least 20 people. Of those, six bodies were recovered from a five story reinforced concrete apartment tower that collapsed in the mainshock. Another 15 people were rescued from the same apartment structure after many hours of efforts. Four people died when an old stone building collapsed in . Six people were killed by falling roadside debris. Of the six, one person was crushed by a roof, one by a heart attack, one infant by suffocation and one person by severe injuries. In addition, 330 people were injured, 83 of them has injuries so serious that immediate medical attention was required.[2]

Despite the severity of damage however, the death toll was low because most residents were attending a ferry line opening ceremony when the earthquake occurred.[9]

See also[]

References[]

  1. ^ a b "M 6.0 - 1 km ENE of Paralía Vérgas, Greece". earthquake.usgs.gov. USGS. Retrieved 3 July 2021.
  2. ^ a b c d e S. A. Anagnostopolous; D. Rinaldis; V. A. Lekidis; V. N. Margaris; N. P. Theodulidis (1987). "The Kalamata, Greece, Earthquake of September 13, 1986". Earthquake Spectra. 3 (2): 365–402. doi:10.1193/1.1585434. Retrieved 3 July 2021.
  3. ^ a b "Event 486403 Southern Greece". ISC Bulletin: event catalogue search. International Seismological Centre. doi:10.31905/D808B830. Retrieved 3 July 2021.
  4. ^ Matthew W. Herman; Gavin P. Hayes; Gregory M. Smoczyk; Rebecca Turner; Bethan Turner; Jennifer Jenkins; Sian Davies; Amy Parker; Allison Sinclair; Harley M. Benz; Kevin P. Furlong; Antonio Villaseñor. "Seismicity of the Earth 1900‒2013 Mediterranean Sea and vicinity" (Open-File Report 2010-1083-Q). earthquake.usgs.gov. USGS. doi:10.3133/ofr20101083Q. Retrieved 11 August 2021.
  5. ^ S. Stiros; V. Kontogianni (2008). "Modelling of the 1986 Kalamata (SW Greece) earthquake faulting using geodetic data". Journal of Applied Geodesy. De Gruyter. 2 (3). doi:10.1515/JAG.2008.020.
  6. ^ a b H. Lyon-Caen, R. Armijo, J. Drakopoulos, J. Baskoutass, N. Delibassis, R. Gaulon, V. Kouskouna, J. Latoussakis, K. Makropoulos, P. Papadimitriou, D. Papanastassiou, G. Pedotti (1988). "The 1986 Kalamata (South Peloponnesus) Earthquake: Detailed study of a normal fault, evidences for east-west extension in the Hellenic Arc". 93 (B12): 14967–15000. doi:10.1029/JB093iB12p14967. Retrieved 3 July 2021. Cite journal requires |journal= (help)CS1 maint: multiple names: authors list (link)
  7. ^ Jean-Christophe Gariel; Pierre-Yves Bard; Kyriazis Pitilakis (1991). "A theoretical investigation of source, path and site effects during the 1986 Kalamata earthquake (Greece)". Geophysical Journal International. 104 (1): 165–177. doi:10.1111/j.1365-246X.1991.tb02502.x.
  8. ^ "M 4.9 - 6 km NW of Kardamýli, Greece". earthquake.usgs.gov. USGS. Retrieved 3 July 2021.
  9. ^ a b Hope, Kerin (14 September 1986). "Death Toll Rises in Kalamata Earthquake". Kalamata, Greece: Associated Press. Retrieved 3 July 2021.
  10. ^ a b "Καλαμάτα 1986 (ΙΧ)". oasp.gr (in Greek). Retrieved 11 August 2021.
  11. ^ "Church of Ypapanti". greece.terrabook.com. TerraBook. Retrieved 11 August 2021.
  12. ^ "Church of Agioi Apostoloi (Church of the Holy Apostles)". Atlas Obscura. Retrieved 11 August 2021.
  13. ^ "Ιερά Μονή Βελανιδιάς - Το ιστορικό αλλά και... πολύπαθο μοναστήρι της Μεσσηνίας (Βίντεο)". travel.eleftheriaonline.gr. 21 May 2018. Retrieved 11 August 2021.
  14. ^ Nikolaos Theofanopoulos; Kazuo Dan (1988). "Simulation of the ground motion at Kalamata City - Greece" (PDF). Proceedings of Ninth World Conference on Earthquake Engineering. Japan. 2.
  15. ^ "Εκδήλωση μνήμης για τα 32 χρόνια από τους σεισμούς του 1986". kalamata.gr (in Greek). 2018. Retrieved 11 August 2021.
  16. ^ Ioannis Kassaras; D. Kazantzidou-Firtinidou; Vasilis Kapetanidis; A Ganas (2018). "Seismic risk and loss assessment for Kalamata (SW Peloponnese, Greece) from neighbouring shallow sources" (PDF). Bollettino di geofisica teorica ed applicata. 59 (1). doi:10.4430/bgta0222.
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