1986 Kalamata earthquake
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The 1986 Kalamata earthquake struck the southern Peloponnese Region of Greece on September 13 at 20:24
local time Local time is the time observed in a specific locality. There is no canonical definition. Originally it was mean solar time, but since the introduction of time zones it is generally the time as determined by the time zone in effect, with daylight s ...
. The
deep Deep or The Deep may refer to: Places United States * Deep Creek (Appomattox River tributary), Virginia * Deep Creek (Great Salt Lake), Idaho and Utah * Deep Creek (Mahantango Creek tributary), Pennsylvania * Deep Creek (Mojave River tributary), ...
moment magnitude The moment magnitude scale (MMS; denoted explicitly with or Mw, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. It was defined in a 1979 pape ...
() 5.9 earthquake had an
epicenter The epicenter, epicentre () or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter or focus, the point where an earthquake or an underground explosion originates. Surface damage Before the instrumental pe ...
near the coastal city of
Kalamata Kalamáta ( el, Καλαμάτα ) is the second most populous city of the Peloponnese peninsula, after Patras, in southern Greece and the largest city of the homonymous administrative region. As the capital and chief port of the Messenia regi ...
and was assigned X (''Extreme'') on the Mercalli intensity scale. The earthquake was the result of normal faulting along a northwest-dipping fault and produced surface ruptures. Extensive damage was reported in Kalamata and Elaiochori. At least 20 people died and 330 were injured. Survivors sought refuge at campsites and reconstruction work lasted five years.


Tectonic setting

Greece is a seismically active country located in a complex zone of interaction between the
African Plate The African Plate is a major tectonic plate that includes much of the continent of Africa (except for its easternmost part) and the adjacent oceanic crust to the west and south. It is bounded by the North American Plate and South American Plate ...
the
Aegean Sea The Aegean Sea ; tr, Ege Denizi (Greek: Αιγαίο Πέλαγος: "Egéo Pélagos", Turkish: "Ege Denizi" or "Adalar Denizi") is an elongated embayment of the Mediterranean Sea between Europe and Asia. It is located between the Balkans ...
. Along the
Hellenic arc The Hellenic arc or Aegean arc is an arcuate mountain chain of the southern Aegean Sea located on the southern margin of the Aegean Sea Plate. Geologically it results from the subduction of the African Plate under it along the Hellenic subductio ...
, the African Plate subducts beneath the Aegean Sea at around per year. Shallow-focus earthquakes of less than depth are common—the result of accommodating
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via subduction-related deformation. Back-arc extension occurs within the Aegean Sea, above the subducting crust, causing normal and strike-slip faulting earthquakes. Large intermediate-depth earthquakes occur due to deformation within the subducting plate. The Peloponnese region is characterized by active extensional tectonics which has continued since the
Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Messinia Messenia or Messinia ( ; el, Μεσσηνία ) is a regional unit (''perifereiaki enotita'') in the southwestern part of the Peloponnese region, in Greece. Until the implementation of the Kallikratis plan on 1 January 2011, Messenia was a p ...
and the
Messenian Gulf The Messenian Gulf (, ''Messiniakós Kólpos'') is a sea that is part of the Ionian Sea. The gulf is circumscribed by the southern coasts of Messenia and the southwestern coast of the Mani peninsula in Laconia. Its bounds are Venetiko Islan ...
which forms a graben. To the east is the
Taygetus The Taygetus, Taugetus, Taygetos or Taÿgetus ( el, Ταΰγετος, Taygetos) is a mountain range on the Peloponnese peninsula in Southern Greece. The highest mountain of the range is Mount Taygetus, also known as "Profitis Ilias", or "Prophet ...
mountain range A mountain range or hill range is a series of mountains or hills arranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have arise ...
; separating it from the graben is a series of normal dip-slip faults, which are part of a
seismic zone In seismology, a seismic zone or seismic belt is an area of seismicity potentially sharing a common cause. It may also be a region on a map for which a common areal rate of seismicity is assumed for the purpose of calculating probabilistic ground ...
in
West Mani West Mani ( el, Δυτική Μάνη - ''Dytiki Mani'') is a municipality in the Messenia regional unit, Peloponnese, Greece. The seat of the municipality is the town Kardamyli Kardamili ( el, Καρδαμύλη, variously transliterated as ' ...
. These faults generally trend north–south and accommodates east–west extension. One of them is the Kalamata Fault which strikes north northeast–south southwest and dips northwest at 70–80°. The Kalamata Fault is part of a group of west-dipping faults that separates the Taygetus mountains from the Pamisos river plain. Believed to have formed during the Quaternary, it was not associated with any earthquakes or surface ruptures prior to 1986. The region frequently experience earthquakes and their associated
tsunami A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater exp ...
s and liquefaction such as in
1867 Events January–March * January 1 – The Covington–Cincinnati Suspension Bridge opens between Cincinnati, Ohio, and Covington, Kentucky, in the United States, becoming the longest single-span bridge in the world. It was renamed a ...
and 1947.


Earthquake

The earthquake's focal mechanism corresponded to normal faulting along the Kalamata Fault. The rupture area was determined to be × (length × width) based on inferring its aftershock distribution. The fault ruptured to the surface along its northern extent, causing surface ruptures.


Surface rupture

Small
fault scarp A fault scarp is a small step or offset on the ground surface where one side of a fault has moved vertically with respect to the other. It is the topographic expression of faulting attributed to the displacement of the land surface by movement a ...
s and
surface rupture In seismology, surface rupture (or ground rupture, or ground displacement) is the visible offset of the ground surface when an earthquake rupture along a fault affects the Earth's surface. Surface rupture is opposed by buried rupture, where th ...
s occurred east of Kalamata. These were observed for along a north-northeast–south-southwest trend. Seismologists traced one strand of surface rupture for . Surface ruptures were intermittently accompanied by a
fissure A fissure is a long, narrow crack opening along the surface of Earth. The term is derived from the Latin word , which means 'cleft' or 'crack'. Fissures emerge in Earth's crust, on ice sheets and glaciers, and on volcanoes. Ground fissure ...
. Some surface ruptures measured up to in vertical height and were as wide as . These surface ruptures often appeared in
terraced In agriculture, a terrace is a piece of sloped plane that has been cut into a series of successively receding flat surfaces or platforms, which resemble steps, for the purposes of more effective farming. This type of landscaping is therefore ...
olive grove The olive, botanical name ''Olea europaea'', meaning 'European olive' in Latin, is a species of small tree or shrub in the family Oleaceae, found traditionally in the Mediterranean Basin. When in shrub form, it is known as ''Olea europaea'' 'M ...
s near rocky outcrops. They were several tens of centimeters west of a large fault surface (
slickenside In geology, a slickenside is a smoothly polished surface caused by frictional movement between rocks along a fault. This surface is typically striated with linear features, called slickenlines, in the direction of movement. Geometry of slickensi ...
). A left-lateral offset measuring was observed along the surface rupture northeast of Kalamata. Heavy damage occurred in homes where the surface rupture propagated beneath.


Strong ground motion

Two
accelerograph An accelerograph can be referred to as a strong-motion instrument or seismograph, or simply an earthquake accelerometer. They are usually constructed as a self-contained box, which previously included a paper or film recorder (an analogue instrumen ...
s in Kalamata recorded a maximum
peak ground acceleration Peak ground acceleration (PGA) is equal to the maximum ground acceleration that occurred during earthquake shaking at a location. PGA is equal to the amplitude of the largest absolute acceleration recorded on an accelerogram at a site during a par ...
(pga) of 0.27 ''g'' in the horizontal component. Meanwhile, the pga in the veritcal component was 0.368 ''g''. Pga exceeding 0.1 ''g'' lasted 2.5 seconds while the maximum horizontal velocity was /s. The greater Kalamata and Elaiochori regions were within the meizoseismal area. Downtown Kalamata experienced Modified Mercalli intensity VIII (''Severe''), where damage was heavy; 42 percent of homes were obliterated or had irreparable damage. In Elaiochori and Perivolakia, the Modified Mercalli intensity was X (''Extreme'') and both villages were razed. At Elaiochori, located at an elevation of ,
strong ground motion In seismology, strong ground motion is the strong earthquake shaking that occurs close to (less than about 50 km from) a causative fault. The strength of the shaking involved in strong ground motion usually overwhelms a seismometer, forci ...
was greatly amplified. Seismic waves had short
period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...
s of 0.15–1.6 seconds, affecting short and poorly built structures. Structures in the village, poorly constructed and without retrofitting, were unable to endure the highly amplified shaking.


Aftershocks

Following the mainshock, seismic instruments were installed by the
National Observatory of Athens The National Observatory of Athens (NOA; el, Εθνικό Αστεροσκοπείο Αθηνών) is a research institute in Athens, Greece. Founded in 1842, it is the oldest research foundation in Greece, as it was the first scientific rese ...
,
University of Athens The National and Kapodistrian University of Athens (NKUA; el, Εθνικό και Καποδιστριακό Πανεπιστήμιο Αθηνών, ''Ethnikó ke Kapodistriakó Panepistímio Athinón''), usually referred to simply as the Univers ...
,
Institut de Physique du Globe de Paris The Institut de Physique du Globe de Paris - Université de Paris (IPGP, University of Paris; French for "Paris Institute of Earth Physics") is a French governmental, non-profit research and higher education establishment located in Paris, dedica ...
and Grenoble Observatory. These instruments allowed scientists to determine the focal mechanism and depth of aftershocks. About 740 aftershocks were recorded in the first two weeks after the
mainshock In seismology, the mainshock is the largest earthquake in a sequence, sometimes preceded by one or more foreshocks, and almost always followed by many aftershocks. Foreshock A foreshock is an earthquake that occurs before a larger seismic eve ...
. Most aftershocks had focal mechanisms consistent with the mainshock (normal) while some were dextral strike-slip events on a fault perpendicular to the mainshock source. The largest aftershock on 15 September measured 5.3 and occurred south of the mainshock. It had a maximum intensity of VII (''Very strong''), caused 37 injuries, and further damage in
Kalamata Kalamáta ( el, Καλαμάτα ) is the second most populous city of the Peloponnese peninsula, after Patras, in southern Greece and the largest city of the homonymous administrative region. As the capital and chief port of the Messenia regi ...
. These aftershocks were distributed across a × zone in two distinct clusters; north and south, separated by a zone without any. The gap measured and extended to a depth of . The lack of seismicity in the gap was the result of smooth rupturing along the fault. At depth, the two aftershocks clusters merged. These aftershocks had
focal depth In seismology, the depth of focus or focal depth refers to the depth at which an earthquake occurs. Earthquakes occurring at a depth of less than are classified as shallow-focus earthquakes, while those with a focal depth between and are commonl ...
s up to deep but none originated beyond . The southern sequence initiated immediately following the mainshock at the southern extension of the Kalamata Fault, releasing strain that still remained. The northern aftershock
swarm Swarm behaviour, or swarming, is a collective behaviour exhibited by entities, particularly animals, of similar size which aggregate together, perhaps milling about the same spot or perhaps moving ''en masse'' or migrating in some direction. ...
experienced greater activity.


Impact

Total damage was estimated at
The euro sign () is the currency sign used for the euro, the official currency of the eurozone and unilaterally adopted by Kosovo and Montenegro. The design was presented to the public by the European Commission on 12 December 1996. It consists ...
670 million. In Kalamata, four buildings were razed. Of the 9,124 buildings in the city, at least 20 percent of buildings sustained damage so extreme, they were demolished. A further 16 percent of buildings were heavily damaged, and in the other 36 percent, damage was moderate. The western part of Kalamata, despite its close proximity to the epicenter, was not as severely damaged. Forty four reinforced concrete buildings had to be torn down. An additional 289 mixed and 1,931 load-bearing masonry structures were also demolished. The Metropolitan Church of Ypapanti was heavily damaged and had to be restored. It was the second time the church had been damaged by an earthquake, the previous one occurring in
1886 Events January–March * January 1 – Upper Burma is formally annexed to British Burma, following its conquest in the Third Anglo-Burmese War of November 1885. * January 5– 9 – Robert Louis Stevenson's novella ''Strange ...
. The dome and roof of the Church of Agioi Apostoloi collapsed. The church was previously damaged by an earthquake in 1884. The defensive towers of the Holy Monastery of Velanidia also collapsed. Structures such as bridges and industrial facilities sustained little damage or were unaffected. Cracks up to wide were reported in a
jetty A jetty is a structure that projects from land out into water. A jetty may serve as a breakwater, as a walkway, or both; or, in pairs, as a means of constricting a channel. The term derives from the French word ', "thrown", signifying some ...
at Kalamata. Parts of the jetty walls partially detached.
Power outage A power outage (also called a powercut, a power out, a power failure, a power blackout, a power loss, or a blackout) is the loss of the electrical power network supply to an end user. There are many causes of power failures in an electricity ...
s occurred and communication services were disrupted in Kalamata. Some rockfalls occurred in the
Taygetus The Taygetus, Taugetus, Taygetos or Taÿgetus ( el, Ταΰγετος, Taygetos) is a mountain range on the Peloponnese peninsula in Southern Greece. The highest mountain of the range is Mount Taygetus, also known as "Profitis Ilias", or "Prophet ...
mountains, obstructing a major road that linked Kalamata to
Sparta, Laconia Sparta ( el, Σπάρτη ) is a city and municipality in Laconia, Greece. It lies at the site of ancient Sparta. The municipality was merged with six nearby municipalities in 2011, for a total population (as of 2011) of 35,259, of whom 17,408 l ...
. At Elaiochori, located from Kalamata, at least 70 percent of its buildings were destroyed—only 120 remained intact. The town suffered tremendous damage because it was located in the meizoseismal area. Extreme damage also occurred in the villages of Verga, Poliani, Aris, Artemisia and Nedousa.


Casualties

At least 20 people were killed—despite the severity of damage, the death toll was low because most residents attended a ferry line opening ceremony when the earthquake occurred. Six bodies were recovered from a five-story reinforced concrete apartment tower that collapsed. Six people died from falling roadside debris; one person was crushed, one died from a heart attack, an infant died from suffocation and another from serious injuries. Three individuals perished when the Holy Monastery of Velanidia's defensive towers collapsed. Four people died when an old stone building collapsed in Elaiochori. An additional 330 people were injured—83 in serious condition and immediate medical attention was required.


Aftermath

Rescuers immediately attended to two buildings in Kalamata; a collapsed apartment and another two-storey house where two people were trapped. They were accompanied by members of the
Greek Army The Hellenic Army ( el, Ελληνικός Στρατός, Ellinikós Stratós, sometimes abbreviated as ΕΣ), formed in 1828, is the land force of Greece. The term ''Hellenic'' is the endogenous synonym for ''Greek''. The Hellenic Army is the ...
,
Police The police are a constituted body of persons empowered by a state, with the aim to enforce the law, to ensure the safety, health and possessions of citizens, and to prevent crime and civil disorder. Their lawful powers include arrest and th ...
and
Fire Service A fire department (American English) or fire brigade (Commonwealth English), also known as a fire authority, fire district, fire and rescue, or fire service in some areas, is an organization that provides fire prevention and fire suppression se ...
. Rescuers pulled four survivors from the apartment building immediately. Another seven people were rescued the following afternoon. Rescue efforts were disrupted by curious onlookers, friends and family members of those trapped visiting the site. Rescue teams from
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and
Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...
also assisted. The reconstruction of basic infrastructures continued for five years under strict seismic codes. Many displaced individuals sought refuge across 30 campsites while their homes were reconstructed. Some residents left the city for other areas such as
Athens Athens ( ; el, Αθήνα, Athína ; grc, Ἀθῆναι, Athênai (pl.) ) is both the capital and largest city of Greece. With a population close to four million, it is also the seventh largest city in the European Union. Athens dominates ...
.


See also

* List of earthquakes in 1986 *
List of earthquakes in Greece This list of earthquakes in Greece includes notable earthquakes that have affected Greece during recorded history. This list is currently incomplete, representing only a fraction of the possible events. Tectonic setting Greece is located at the c ...


References


Sources

* *


Further reading

* {{Portal bar, Earth sciences, Greece 1986 earthquakes Earthquakes in Greece 1986 in Greece Kalamata History of Messenia Geography of Messenia 1986 disasters in Greece