Terceira Island Portugal 1980 (CAR)

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Event ID
198001011642
Event name
Terceira Island
Country
Portugal
Epicentral coordinates (long/lat)
POINT(-27.75 38.73)
WKT GIS format
GEMECD contributing partner
CAR
Event narrative

On New Year’s Day, Tuesday 1st January 1980, at 15:42 local time, an earthquake of moment magnitude 6.9 and focal depth of 12 km struck the volcanic islands of the Azores in the middle of the Atlantic Ocean.

The islands of the Azores are located in a tectonically and volcanically active region straddling the mid-Atlantic ridge and are exposed to geological hazards incl. earthquakes, volcanic eruptions and landslides.

The main shock’s epicentre (38.73°N, 27.75°W) was in the sea between the Terceira, São Jorge and Graciosa Islands roughly 25-35 km from the nearest coasts.

In the USGS EXPO-CAT database it is estimated that during this earthquake 34,000 people were exposed to intensity VII or higher, of which around 45% were in rural areas. Maximum intensities of VIII (with pockets of VIII+) on the Modified Mercalli intensity scale were observed in the southwestern tip of Terceira and the southeastern tip of S. Jorge, while Graciosa’s southwestern tip experienced intensity VII.

Most of the buildings on these islands were one to three storeyed unreinforced stone masonry with wooden floors and roofs covered with clay tiles.

Date of occurrence (UTC)
1980-01-01
date
Time of occurrence (UTC)
16:42:00
time
Date of occurrence (local)
1980-01-01
date
Time of occurrence (local)
15:42:00
time
Day of the week (local)
Tuesday
was it a holiday
Yes
boolean
Magnitude
6.9
Magnitude units
Moment (Mw)
Focal depth
12.2
km
Seismological data: source
USGS
Seismological data: comment

ShakeMap Atlas

Overall impact

Damage was quite significant as 20% of the buildings in the three islands were destroyed and 38% damaged, with Terceira Island losing 25% of its buildings.

The town of Angra do Heroismo (population 12,500), the oldest settlement in the Azores archipelago, was severely affected with 39% of its buildings destroyed particularly in the old town centre (declared by Unesco a World Heritage site in 1983).

Even higher loss ratios occurred on the western coast of Terceira, most extremely affected being the village of Doze Ribeiras where only a handful of its circa 350 buildings was not destroyed. The eastern part of Terceira had lighter damage, although São Sebastião village was seriously damaged. In S. Jorge Island, worst affected were the villages of Topo and Santo Antão.

On the north coast of the island of São Jorge the inhabitants of Fajã da Caldeira de Santo Cristo village, due to landslides, were totally isolated for three days. After several unsuccessful attempts to escape by sea they were evacuated by Portuguese Air Force helicopters.

In total 61 people were killed (56 in Terceira) and around 450 injured (of which 90 required admission to hospital), 5455 buildings were destroyed and 21,500 people became homeless. Churches and other large historic buildings were also badly affected.

The cost of the earthquake was estimated in September 1980 at 410 million US$ (circa 2% of Portugal’s GDP in 1980) by the Office of Support and Reconstruction (GAR).

Overview data
Loss: Human Casualty
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People injured
400
number
People injured: source
http://web.archive.org/web/20080601164106/http://earthquake.usgs.gov/learning/today/his_01_01.php
People injured: status
Greater than

People seriously injured
90
number
People seriously injured: source
Carvahlo, E. (1980). Seismic Rehabilitation in Portugal. Recent Experience and present trends.

People killed
60
number
People killed: source
Carvalho, E.C. (1980). Engineering aspects of the January 1st, 1980 Azores earthquake. 7th World Conference on Earthquake Engineering 9, 477-489.

People killed due to ground shaking
60
number
People killed due to ground shaking: source
Carvalho, E.C. (1980). Engineering aspects of the January 1st, 1980 Azores earthquake. 7th World Conference on Earthquake Engineering 9, 477-489.

Loss: Building damage
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Total number of buildings destroyed by shaking
5455
number
Total number of buildings destroyed by shaking: source
Lucas, A., Oliviera, C. and Guedes, H. (1992). Quantificacao dos danos observados no parque habitacional e do processo da reconstrucao. Monografia. 10 anos apos o sismo dos Acores de 1 de Janeiro de 1980. Secr. Reg. Habit. Obr. Publ., vol.2, 667-742.
Total number of buildings destroyed by shaking: comment

in Terceira, Sao Jorge and Graciosa islands


Number of buildings damaged by shaking
9983
number
Number of buildings damaged by shaking: source
Lucas, A., Oliviera, C. and Guedes, H. (1992). Quantificacao dos danos observados no parque habitacional e do processo da reconstrucao. Monografia. 10 anos apos o sismo dos Acores de 1 de Janeiro de 1980. Secr. Reg. Habit. Obr. Publ., vol.2, 667-742.
Number of buildings damaged by shaking: comment

damaged buildings in Terceira, Sao Jorge and Graciosa islands (excluding the destroyed ones)


Number of dwellings destroyed by shaking: status
N/A

Number of dwellings damaged by shaking: status
N/A

Loss: Socioeconomic
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People homeless
22000
number
People homeless: source
Carvalho, E.C. (1980). Engineering aspects of the January 1st, 1980 Azores earthquake. 7th World Conference on Earthquake Engineering 9, 477-489.
People homeless: comment

in Terceira, Sao Jorge and Graciosa islands

People homeless: status
Approximate

Direct economic loss
410
million US$
Direct economic loss: source
Carvahlo, E. (1980). Seismic Rehabilitation in Portugal. Recent Experience and present trends.
Direct economic loss: comment

Munich Re reports 40 million US$ overall direct economic loss.

Direct economic loss: status
Approximate

Indirect economic loss: status
N/A

Insured loss
0
million US$
Insured loss: source
Munich Re

Demographics
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Total number of buildings: status
N/A