Edgecumbe New Zealand 1987 (CAR)

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Event ID
198703020142
Event name
Edgecumbe
Country
New Zealand
Region in the country
North Island
World region
Oceania
Epicentral coordinates (long/lat)
POINT(176.92 -30.02)
WKT GIS format
GEMECD contributing partner
CAR
Event narrative

On the afternoon of Monday, March 2, 1987, at 1:42 pm local time, an earthquake of moment magnitude (Mw) 6.5 and focal depth of 8 to 15 km (depending on reporting seismological agency), struck the Bay of Plenty region of New Zealand (northern part of New Zealand’s North Island).

The earthquake was associated to a normal faulting mechanism in active extension in the Taupo volcanic zone, a back arc basin generated by the Hikurangi subduction zone beneath the North Island.

In the Rangitaiki Plains the rupture reached the ground level creating a 7km surface rift that was over one meter wide (Edgecumbe fault); the ground level in proximity of the epicenter dropped up to 2 meters during and immediately after the earthquake.

The epicenter (38.02°S, 176.92°E) was located between the towns of Matata (north-west) and Edgecumbe (south-east).

Numerous foreshocks preceded the main shock, the strongest (ML 4.9) occurred 7 minutes earlier (at 1:35 pm), and probably saved the lives of many people. The main shock was followed in the same day by four aftershocks with magnitude greater than 5.

Date of occurrence (UTC)
1987-03-02
date
Time of occurrence (UTC)
01:42:00
time
Date of occurrence (local)
1987-03-02
date
Time of occurrence (local)
13:42:00
time
Day of the week (local)
Monday
Magnitude
6.5
Magnitude units
Moment (Mw)
Focal depth
15
km
Seismological data: source
USGS
Seismological data: comment

ShakeMap Atlas

Overall impact

Ground shaking in the epicentral region was more vigorous than would have been expected for an event of such magnitude probably due to its shallow focus.The strongest effects were felt in the Rangitaiki Plains and to its margins where almost all the damage was recorded.

Badly hit were the towns of Edgecumbe, Te Teko, Kawerau, Matata and Thornton. Modified Mercalli Intensities (MM) of IX were reported in and around Edgecumbe, with possible instances of MM X.

In the USGS EXPO-CAT database it is estimated that during this earthquake 30,153 people were exposed to intensity VII or higher, of which around 14% were in rural areas.

It is reported that in Kawerau 40 houses were evacuated because of an unstable hill above them, and a higher number of people living in the Te Mahoe town, to the south of Matahina hydro dam was evacuated as precautionary measure.

No one was killed (although unfortunately one person died from a heart attack, possibly caused by the shock of the earthquake) and about 25 people were hospitalized.

The estimated overall economic loss (incl. insured losses and indirect losses) was ˜220 million USD (0.5% of the GDP of New Zealand in that period) and was largely accounted by damage to the commercial and especially industrial facilities in the area (˜80% of the direct economic loss).

The indirect losses represented about 16% of the overall losses, while insured losses accounted for 75%.

The majority of wood frame residences suffered damage to the chimneys or to roof and wall cladding and only few of them had serious structural damage, principally to foundation and rarely to frame.

Communities suffered loss of water, power supplies and sanitary drainage for long periods.

Overview data
Loss: Human Casualty
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People injured
35
number
People injured: source
CAR estimate
People injured: status
Approximate

People seriously injured
25
number
People seriously injured: source
GNS Science and EM-DAT
People seriously injured: comment

One woman was hurt by a falling piano in her home, and another was hit by a bull thrown out of its pen at a stock yard (EQC Rumblings, Issue 19, July 2009). Another was trapped under 11 huge circular saws, each of them 2 metres in diameter.


People missing
0
number

People killed
0
number
People killed: source
GNS Science
People killed: comment

EM-DAT report a death caused by the earthquake (this was due to a heart attack)


People killed due to ground shaking
0
number

People dying post catastrophe due to shaking
1
number
People dying post catastrophe due to shaking: source
http://www.teara.govt.nz/en/historic-earthquakes/page-11
People dying post catastrophe due to shaking: comment

One person died from a heart attack, possibly caused by the shock of the earthquake


People missing due to tsunami
0
number
People killed due to tsunami
0
number
People missing due to fire following
0
number
People killed due to fire following
0
number
People missing due to slope failures
0
number
People killed due to slope failures
0
number
Loss: Building damage
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Total number of buildings destroyed by shaking: status
N/A

Number of buildings damaged by shaking: status
N/A

Number of dwellings destroyed by shaking
11
number
Number of dwellings destroyed by shaking: source
Butcher G., Andrews L., Cleland G., (1998), The Edgecumbe Earthquake. Center for advanced engineering University of Canterbury.

Number of dwellings damaged by shaking
4000
number
Number of dwellings damaged by shaking: source
Butcher G., Andrews L., Cleland G., (1998), The Edgecumbe Earthquake. Center for advanced engineering University of Canterbury.
Number of dwellings damaged by shaking: comment

˜16 out of the 4000 damaged dwellings suffered serious structural damage


Loss: Socioeconomic
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People homeless: status
N/A

Direct economic loss
27.6
million US$
Direct economic loss: source
Butcher G., Andrews L., Cleland G., (1998), The Edgecumbe Earthquake. Center for Advanced Engineering, University of Canterbury.
Direct economic loss: comment

These economic losses relate to 5.2 million US$ for repairs to the lifelines (Table 15); 3.4 million US$ in uninsured losses to houses and police stations; and 19 million US$ for repairs to schools, hospitals, roads, bridges and other public infrastructure (Table 14).

The insured losses (ca 162 million US$) are not included here.


Indirect economic loss
36
million US$
Indirect economic loss: source
Butcher G., Andrews L., Cleland G., (1998), The Edgecumbe Earthquake. Center for Advanced Engineering, University of Canterbury.
Indirect economic loss: comment

Most of the indirect losses (92%) are related to economic effects (business interruption) and the rest is from welfare payments (8%).


Insured loss
162
million US$
Insured loss: source
Butcher G., Andrews L., Cleland G., (1998), The Edgecumbe Earthquake. Center for Advanced Engineering, University of Canterbury.
Insured loss: comment

In New Zealand all residential properties are insured by the Earthquake and War Damage Commission (now known as EQC).

However, the residential damage covered by insurance overstated what could realistically be attributed to the 1987 Edgecumbe earthquake. For example, chimneys were replaced by insurance but for many of them the cause of the damage was not the earthquake.

Butcher et al. (1998) give a detailed breakdown of the insured losses (in Table 14) by line of business as well as to business interruption effects (in Table 12).

Munich Re report much higher losses: 350 million US$ in overall economic losses, of which 270 million US$ in insured losses.


Demographics
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Total number of buildings: status
N/A