FIELD INVESTIGATION ON THE
DAMAGE OF HOUSING AND
INFRASTRUCTURE CAUSED BY
EARTHQUAKE IN CENTRAL JAVA,INDONESIA(Mｗ:6.3; May.27, 2006)

Nippon Koei. Co., Ltd.
T. OHSUMI and K. BABAFIELD INVESTIGATION ON THE DAMAGE OF HOUSING, ROAD AND
INFRASTRUCTURE CAUSED BY EARTHQUAKE IN CENTRAL JAVA,INDONESIA (Mｗ:6.3; May.27, 2006) Nippon Koei. Co., Ltd.

1

Outline
1. Outline of Survey
2. Epicenter and Tectonic
3. Survey Area
4. Views at Candi Prambanan
5. Views at Yogyakarta
6. Views at Bantul
7. Views at Imogiri
8. Views at Gunungkidul
9. Views at Wonogiri Dam
10. Key Issues2

Hypocenter & TectonicHall., R. and Blundell. D., 1996.

The Late Neogene Sunda orogeny affected the segment of the Indonesian arc
between West Java and the islands of Nusa Tenggara as far east as Flores. In
this segment of the arc convergence between the Indian Ocean and SE Asian
plates is normal to the subduction trace in the Java Trench with a rate of c. 7
cm/year. The subduction system comprises an accretionary complex composedof offscraped Indian Ocean floor materials in the Java forearc ridge, aforearcbasin developed on extended continental crust and containing late
Palaeogene to Recent sediments. The volcanic arc which forms the backbone ofJava and formsthe islands to the east is constructed on continental crust in West
Java, on Mesozoic accretionary complexes in Central and east Java and on
oceanic crust in Sumbawa and Flores.
In Central Java the thrust is cut and disrupted by the Cimandari and Citandui
Faults which have wrench components of movement.
Compression may develop when smooth subduction of the down going oceanic
plate is interrupted by topographic irregularities on the seafloor.

Hall., R. and Blundell. D., 1996.

3

An earthquake with a magnitude of 6.3 occurred at 5:54 AM (local time) on May
27, 2006.
The large earthquake attacked the central Java in the early on Saturday caused
5,700 casualties. We carried out damage investigation on housing andinfrastructure, located near the hypocenter, on Java Island. We conducted ourinvestigation from May 5 to 8, 2006.
This figure shows the USGS Shake Map of this earthquake as intensity area.
These results indicate that the strong intensity VI is limited within 50 km.
http://earthquake.usgs.gov/eqcenter/recenteqsww/Quakes/quakes_all.php

4Waveform data obtained by theIndonesian broadband seismographnetwork (Realtime-JISNET)

Source mechanism analysis of the Java earthquake (May 26, 2006) using
waveform data obtained by the Indonesian broadband seismograph network(Realtime-JISNET)
https://relay.nkoei.co.jp/events/YogyaEq_20060526/index2e.html,DanaInfo=www.isn.bosai.go.jp+

NIED estimated the source location and mechanism of this earthquake,using waveform data obtained by the Indonesian broadband seismographnetwork (Realtime-JISNET) operated by Indonesia Meteorological andGeophysical Agency (BMG) and NIED. These results indicate that theepicenter was located approximately 10 km SSE of Yogyakarta City at adepth of 10 km beneath the surface. The moment magnitude (Mw) wasestimated as 6.3.

5

Waveform data

This figure shows three-component waveform data acquired by CMG-3T
EBB (0.02-360 s) at BJI (Banjar Negara) and LEM (Lembang) stations ofRealtime-JISNET. Waveform data were not available for the EWcomponent at BJI due to a trouble of the seismometer in this component.

6According to Dr. Yagi’s inversion, in this earthquake case happened rupture in
two stages.
In first stage as sub-event1, the rupture direction was expanded to a southwest tonortheast and second rupture as sub-event 2 has happened.

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The strike-slip fault which the direction is a southwest to northeast has happened
in depth less than 15km.
The moment release history is complicated and continuation time also amounts
to about 40 seconds.
Even if duration time is assumed at 30 second, it is longer by 2 times than one ofan earthquake of Mw6.5 class.
Moreover, the rupture velocity is rather than slow as about 1.4 km/sec. First, subevent1 occurred 3 seconds, after earthquake and the rupture mainly propagatedto the north and the northeast of the hypocenter. And, sub-event2 occurred
during the 12 seconds after start earthquake. At this time, rupture mainly spread
destruction toward the northeast. Due to directivity effect that the seismic wave is
amplified the areas propagating direction have been damaged heavily.

8KOMPAS, RABU, 31 MEI 2006

9UNOSAT

10UNOSAT

Imogiri (Opak) fault.

This UNOSAT map illustrates a preliminary damage assessment of the mostaffected areas from this earthquake conducted by U.S. movement agencies.
According to this map, the extensive damaged area are located in east-side ofBantul prefecture.
We indicate fault line on this map. As seen in the map, extensive damaged areas
are spreaded in the west-side of Imogiri (Opak) fault.

11Outline of Survey
Date

RouteJune 5 (Tue)JKT-Solo, Candi Prambanan,Janti Fly Over,meeting with Hamengkubuwono X
BPKP, Sermo Dam, Bantul, Imogiri

June 6 (Tue)June 7 (Wed) Jrung Peduck Bridge, Gunungkidul,
June 8 (Thu)

Wonogiri Dam, Solo-JKT

12Survey Member

1. Mr. Koji Baba
(Jakarta Office General Manager, NK)
2. Dr. Tsuneo Ohsumi(Disaster Management, NK)

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QUAKE VICTIM DATA OF YOGYAKARTA SPECIALREGION AS OF 12 JUNE 2006 AT 12:00
Victims
Location

BantulDamage (Residential Houses)

Death

Lightly
Injured

CameHeavily
Down toDamaged
the Ground

Lightly
Damaged

4,141

71,68370,796

Public Facilities
Praying Location

Heavily
Injured

Came
Down

Heavily
DamagedSchoolLightly
Damaged

Came
Down

Heavily
DamagedGovernment Building
LightlyDamaged

Came
Down

Heavily
DamagedLightly
Damaged

8,673

3,353

66,512685

45Sleman

232

690

3,099

5,243

16,00333,233

67

125

90

34

41

Yogya

204

245

73

7,161

14,536

21,192

767

85

Kulon Progo

22

276

2,490

4,527

5,178

8,501

5

108

145

39

57

120

110

11

Gunung Kidul

81

1,086

7,746

10,67027,130

307

1575

38

120

Total

4,680

19,98596,360117,183

156,568438

100

460403302

Lightly
InjuredCame
Heavily
Down toDamaged
the Ground

LightlyDamaged

Victims
CENTRAL JAVA

Death

Heavily
InjuredDamage (Residential Houses)

Public Facilities
Praying Location

Heavily
DamagedLightly
Damaged29,98862,97998,552

76

430

439

Kabupaten Magelang

1024199

507

658

02

1

Kabupaten Boyolali

4300

307

696

708

021

Kabupaten Sukoharjo

367

51

1,808

2,476

6

147

Kabupaten Wonogiri

04171274

25

00

Kabupaten Purworejo

1410214780

000107448

448

30,572

66,216103,248YOGYAKARTA &CENTRAL JAVA

5,743

38,511

126,932

183,399

259,816

Came
Down

Government Building

18,127

18,526

Lightly
DamagedSchool

1,045

1,063

Heavily
Damaged

Heavily
DamagedKabupaten Klaten

Total

Came
Down

Lightly
Damaged

108

438

00

108

100

460

511

Came
Down

1,305

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Candi Prambanan

Prambanan temple caused heavy damage on Ciwa and Garuda temple.Thistemple is located in the 40 km north east of the epicenter.
But this point is located to the end of Imogiri (Opak) fault. It is considered that theseismic wave was amplified by the directivity effect.

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Candi Prambanan

16

Janti Fly Over

Expansion joint of Janti Fly Over unfastened. But this damage is not serious. The fly over isserved for traffic.

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BPKP

parangtritis km 5
BPKP office, which is located at Parangtrits(the ring load southern part of
Yogyakarta from 5 km) is completely damaged in right part by buckling of RC
column and cannot be used any more.

18Sermo Dam

The Sapan dam, which located in 30 km west from the epicenter, the deformationof crest was estimated at 85cm from record of inclinometer after the earthquake.
Final movement is observed at 12 mm. There is no crake in this crest. A
seismograph was installed on the embankment, but this instilment was not out oforder.

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BantulIn BANTUL prefecture, especially at IMOGIRI, housings are totally clapped.

20

BantulResidents live on the tent for fear of aftershock.

21

Bantul

Structure of almost all collapsed houses is brick or reinforced concrete frame andburned brick masonry infill wall with cement mortar.
A roof structure is a tile-roofed on wooden mesh.

22

Imogiri

In IMOGIRI county, this earthquake killed 260 casualties. Among those, at Turi
village killed 22 casualties with a population of 700 person.

23

Patuk

The road-shoulder was collapsed by the earthquake. This point located near theImogiri fault at Patuk.

24

Jrung Peduck Bridge

Jrung Peluk Bridge was collapsed in the left side of abutment, which is locatednear Patuk.

25

Jrung Peduck Bridge

Expansion joint of Jrung Peluk Bridge was collaped at the left side of abutment.

26

Gunungkidul

On the seashore Baron in Gunungkidul, covered in the limestone, the eroded
overhang cliff was collapsed by the earthquake.

27

Wonogiri Dam

The Wonogiri dam is far from the epicenter with 60km, and there is no damage.
As for neighboring people, the false rumor that a crack went into the dam andbecame with panic immediately after the earthquake.

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Summary of field inspection• Damaged areas begin Klaten between
Solo to Yogyakarta.
• The infrastructure have little damage .
• In Bantul, housings are totally clapped.
• Extensive damaged areas are spreaded in
the west‑side of Imogiri fault. 。
• Collapsed houses is brick or reinforced
concrete frame with cement mortar• Dam bodies are also good foundation andno damage.

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Summary of a dislocation and anearthquake• Imogiri fault exist on Opak river.
• The strike‑slip fault which the direction is asouthwest to northeast has happened in depth
less than 15km.
• The length of dislocation is 55 km and thisdislocation spread toward to northeast at Klatenand Tulung.
• In this earthquake case happened rupture in twostages.
• High frequencies were included in waveform as
the seismic source specific character.

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Why did the infrastructure havelittle damage but the housing
have much damage?

Why did the infrastructure have little damage but the housing have muchdamage?
One of the reason is that deformation of foundation was a little as the site specificcharacter on foundation geology and the civil infrastructures were not damaged.
As another reason is that high frequencies were included in waveform as theseismic source specific character and it created large acceleration. As the results,
low flat houses built by brick and Java traditional roof tile structure which is top
heavy structure were broken.

31• One of the reason is that deformation offoundation was a little as the site specificcharacter on foundation geology and the civil
infrastructures were not damaged.
• As another reason is that high frequencies wereincluded in waveform as the seismic source
specific character and it created largeacceleration. As the results, low flat houses built
by brick and Java traditional roof tile structure
which is top heavy structure were broken.

32Why did damaged area
distribute un evenly?

The extensive damaged areas are located in east-side of Bantul prefecture.
Extensive damaged areas are spreaded in the west-side of Imogiri (Opak) fault.
Comparison of west- and east-side of fault, west-side is downthrown and eastside is up thrown.The volcanic lava sediments exist in the west side and tuff andclaystone are laid in the east side. Thus, the west side of the fault, in which
volcanic sediments are not consolidated, was damage seriously.
Moreover, that serious damage in Klaten is considered as follow;
Rupture mainly spread toward the northeast. Due to directivity effect, the seismic
wave is amplified propagating direction and then Klaten area have beendamaged heavily.

Why are the both sides of a fault exist with the damage area region?

33• The extensive damaged areas are located ineast-side of Bantul prefecture. Extensive
damaged areas are spreaded in the west-side of
Imogiri (Opak) fault. Comparison of west- andeast-side of fault, west-side is downthrown andeast-side is up thrown.The volcanic lava
sediments exist in the west side and tuff andclaystone are laid in the east side. Thus, thewest side of the fault, in which volcanic
sediments are not consolidated, was damage
seriously.

34

• Moreover, that serious damage in Klaten
is considered as follow;
Rupture mainly spread toward thenortheast. Due to directivity effect, theseismic wave is amplified propagating
direction and then Klaten area have beendamaged heavily.

35

Key Issues
1) Emergency diagnosis of housings for
public facilities, hospitals, and schools arenecessary to use a great deal of damaged
structures.
2) Effective earthquake resistance method
for a masonry structure needs to bedeveloped.
3)The false rumor that tsunami happened
or a crack went into the dam becamewith panic immediately. after theearthquake.

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Key Issues4) A construction system and anexecution management system need
to be looked again.
5) A water service institution should
be installed and a temporary wellneeds by drilling for ground water.

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