SCIENTIFIC CORRESPONDENCE
Effects of M 9 Sumatra earthquake and tsunami of 26 December 2004
The great mega thrust M 9 Sumatra earthquake on 26 December 2004 at 06:28:53 am
IST created the most devastating tsunami
in the known history. The deadly tsunami
waves lashed low-lying towns adjoining
the coastline of eleven countries, including Indonesia, Thailand, Malaysia, India
and Sri Lanka, causing more than 150,000
deaths. Closest Indian landmasses to the
epicentre are Andaman and Nicobar Islands
over a narrow arc of about 800 km in the
Bay of Bengal. The maximum intensity of
shaking (on the MSK scale) along the
AndamanNicobar Islands may be placed
at VII and that along the mainland Indian
coast at V. It resulted in the death of over
10,000 persons in India with over 5600
persons missing. Extensive devastation of
the built environment occurred across the
populated AndamanNicobar Islands and
the coastal states of Andhra Pradesh, Tamil
Nadu and Kerala along the mainland
coastline of India.
This communication is based on a study
organized by IIT Kanpur, in which a total
of 13 investigators, divided into six groups
carried out a reconnaissance investigation
on the Indian Mainland coast and islands of
Andaman and Nicobar during 113 January
2005.
The earthquake occurred along the plate
boundary marked by subduction zone between the Indian plate and the Burmese
micro-plate. The subduction zone is characterized by NNWSSE arcuate trench running parallel to the western side of the
Sumatra and the AndamanNicobar Islands.
As a result of this movement of tectonic
plates, the Andaman and Nicobar Islands
have experienced uplift and subsidence
at different places as seen from the field
evidence. At Port Blair, the sea water
level has risen by about one meter, suggesting a subsidence of the landmass, whereas
in Middle Andaman Islands emergence
of new shallow coral beaches suggests
uplift (Figure 1). The implications of rise
in water level by 1 m with respect to the
land are rather severe: the buildings and
roads at lower elevations and the dry
docks are being flooded during high tide,
making them non-functional and disrupting normal activities even weeks after the
event. In Middle Andaman Islands, at
Baratang an older mud volcano became
active again after the earthquake and also
several new small mud volcanoes erupted
along with large ground deformation
(Figure 2). Damages to buildings and other
structures were primarily due to tsunami
(as against due to ground shaking) on the
mainland India, and in Little Andaman
and other islands south of it (Figure 3);
structural damage in islands north of Little
Andaman was primarily due to ground shaking.
Tsunami created giant waves as high as
1012 m; in several instances, objects
were found on top of the trees after the
tsunami. In the islands of Great Nicobar,
Car Nicobar and Little Andaman, buildings
constructed on the coast were washed
away by the great waves, while those located
on high grounds survived. When a number of rows of buildings existed on the
coast, buildings in the first row from the
sea suffered extensive damage, those in
the rear rows did better due to the shielding provided by the front row. In general,
constructions circular in plan (e.g., circular
water tanks, light house) did better under
the onslaught of tsunamis as the water
could easily flow around such objects. At
Car Nicobar about 100 personnel of air-
force (including the family members) lost
life or are missing. However, the operational
area and the air-strip survived enabling
rescue and relief operations by the air force
after the event.
Due to the ground shaking, the wooden
buildings suffered less damage compared
to the more modern RC frame and concrete block masonry buildings. The latter
sustained extensive damage when the
seismic codes were not complied with.
For instance, the Passenger Terminal Building at the Phoenix Bay in Port Blair was
recently constructed but did not comply
with the seismic codes. This rather expensive building has been irreparably damaged.
A number of houses built by local people
using reinforced concrete but without
proper engineering supervision and seismic
detailing collapsed. A three-storey apartment building in Port Blair on stilt columns,
not complying with the codal requirements, collapsed (Figure 4). Similar damages were also observed in Rangat, and
Mayabandar in northern islands as well.
A number of jetties collapsed or were
severely damaged in a number of islands
Figure 1. a, Up-throw of coral beds and rock strata due to uplift on the western coast of middle
Andaman Island near Flat Island (Photo: Javed Malik). b, Seawater flooded Andaman Trunk
Road at Sipi Ghat area near Port Blair during high tide, suggesting subsidence of the landmass.
(Photo: Goutam Mondal).
Figure 2. Eruption of a mud volcano near Jarawa Creek at Baratang Island in Middle Andaman, 105 km north of Port Blair (Photo: Durgesh C. Rai).
CURRENT SCIENCE, VOL. 88, NO. 3, 10 FEBRUARY 2005
357
SCIENTIFIC CORRESPONDENCE
which severely affected the sea traffic and
hence the relief operations (Figure 5). A
new 268 m long bridge between North
Andaman and Middle Andaman at Austen
Strait had to be closed to even the light
vehicles. The superstructure has moved
on the substructure by a substantial amount
and middle three spans fell off from the
bearing (Figure 6 a). Two of the authors had
visited this region two years back after a
moderate M 6.5 earthquake on 14 September 2002 and in their published report1
had expressed concerns about this very
bridge as follows:
Inadequate seating of bridge deck over
piers and abutments is a serious concern
for its safety during a stronger earthquake in future. The bearings are simple
neoprene pads which are far from satisfactory for a bridge located in seismic
zone V. Bridge deck restrainers are the
minimum that need to be provided to
ensure that the spans are not dislodged
from the piers in future earthquakes.
(available at http: //www.nicee.org/EQ_
Reports/Andaman/Andaman_report.htm).
Further, a number of structures in and
around Diglipur area which were damaged
in the 2002 earthquake were again damaged in this earthquake as well. Many of
these have been apparently retrofitted
without proper consideration of eliminating the underlying structural deficiencies
that render them vulnerable to ground
shaking.
Widespread lateral spreading in Andaman
Islands led to significant damage of pavement and drainage structures of Andaman
Trunk Road (ATR) and other link roads.
Lateral spreading and other liquefactionrelated phenomena were responsible for
extensive damage to residential buildings
and healthcare facilities in the low-lying
areas, especially in the vicinity of water
bodies, at several places in the northern
Andaman Islands. The flexible airstrip at
Diglipur developed on unconsolidated
marshy land developed cracks.
Electric power supply was severely affected: the 20 MW fossil-fuel based power
plant at Bamboo Flat near Port Blair was
flooded by tsunami waves causing extensive damage to electrical and mechanical
equipment requiring several weeks for
restoration. The 5.25 MW Kalpong hydroelectric power plant near Diglipur, North
Andaman Islands, also suffered damage
to its turbines which could be restored
only partially in a weeks time. The collapse
358
Figure 3. RC frame building (MES Inspection Bungalow) now stands in waters at the Military
Residential Colony south of Malacca on the east coast of Car Nicobar Island. (Photo: C. V. R.
Murty).
Figure 4. Collapse of a three-storey reinforced concrete frame building at Port Blair (Photo:
Sudhir K. Jain).
Figure 5. Collapse of the 80 m segment of approach in Great Nicobar Island jetty at Campbell
Bay. This has adversely affected the relief work. (Photo: C. V. R. Murty).
CURRENT SCIENCE, VOL. 88, NO. 3, 10 FEBRUARY 2005
SCIENTIFIC CORRESPONDENCE
a
b
Figure 6. a, Three middle spans of Chengappa Bridge over Austen Strait connecting Middle
Andaman and North Andaman Islands, 230 km north of Port Blair fell off from the bearing due
to ground shaking. (Photo: Durgesh C. Rai). b, Complete loss of spans of the four-span RC
bridge at Melmannakudi due to tsunami. (Photo: Alpa Sheth).
of the transmission tower at Middle Strait
further restricted its power distribution to
North Andaman Islands. Longitudinal cracks
at the crest of its rockfill reservoir dam
were also observed.
On the mainland India, the fishing
community living along the shore suffered
the maximum damage: to its housing, to its
boats and fishing equipment, and in terms
of loss of life. The other major sufferers
were the tourists on some of the beaches.
Most houses along the coast had been nonengineered. In general, quality of construction had a major influence on the level of
damage sustained by the buildings. Buildings with low foundation depth, those with
poor building materials, poor integrity and
poor workmanship were worst sufferers.
Several bridges suffered serious damages.
Superstructure of all four spans of a bridge
at Melmanakuddi came off the substructure and two of the spans were washed
away to large distances (Figure 6 b). A good
connection between the superstructure and
the substructure and the additional provision
of restraining upstands, recommended features for seismic design, would have helped
the bridge. Infrastructure in Nagapattinam,
Tamil Nadu was significantly affected: a
railway line on the shore, telecommunication
tower and control panel room were irreparably damaged. Compound walls up to
300 m inside the shoreline were extensively damaged.
In ports and harbours along the mainland
coast, major disturbance was caused by
vessels parting their ropes and becoming
loose and hitting other vessels and causing damage. Small boats and ships were
tossed astray onto the land by the incoming
wave and thereby damaging them. Some
boats were sunk to the basin due to the
returning giant waves. Breakwaters generally did well, and helped reduce the impact
of waves. Beaches shielded by landmass or
by rocky cliff sustained less damage. Seawater intrusion was less in areas covered
with thick vegetation compared to those
with bare lands. Sand deposits due to tsunami in delta areas have damaged standing
crops and affected fertility of the land.
To conclude the earthquake and tsunami
of 26 December 2004 once again highlighted the vulnerability of civil infrastructure and population inhabiting the
Indian territories which are well known
to have significant seismic hazard. The
lack of adequate preparedness against the
probable ground shaking by way of not
designing the structures for earthquake
resistance, led to failure of many buildings
and structures when they were needed
most for the rescue and relief operation.
Further, the hazard posed by tsunami to
CURRENT SCIENCE, VOL. 88, NO. 3, 10 FEBRUARY 2005
Indian coastal regions which has been
conveniently ignored thus far, should become one of the major considerations while
developing civil infrastructure in these
areas. The repair and rehabilitation of structures should be carried out in a manner
which addresses to remedy the underlying structural deficiencies that determine
their performance in earthquakes.
1. Rai, D. C. and Murty, C. V. R., Reconnaissance Report on North Andaman (Diglipur)
Earthquake of 14 September 2002, Department of Civil Engineering, Indian Institute of Technology Kanpur, Kanpur, 2003,
p. 49. Available at www.nicee.org/EQ_
Reports/Andaman/Andaman_report.htm).
ACKNOWLEDGEMENTS. We acknowledge
the contributions by the team members: Hemant
Kaushik, Goutam Mondal, Suresh Ranjan Dash,
J. S. Sodhi and G. Santosh Kumar of IIT Kanpur; and Pratibha Gandhi of IIT Madras. We are
grateful to numerous officials and colleagues in
the affected area who provided help and support
in carrying out the reconnaissance studies.
Financial support from DST, New Delhi is
gratefully acknowledged.
Received 27 January 2005; revised accepted
29 January 2005
SUDHIR K. JAIN1,*
C. V. R. MURTY1
DURGESH C. RAI1
JAVED N. MALIK1
ALPA SHETH2
ARVIND JAISWAL3
1
Department of Civil Engineering,
Indian Institute of Technology Kanpur,
Kanpur 208 016, India
2
Vakil, Mehta and Sheth Consulting
Engineers,
312 Apeejay House,
130 Mumbai Samachar Marg,
Mumbai 400 023, India
3
EON Designers Consulting Engineers,
35, B Vasavi Colony,
Secunderabad 500 015, India
*For correspondence.
e-mail: skjain@iitk.ac.in
359
