Earthquake
and Tsunami of 28 November 1945 in Southern Pakistan
George
Pararas-Carayannis
(Excerpts
from unpublished report on "Seismo-Dynamics of Compressional
Tectonic Collision - Potential for Tsunamigenesis Along Boundaries
of the Indian, Eurasian and Arabian Plates" (Abstract submitted
to the International Conference HAZARDS 2004, Hyderabad, India,
2-4 Dec. 2004 )
Copyright © 2005.
All Rights Reserved
Introduction
On 28 November 1945,
a great earthquake, off Pakistan's Makran Coast (Balochistan)
generated a destructive tsunami in the Northern Arabian Sea and
the Indian Ocean. More than 4,000 people were killed along the
Makran Coast of Pakistan by both the earthquake and the tsunami.
Also, the tsunami
was responsible for loss of life and great destruction along
the coasts of Iran, Oman and western India (and possibly elsewhere).
Origin Time
and Epicenter
The great earthquake
occurred at 21:56 UTC (03:26 IST), on 28 November 1945. Its epicenter
was at 24.5 N 63.0 E., in the northern Arabian Sea, about 100
km south of Karachi and about 87 kms SSW of Churi (Baluchistan),
Pakistan.
Magnitude
and Earthquake Intensity
The earthquake's Richter
Magnitude (Ms) was 7.8. The Moment Magnitude (Mw) was revaluated
to be 8.0; the quake was recorded by observatories in New Delhi,
Kolkata (Calcutta) and Kodaikanal.
The earthquake's intensity
was high throughout the region. It was strongly felt in Baluchistan
and the Las Bela area of Pakistan. It was reported that in the
western and southern sections of Karachi the strong surface motions
lasted for about 30 seconds. According to eyewitness reports,
people were "thrown out of their beds", doors and windows
rattled, and windowpanes broke. The underwater cable link between
Karachi and Muscat (Oman) was damaged, disrupting communications.
The lighthouse at Cape Moze - 45 miles from Karachi - was also
damaged. The earthquake was strongly felt also at Manora, where
the lighthouse was damaged. It was moderately felt in Panjgaur
and Kanpur.
Other Earthquake
Effects
Reports by S.M. Mathur
and D.N. Wadia (pertaining to the Geology of India) mention that
the earthquake caused the eruption of a mud volcano a few miles
off the Makran Coast of Pakistan. This eruption formed four small
islands. It was reported that a large volume of gas emitted at
one of these islands, sent flames "hundreds of meters"
into the sky.
Such mud volcanoes
are not uncommon in the Sindh region of the Makran coast. Their
presence indicates the existence of high petroleum deposits.
They are known to discharge flammable gases such as methane,
ethane and traces of other hydrocarbons. Thus, the flames that
were observed following the eruption of one of the mud volcanoes
resulted from emitted natural gas, which caught fire after the
earthquake.
Overall Tectonic Setting
The following is a
brief overview of the overall tectonic setting and interactions
that affect the seismotectonics of the Makran subduction zone
in the Northern Arabian Sea.
Approximately 20 million
years ago India was connected to the southeastern tip of Africa.
Forces within the mantle caused the development of a rift in
the crust, thus separating the Indo-Australian tectonic plate
from the continent of Africa. For millions of years, this great
tectonic plate drifted and moved in a north/northeast direction.
Several millions of years later, its leading deep sea-floor edge
begun colliding with the Eurasian tectonic plate and thrusting
upward. Eventually, the continuous continent-continent collision
raised the leading oceanic edge above sea level leading to continuing
orogenesis the process that has created the Himalayan Plateau
and the great Himalayan mountain ranges.
The India tectonic
plate has been drifting and moving in a north/northeast direction,
for millions of years colliding with the Eurasian tectonic plate
and forming the Himalayan Mountains.
(USGS graphic showing the migration of the Indian tectonic plate)
As a result of such
migration and collision with the Eurasian tectonic plate, a diffuse
zone of seismicity and deformation developed in the entire region.
Over additional millions of years, the earth's crust further
broke, deformed and folded, creating fractured microplates, great
faults and subduction zones all with high seismic activity.
Complex, kinematic earth movements along the boundaries of such
active zones have caused numerous destructive earthquakes in
India, Pakistan, Afghanistan, Iran and Tibet.
Earthquake
Activity In Pakistan
Most earthquakes in
Pakistan occur in the north, the northwestern and the western
sections of the country along the boundary of the Indian tectonic
plate with the Iranian and Afghan micro-plates.
The Owen Fault Zone
is a transform fault in the Arabian Sea that is associated with
a tectonic boundary. It extends from the Gulf of Aden in a northeast
direction towards the Makran coast where it enters the Balochistan
region. Then it continues as a land fault known as the Chaman
Fault along Pakistan's western frontier with Afghanistan. It
begins near Kalat, in the northern Makran range, passes near
Quetta and continues to Kabul, Afghanistan. Both the Owen Fault
Zone and the Chaman Fault Zone can generate large destructive
earthquakes. The great Quetta earthquake of 1935 occurred along
the Chaman Fault. Other major thrust zones exist along the Kirthar,
Sulaiman and Salt mountain ranges of Pakistan.
Four other major faults exist
in and around Karachi and other parts of deltaic Indus, and along
the southern coast of Makran. The first of these is the Allah
Bund Fault. It traverses Shahbundar, Jah, Pakistan Steel Mills,
and continues to the eastern parts of Karachi - ending near Cape
Monz. Earthquakes along this particular fault have been responsible
for considerable destruction in the past. A major earthquake
in the 13th century destroyed Bhanbhor. Another major earthquake
in 1896 was responsible for extensive damage in Shahbundar.
The second major fault
near Karachi is an extension of the one that begins near Rann
of the Kutch region of India. The third is the Pubb fault which
ends into the Arabian Sea near the Makran coast. Finally, the
fourth major fault near Karachi is located in the lower Dadu
district, near Surajani.
British Geological
Survey graphic of the seismicity of Southern Asia of the Carlsberg
Midoceanic Ridge and of the southern portion of the Arabian Peninsula
and the Red Sea.
Geology
of the Makran Coastal Region
The coastline of Pakistan
along the Arabian Sea extends for about 1,050 km (650 mi) with
800 km of it belonging to the Balochistan Province and 250 km
to the Sindh Province. The Makran Coastal Range forms a narrow
strip of mountains along about 75 percent of the total coast
length, or about 800 km (500 mi). The steep mountains rise to
an elevation of up to 1,500 m (5,000 ft).
The Makran coast is
rugged and tectonic in origin with uplifted terraces, cliffs
and headlands. The entire coastline is characterized by extreme
sediment accretion (Closs et al., 1969, White and Louden, 1983;
Platt et al., 1985; Minshull et al., 1992, Fruehn et al., 1997).
It is one of largest sediment accretionary wedges on earth, with
up to 7 km of sediments deposited in the Gulf of Oman to the
west and major rivers contributing vast amount of sediment to
the offshore region in the east. The accretionary complex is
more than 900 km long and there is no evidence of very active
volcanism. The complex has an east-west orientation and is bounded
on both sides by large transform faults associated with tectonic
plate boundaries.
The Balochistan section of the
Makran coast of Pakistan has several small river deltas. In the
eastern Sindh region of Pakistan the Indus River has formed one
of the largest deltas in the world. Past meandering of Indus
has formed extensive deltas east of Karachi. Extensive sedimentation
from the erosion in the Himalayas has widened the continental
shelf of the Sindh coast to about 150 km. Along the Balochistan
region where there is less sedimentation; the continental shelf
measures only 15-40 km.
NASA Satellite
photo of a section of the Makran rugged and tectonic coastline
showing uplifted terraces, headlands, sandy beaches, mud flats,
rocky cliffs, bays and deltas. Numerous mud volcanoes are present
along the shores.
The Makran
Subduction Zone
The northward movement
and subduction of the Oman oceanic lithosphere beneath the Iranian
micro-plate at a very shallow angle of subduction of about 20
degrees, has dragged tertiary marine sediments into an accretionary
prism at the southern edge of the Asian continent (White and
Louden, 1983; Platt et al., 1985) - thus forming the Makran
coastal region, a belt of highly folded and densely faulted mountain
ridges which parallel the present shoreline. To the west of the
accretionary prism, continental collision of about 10 mm/yr has
formed the Zagros fold and thrust belt. To the east, the area
comprises of a narrow belt, which truncates against the Chaman
transform fault an extensive system that extends on land
in a north-northeast direction along Pakistan's frontier with
Afghanistan.
Offshore, the active tectonic convergence of the India plate
with the Arabian and Iranian microplates of the Eurasian tectonic
block has created a tectonic plate margin - an active subduction
zone along the boundary of the Arabian plate on the Makran coast.
The tectonic plates there converge at an estimated rate of about
30 to 50 mm/y (Platt et al. 1988). Thus, an east-west trench
has been formed south of Makran and, additionally, a volcanic
arc has emerged. Specifically the underthrusting of the Eurasian
plate by the Arabian plate has resulted in the formation of the
Chagai volcanic arc, which extends into Iran. The Koh-e- Sultan
volcano and other volcanic cones in the Chagai area are side
products of this active subduction (Schoppel, 1977)
The morphology of the region
is further complicated by the extensive sedimentation, which
takes place as a result of erosion of Himalayan mountain ranges
and the numerous rivers flowing into the North Arabian Sea. A
very thick sedimentary column enters the subduction zone (Closs
et al., 1969, White and Louden, 1983), so the trench associated
with the present accretionary front in the offshore region of
Makran has been buried by sediments and does not have much of
a morphological relief as other trenches around the world's oceans.
The region of subduction
along the Makran coast of Pakistan and the Gujarat Region of
India where major earthquakes have occurred - one as recently
as 2001.
Seismotectonics
of the Makran Region
The seismicity of
the Makran region is relatively low compared to the neighboring
regions, which have been devastated regularly by large earthquakes
(Jacob and Quittmeyer, 1979). Although infrequent, large earthquakes
such as the 1945 event do occur from time to time on the eastern
portion of the Makran subduction zone and have generated destructive
tsunamis recently and in the distant geologic past. The great
earthquake of 28 November 1945 is an example of the size earthquakes
this subduction zone can produce. It generated a very destructive
tsunami in the Northern Arabian Sea.
Large earthquakes
in the region appear to be preceded by increasing activity of
smaller events. For example, for ten years prior to the 1945
Makran earthquake, there was a concentration of seismic activity
in the vicinity of its epicenter. Although infrequent, it is
believed that large earthquakes can also occur along the west
region of the Makran subduction zone and can generate destructive
tsunamis.
The
Tsunami of 28 November 1945 along the Makran coast of Pakistan
and in the Northern Arabian Sea
Destructive tsunamis
have been generated from large earthquakes along the subduction
zone off the Makran coast of Pakistan in the past. Although the
historic record is incomplete, it is believed that such tsunamis
were destructive on the coasts of Pakistan, Iran, India and Oman
and possibly had significant effects on islands and other countries
bordering the Indian Ocean. The most significant tsunamigenic
earthquake in recent times was that of 28 November 1945. The
tsunami was responsible for great loss of life and destruction
along the coasts of Pakistan, Iran, India and Oman. The tsunami
run-up heights varied from 1 to 13 m. Unfortunately, the effects
of the tsunami to other countries bordering the Indian Ocean
have not been adequately documented. The information on this
event is still inadequate.
The Makran
coast of Pakistan
Effects
of the Tsunami in Pakistan, India, Iran and Oman
PAKISTAN - Along the Makran coast of Pakistan,
the tsunami reached a maximum run up height of 13 m (40 feet).
Its waves destroyed fishing villages and caused great damage
to port facilities. More than 4,000 people died from the combined
effects of the earthquake and the tsunami, but most deaths were
caused by the tsunami.
The waves completely
destroyed and killed all the people at Khudi, a fishing village
about 30 miles west of Karachi. At Dabo Creek, 12 fishermen were
swept into the sea.
Karachi was struck
by waves of about 6.5 feet in height. According to reports the
first wave was recorded at 5:30am local time, then at 7:00am,
7:15am and finally at 8:15am. The last wave at 8:15 was the largest.
The tsunami arrived from the direction of Clifton and Ghizri.
There was no reported damage to the port and boats in the harbor
of Karachi. However, at Keamari the waves flooded a couple of
compounds along the harbor's oil installations.
There was considerable
destruction and loss of life at the towns of Pasni and Ormara
but no details are available. Many people were washed out to
sea. At Pasni the waves destroyed government buildings rest houses
and postal and telegraph facilities.
INDIA - Tsunami waves as high as 11.0 to 11.5 m struck
the Kutch region of Gujarat, on the west coast of India. There
was extensive destruction and loss of life. Eyewitnesses reported
that the tsunami came in like a fast rising tide.
The tsunami reached
as far south as Mumbai. Bombay Harbor, Versova (Andheri), Haji
Ali (Mahalaxmi), Juhu (Ville Parle) and Danda (Khar). In Mumbai
the height of the tsunami was 2 meters. Fifteen (15) persons
were washed away. According to reports the first wave was observed
at 8:15am (local time) on Salsette Island in Mumbai (3). There
was no report on damage at Bombay Harbor.
Five people died at
Versova (Andheri, Mumbai), and six more at Haji Ali (Mahalaxmi,
Mumbai), Several fishing boats were torn off their moorings at
Danda and Juhu.
IRAN - There was extensive flooding
of the low-lying areas, after the tsunamibut no details are available.
OMAN - There was considerable loss of
life and destruction but no details are available. The tsunami
was recorded at Muscat and Gwadar.
Past historical
tsunamis
Though Southern Asia
is seismically active region, tsunamis along the coastlines of
Pakistan and India have been relatively rare, but not unprecedented.
Destructive earthquakes and tsunamis have occurred in the North
Arabian Sea throughout geologic history and in recent times.
Most of these events have not been adequately documented. On
the western side of India, the earthquakes of 1524 and 1819 in
the Kutch region probably generated destructive tsunamis.
The oldest known tsunami
in the region may have been generated by a large magnitude earthquake,
which occurred in the Indus delta/Kutch region in 326 B.C. It
has been reported in the literature (Lietzin 1974, Murty and
Bapat 1999) that this earthquake generated a tsunami in the Arabian
Sea, which destroyed Alexander the Great's Macedonian fleet on
its journey back to Greece after India's conquest.
Potential
Tsunami Generating Sources Along the Makran Seismic Zone of Southern
Pakistan
Although the Makran
Subduction Zone in the Northern Arabian Sea is an active seismic
zone, large tsunamigenic earthquakes have been relatively rare.
It is quite possible that tsunamis in this region have not properly
reported or documented. A thorough analysis of historical records
may reveal their occurrence. Such past tsunamis could have affected
Southern Pakistan, India, Iran, Oman, the Maldives and other
countries bordering the Indian Ocean.
The Makran region
has the potential for very large earthquakes, which can generate
destructive tsunamis in the future. Recent seismic activity indicates
that a large earthquake is possible in the region west of the
1945 event (Quittmeyer, 1978). Such an earthquake could generate
a destructive tsunami.
A factor that could
contribute to the destructiveness of a tsunami along the Makran
coastline would be the relatively large astronomical tide, which
is about 10-11 feet. A tsunami generated during high tide would
be significantly more destructive. Also, the compacted sediments
in this zone of subduction could contribute to a greater tsunami.
A bookshelf type of failure within the compacted sediments
as that associated with the 1992 Nicaragua earthquake could
generate a more destructive tsunami. The significance of the
astronomical tide and of the thick sedimentary layers to tsunami
generation to the tsunami vulnerability of the region, will be
discussed further in another paper.
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AND SECONDARY REFERENCES
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LINKS TO PAST
AND RECENT EARTHQUAKE AND TSUNAMI DISASTERS IN SOUTH ASIA AND
IN THE SOUTHWEST PACIFIC OCEAN
THE
EARTHQUAKE OF 8 OCTOBER 2005 IN NORTHERN PAKISTAN
The Great Tsunami of 26 December 2004 in the
Bay of Bengal and the Indian Ocean
INDONESIA 1883 : Near and Far-Field Effects of
Tsunamis Generated by the Paroxysmal Eruptions, Explosions, Caldera
Collapses and Slope Failures of the Krakatau Volcano in Indonesia,
on August 26-27, 1883
INDIA 2002 - The Earthquake of January 25, 2001
in India
PAPUA NEW GUINEA 1998 - he Tsunami of 17 July
1998 in Papua -New Guinea
INDONESIA 1977 : The Earthquake and Tsunami of
August 19, 1977
INDONESIA 1883 : The Great Tsunami of August
26, 1883 from the Explosion of the Krakatau Volcano ("Krakatoa")
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