THE two consecutive earthquakes that jolted Eastern Leyte and Bukidnon last week created panic in the affected communities.
While
the impact of the magnitude-7.6 earthquake that hit Eastern Leyte and
the magnitude-5.6 earthquake in Bukidnon was minimal because very few
people inhabit the areas hit, they nonetheless struck fear in the hearts
of Filipinos, aware that the country itself is on the Pacific Ring of
Fire.
Remembering the 1990
earthquake that brought down vibrant Baguio City, the country’s summer
capital and a prime tourist destination, to its knees, the question
lingers: What would happen if an earthquake of such strength hit Metro
Manila in the dead of the night? Or even during hours when people are in
their workplaces?
With
an estimated population of 12 million and towering residential and
commercial buildings scattered all over it, what would be the impact of a
magnitude-7.2 earthquake when it hits Metro Manila?
Still
recovering from the effects of Tropical Storm Ondoy in the last quarter
of 2009 and the heavy rains induced by the hanging habagat, or
southwest monsoon, just last month, disaster preparedness initiated for
the inundation remains sadly wanting.
Earthquakes
are considered far deadlier than other natural calamities, their impact
on lives and property far more severe than the flash floods that
residents of Metro Manila and other low-lying areas in the provinces
have experienced with intense typhoons, heavy rains and widespread
floods, which are, in fact, now being considered the “new normal”
because of the advent of climate change.
Earthquakes
are known to cause buildings and bridges to collapse, trigger
widespread fires, cut power, water and means of communications, create
tidal waves or tsunamis and wipe out entire cities from the map, such as
the one that triggered a tsunami and eventually a nuclear crisis in
Japan.
A study
conducted by the Philippine Institute of Volcanology and Seismology
(Phivolcs) in 2004 showed that one strong earthquake—with a magnitude
ranging from 6.5 to 7.9 on the Richter scale—can devastate Metro Manila
and create complete chaos, even without the aggravating circumstances of
a nuclear disaster as had happened in Japan.
Metro
Manila lies along the path of several fault lines, including the West
Valley Fault and the East Valley Fault, which makes it “highly at risk.”
The
study, titled “Earthquake Impact Reduction Study for Metropolitan
Manila in the Republic of the Philippines,” was conducted in
collaboration with the Metropolitan Manila Development Authority and the
Japan International Cooperation Agency. The study developed 18
earthquake scenarios, and provided concerned government agencies a
picture of what could happen should such a devastating earthquake take
place.
The
distribution of ground motion, seismic intensity, liquefaction potential
and slope stability were calculated for the earthquake scenarios by
experts that pictured a “doomsday” scenario for Metro Manila, the seat
of economic and political power in the Philippines.
Three
of the scenarios—the West Valley Fault, the Manila Trench and the 1863
Manila Bay—could cause severe damage to Metro Manila, according to the
study.
The West
Valley Fault and the East Valley Fault that run north to south along the
west and east edge of Marikina Valley are thought to pose the greatest
threat to Metro Manila due to their proximity, the study said.
According to the study, a magnitude-6.5 to 7.9 earthquake striking Metro Manila is no longer in doubt.
“The likelihood of an earthquake of such magnitude to happen is certain. What
we are not sure about it is when it will happen,” Ishmael Narag,
officer in charge of the Seismology Division of Phivolcs, said.
A magnitude-7.2 earthquake, one of the scenarios developed, can devastate Metro Manila.
With such magnitude, people are forcibly thrown to ground. Many cry and shake with fear. Most buildings are destroyed. Bridges and elevated concrete structures are toppled or destroyed. Numerous utility posts, towers and monuments are tilted, toppled or broken. Water sewer pipes are bent, twisted or broken. Landslides and liquefaction with lateral spreadings and sand boils are widespread. The
ground is distorted into undulations. Trees are shaken very violently,
with some toppled, broken or uprooted. Boulders are commonly thrown out.
River water splashes violently on slopes over dikes and banks.
In
the first hour, according to the study, its impact is estimated to
destroy 168,300, or 12.7 percent, of the 1.33 million residential
buildings in the metropolis, and damage 339,800, or 25.6 percent.
Of
the estimated 9.93 million people of Metro Manila, some 34,000, or 0.3
percent, would die, 90 percent of them inside the collapsed buildings;
at least 113,600, or 1.1 percent, of the total population would sustain
injuries. The injured may suffer trauma and bone fractures caused by the
collapsed building and falling furniture.
The
figure, according to the study, includes trapped people who are not
immediately rescued from collapsed buildings and who may eventually die.
But the study revealed that in case of such a strong earthquake, the number of fatalities in squatter areas would be minimal.
In
the next three to seven days, aftershocks would cause further building
damage and some 1.26 million people would lose their homes and would
have to seek shelter elsewhere for safety.
Habitation in high-rise residential buildings would become impossible.
As
the earthquake inflicts damage on buildings, electric cables and
telephone posts are tilted and broken; there would be no power and
electricity, no means of communication and even water supply as the
movement of the ground could also severely damage water facilities—and
the main sources of water for Metro Manila’s supply, the La Mesa Dam.
Worse,
public buildings, such as hospitals, schools, even fire departments,
police and even local government units (LGUs), could be heavily damaged,
making it difficult for rescue, relief and eventually rehabilitation
effort more difficult.
The
study estimated that of the 981 medium-rise buildings (10 to 30
stories), 11 percent would be destroyed and 27 percent damaged; of the
119 high-rise buildings (30 to 60 stories), 2 percent could be destroyed
and 12 percent damaged.
The
expected simultaneous outbreak of fires in about 500 different areas
could be triggered by electricity short circuits. Fire in factories,
hospitals, residential kitchens, petroleum and LPG leakages from storage
tanks could also happen simultaneously within an hour after the
earthquake.
Runways in airports could be damaged, and airports could encounter problems as a result of damage to airport facilities. Eventually, runways would be closed and only helicopters would be available.
Ports
and harbors could also be damaged and tilted by liquefaction, while
severe damage to roads and bridges would render major roads impassable,
making distribution of relief goods, food, shelter and, more important,
medicines for the injured and the sick in evacuation centers more
difficult.
The
scenarios also indicate that even Malacañang, the House of
Representatives and the Senate buildings would suffer damage, as well. Official functions would be severely limited, therefore.
But
Narag was quick to note that since the study was conducted and
completed in 2004, Phivolcs and other concerned agencies have been
closely coordinating to strengthen and prepare for the worst-case
scenarios.
He
said, in fact, the upgrading of the National Disaster Coordinating
Council to the National Disaster Risk Reduction and Management Council
was a major step in putting in place disaster-risk reduction plans
against all kinds of natural calamities, including devastating
earthquakes.
According
to Narag, the study’s recommendations and action plan were already
integrated in the master plans of various government agencies and some
LGUs.
“The Department of Education and other concerned agencies are continuously conducting earthquake and fire drills in schools. The
Department of Public Works and Highways is also looking into the
structural defects of buildings and is making sure that proper
engineering designs are in place,” he said.
The Department of Health, he said, had also crafted a master plan in case of such disaster.
The
Philippine National Police and the Bureau of Fire Protection, he said,
are also well aware of what to do in case of such national emergency.
“Even
LGUs are strengthening their disaster risk-reduction strategies, and
earthquake is one of those they are preparing for,” he said.
Some barangays, in fact, are conducting their own earthquake, flood and fire drills, he added.
The study urged concerned government agencies to prepare and draft master plans to reduce the risk of disasters.
But Narag said the impact of a devastating earthquake as developed in the 2004 study needed updating.
He
said that by now, the number of people living in Metro Manila has gone
up. There are also more residential and commercial buildings, as well as
public infrastructures such as bridges and flyovers.
According
to Narag, the impact of a devastating earthquake in Metro Manila is
expected to radiate to neighboring towns and cities in the provinces
near it. Even Rizal, Cavite, Laguna, Bulacan and Pampanga
may be severely affected and their governments would not be able to
provide help for Metro Manila because they would also need to look after
their own people.
“The impact of an earthquake could be worse if we are not prepared for it. That’s why our ongoing risk-assessment project covers even floods and other geological hazards,” he said.
Narag
said proper information, education and communication is important to
make people aware of the potential impact of strong earthquakes and what
needs to be done in case of emergency.
According
to Narag, Phivolcs, in collaboration with the Australian Government
Overseas Aid Program, the Philippine Atmospheric, Geophysical and
Astronomical Services Administration, the Mines and Geosciences Bureau
and the National Mapping and Resource Information Authority and
concerned LGUs, is conducting similar “risk analysis projects” to
include the possible impact of a devastating earthquake on neighboring
provinces such as Rizal, Cavite, Laguna in the south, and Bulacan up to
Pampanga in the north.
The
new study, he said, would be comprehensive and hopes to come up with,
like the 2004 study, sets of recommendations and action plan designed to
reduce the risk of disasters as a result of a devastating earthquake.
“We are targeting the release of the study by the end of March next year,” he said.
The
new study, he said, will update data and records, such as the
population, number of residential and commercial buildings, identify
schools and hospitals, pinpoint bridges and overpasses, and other public
infrastructures that are potentially at risk in Metro Manila, as well
as in Rizal, Cavite, Laguna, Bulacan and Pampanga. The study, he said, would also come up with recommendations to help prepare the various stakeholders in case of such tragedy.
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