[Kabar-indonesia] 'Weak' Quake Believed Cause of Java Tsunami - Lessons To Be L earned

[Joyo at aol.com]

also: World leaders offer RI condolences and assistance

Yomiuri Shimbun
Saturday, July 22, 2006

'Weak' quake believed cause of Java tsunami

- Lessons to be learned

Eiji Noyori / Yomiuri Shimbun Staff Writer

The earthquake that hit the area southwest of Java,
Indonesia, on Monday, and caused a tsunami that killed
more than 500 people, is believed to have been of a
type that produces weak tremors, which made it
difficult for Javanese to realize a killer wave was
approaching.

The area that stretches from Java to Sumatra is where
strong earthquakes occur most often in the world. In
December 2004, a quake in the region caused a tsunami
that claimed the lives of about 230,000 people around
Asia.

The India-Australia Plate dips below the Eurasian
Plate in this area. At the point where these tectonic
plates meet, frictional stress accumulates inside the
Earth's bedrock. When the bedrock succumbs to this
stress, it causes a quake.

According to the U.S. Geological Survey, the epicenter
of Monday's earthquake was in the Indian Ocean about
360 kilometers south of Jakarta. The depth of its
focus was shallow, at about 10 kilometers.

The USGS has concluded it was highly likely the
bedrock in the area was subjected to a reverse fault
mechanism, in which one part of the bedrock is forced
upward.

But Tokyo University's Earthquake Research Institute
has taken the view that the quake occurred because the
bedrock fragmented.

Research in Java will be needed before it can be
determined which mechanism caused the quake.

Japanese seismologists have also studied the speed of
the fracture that caused the earthquake.

In the case of most tectonic movements, which
generally cause the strongest tremors, the speed at
which the bedrock shifts is usually 2.7 to 2.8
kilometers per second.

But according to Yuji Yagi, associate professor at
Tsukuba University, the speed of bedrock movement in
Monday's quake was estimated at just 1.5 kilometers
per second.

However, the magnitude of the earthquake was huge at
7.7, and its depth of focus was extremely shallow,
creating the right conditions for a tsunami.

"The movement of the bedrock slowly raised the sea
level , which led to the huge tsunami. However, [due
to the slow movement] the tremors were hard to
detect," Yagi said.

"As a result, it's highly likely this was a
tsunamigenic-type quake, which causes huge waves
despite only producing weak tremors on the ground," he
said.

Seismologists believe the Javanese tourist area of
Pangandaran--where many people were killed--was hit by
a tsunami with a crest nearly one meter tall.

Though details about the strength of the tremors that
hit Java are not known, many seismologists assume many
of the victims did not notice an earthquake had
occurred and therefore failed to evacuate, which
contributed to the high death toll.

Lessons to be learned

Japan also has been hit by unexpected tsunami.

In the Meiji Sanriku Earthquake in 1896, which killed
about 22,000 people, most of the victims were drowned
by a tsunami. But the strength of the tremors felt in
the coastal areas that were hit was only about 2 or 3
on the Japanese seismic intensity scale of 7.

In 1960, a tsunami caused by a quake off Chile reached
the Pacific shores of the Tohoku region 22 hours after
the quake occurred, killing 142 people.

Nihon University Prof. Nobuo Shuto has highlighted the
need to learn lessons for disaster prevention from the
history of natural disasters.

"It's essential to improve disaster-prevention
education and teach residents in coastal areas that
they should evacuate to higher ground as soon as they
feel tremors, even if those tremors are very weak," he
said.

"This lesson should be taught around the world, not
just in Japan where systems to monitor tsunami are
well established," Shuto said.

Using lessons learned from the tsunami caused by the
Sumatran quake, Japan, Indonesia, Thailand and other
nations with Pacific coastlines conducted in May an
emergency exercise to test their ability to relay
tsunami information via a warning network they have
built. And international cooperation to prevent
tsunami disasters has already progressed.

Following the Java quake, some authorities, including
the Meteorological Agency's Northwest Pacific Tsunami
Advisory Center and the U.S. Pacific Tsunami Warning
Center notified the Indonesian authorities of the risk
of a tsunami. However, despite this alert, the warning
is thought not to have reached many residents of Java,
partly because of the lack of communication equipment
in the affected areas.

Under the initiative of UNESCO, an early warning
system for tsunami is being built in the Indian Ocean.
The system will use buoys to detect abnormal movement
on the sea surface and will send the information to
monitoring centers via satellite.

But the initiatives, including some in Indonesia, have
not been easy to set up. "There are many countries
that haven't been able to establish monitoring
systems," a Meteorological Agency official said.

The seriousness of the Java tsunami has highlighted
again the importance of preparedness for tsunami
centering on early warning systems and improvement of
awareness of earthquakes among people living in
coastal areas.

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The Jakarta Post 
Saturday, July 22, 2006

World leaders offer RI condolences and assistance

Kurniawan Hari, The Jakarta Post, Jakarta

World leaders, including North Korea's second man, continued offering 
condolences to the public and the government of Indonesia over the 
earthquake-triggered tsunami that hit the south coast of the densely-populated Java Island.

A tsunami triggered by a magnitude 7.7-earthquake slammed into the southern 
coast of Indonesia's Java Island on Monday.

North Korea's second man Kim Yong-nam expressed "deep sympathy" to Indonesian 
President Susilo Bambang Yudhoyono and victims and residents of the affected 
region, AP reported Friday, quoting an article from the North's official 
Korean Central News Agency.

Kim is head of the Presidium of North Korea's parliament, second in line 
behind leader Kim Jong-il, and serves as his country's ceremonial head of state.

Indonesia and North Korea have historical ties. Indonesia's first president, 
Sukarno, was a close friend of leader Kim's late father, Kim Il-sung. 
Sukarno's daughter, Megawati Soekarnoputri, was Indonesia's president between 2001 and 
2004 and has kept up a friendship with Kim Jong-il.

Indian President A.P.J. Abdul Kalam also expressed condolences for the 
victims of the disaster and wished an early recovery for those injured.

"On behalf of the government and the people of India and my own behalf, I 
would like to express our heartfelt sympathy and condolences to the people of 
Indonesia who have lost their near and dear ones in the tsunami that struck the 
southern coast of Java," he said in a statement, a copy of which was made 
available Friday to The Jakarta Post by the Indian Embassy in Jakarta, sent to 
Yudhoyono.

President Pervez Musharraf and Prime Minister Shaukat Aziz of Pakistan also 
offered condolences.

"I am deeply grieved at the loss of lives and damage to property, caused by 
the tsunami. I would like to convey on behalf of the people and government of 
Pakistan deepest condolences to the bereaved families and sympathy," Musharraf 
said in a message for President Yudhoyono. A copy of the statement was sent to 
the Post by the Pakistani Embassy here Friday.

Malaysian Prime Minister Abdullah Ahmad Badawi meanwhile said that his 
country was ready to provide humanitarian aid.

"I offer my sympathy over the tsunami that has claimed lives and caused 
destruction," he said in a statement sent by the Malaysian Embassy in Jakarta.

Meanwhile, Australian Ambassador to Indonesia Bill Farmer announced that 
Canberra will provide A$250,000 for emergency relief and short to medium term 
assistance.

The funding comprises $200,000 through international aid agencies and 
non-governmental organizations to restore the water supply and sanitation services, 
reequip schools and reestablish livelihoods with a focus on fishing communities.

A further $50,000 will be provided to the Indonesian Red Cross for emergency 
and relief supplies for affected communities. 

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Joyo Indonesia News Service
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