Bracing for disaster

Bracing for disaster

MMI Ahyani, Bandung

The massive earthquake and subsequent tsunami that hit Aceh
and other countries sharing the Indian Ocean on Sunday, claiming
thousands of lives, reminds us that we truly live in a
geographically hazardous area.

The entire southern part of Indonesia, starting from Sumatra,
Java, Bali, Nusa Tenggara to Maluku and Papua and also the
northeastern part of the country -- Sulawesi and North Maluku --
constitute active seismo-tectonic regions. Potential volcanic
dangers exist at places along these lines.

Geological technology has been able to map out areas
vulnerable to geological disasters, such as earthquakes, tidal
waves, volcanic eruptions, landslides and the like. However, it
is still impossible to predict when these disasters will actually
hit. Even if a natural disaster is predicted, the accuracy rate
is far from satisfactory. In some cases, scientists making such
wrong predictions can even be charged with a criminal offense for
"disrupting public order and security."

Prior to the recent tragedy, a seismologist from the Center
for Geotechnological Research and Development of the Indonesian
Institute of Sciences in Bandung, Danny H. Natawidjaya, issued a
soft "warning" in this respect during a discussion on the geology
of the Sunda Straits held in Bandung in December 2003.

He said that based on geological research and seismic cycle
records, the possibility of an earthquake measuring 9.0 on the
Richter Scale around the subduction zone in the west of Sumatra
was at the end of its 200-year cycle.

He noted that geological research around Mentawai showed that
the area was hit by major earthquakes in 1381, 1608 and 1833.

Experts have paid a lot of attention to areas around Mentawai
and Siberut because of their history of major earthquakes that
occur in 200-300 year cycles.

This means of course that a major earthquake could hit this
area sometime in the next 50 years. A number of earthquake
monitoring devices have been placed around the Mentawai and
Siberut group of islands.

Existing geological data shows that seismic activity in the
subduction zone of the Mentawai island group have raised them by
some 2 meters. In Mentawai alone, six global positioning
satellite stations have been installed to monitor the movement of
tectonic lithospheric plates.

Data obtained from these stations shows that the islands in
Mentawai have moved three to four centimeters towards Sumatra
each year. The conclusion is that energy is continuing to
accumulate in this subduction zone. Over time, this accumulated
energy must be released through an earthquake.

Speaking here on Monday about his prediction, Danny instead
remarked that the recent earthquake was not one that he had
predicted would occur. Thus it is highly likely that another
similar quake will happen sometime in the next 50 years.

Danny added that movements on the bed of the Indian Ocean can
cause tension on either side of the fault line.

If the accumulation of tension and energy at the sides of the
tectonic lithospheric plates or the subduction zone becomes
unbearable, more fresh earthquakes may occur.

Given this information the public should remain alert and
prepared for potential earthquakes.

This is not a time for blame, though. The expensive lessons we
have learnt must enlighten us to prepare for future disasters.

Of no less importance is to prepare communities living in
disaster prone areas with adequate knowledge.

The writer is a freelance journalist based in Bandung who has
a special interest in environmental and earth affairs.