Palu Tsunami: Unhas Faculty of Geological Engineering Professor: As Predicted

Palu Tsunami, Unhas Geology Professor:

As Predicted

Sunday, September 30, 2018, 9:42 p.m.

Dr. Adi Maulana

Professor of

Geology

at Unhas, Dr. Adi Maulana, was stunned when a massive earthquake followed by a tsunami

struck Donggala and the Central Sulawesi region.

He

recalled the results of his research from about 10 years ago. In one of the chapters

of his dissertation, written about 10 years ago at Kyushu University in Japan,

titled “Petrology, Geochemistry, and Geochronology of Granitoid Rocks

from Sulawesi, Indonesia,” he decided to include a section on

“The Exhumation Process of Granitoid Rocks in Palu, Central Sulawesi.”

This

chapter was quite controversial, as its final conclusion was that the granitoid

rocks in the Sulawesi Neck—known as the Dondo Batholith—exhibit a

rate of exhumation, or uplift to the surface, that is significantly

faster than in any other region in the world.

This

exhumation process is responsible for the exposure of granitoid rocks—which

are, in fact, plutonic or intrusive rocks formed

deep within the Earth—and for the formation of Mount Dondo, which rises to a height of more than

2,000 meters. These granitoid rocks extend from the Palu area to Toli-Toli,

Central Sulawesi.

Based on

the results of electro-probe microanalysis (EPMA), particularly the mineral chemistry data for

plagioclase, biotite, and hornblende, combined with age data from

argon dating of biotite and hornblende, Maulana calculated

the geothermobarometry of these granitoid rocks. He concluded that

the exhumation rate of granitoid rocks around the Sulawesi neck,

particularly near the city of Palu, reaches 2.7 mm/year.

These

results indicate that the exhumation rate in the Palu area and its surroundings

is extremely rapid and is surpassed only by the exhumation rate of granitoids

in the Himalayan Mountains.

The conclusion

in that chapter is: _The rapid exhumation rate of the Sony Pluton (near Palu)

is attributed to the active vertical movement of the Palu-Koro Fault Zone, which

has been active since the Pliocene. This indicates that faulting may play an important

role in the differential exhumation of intrusive bodies within an orogenic belt._

"Based on

this conclusion, I hypothesize that the Palu-Koro Fault exhibits

vertical movement in addition to being predominantly described by many experts as

a strike-slip fault," wrote Maulana.

Ultimately,

this was proven when the Palu-Koro Fault moved and subsequently triggered

a tsunami, Maulana said.

“May

the people of Palu always be protected and granted the strength to endure

this disaster. May we be able to build a better and

more comprehensive system for disaster mitigation in the future so that loss of life can

be minimized,” Maulana expressed in his writing regarding the Palu Tsunami.

Currently,

Maulana is finalizing a draft paper that has been delayed for two

years on the tectonic evolution of Central Sulawesi based on geochemical

and geochronological data, particularly zircon dating data.

This

year, Maulana and several geologists from National Taiwan University—sponsored by

an international research consortium from Taiwan under the theme “Geology of the

Silk Road”—will collect even more data

on isotopes and zircon dating from all igneous rocks found in

Sulawesi.

This

research is expected to take approximately 5 years and is anticipated to produce a

more detailed tectonic model of Sulawesi for various purposes.