TEMPO.CO, Jakarta - The Head of Tanjungpinang's Meteorology, Climatology, and Geophysics Agency (BMKG), Hartanto, said that the earthquake felt in Natuna Regency, Riau Islands Province, which measures between 2 to 3 on the Modified Mercalli Intensity (MMI) Scale, is an unusual phenomenon.
"Natuna is not located on an earthquake prone area, nor there are any volcanoes in the area - as such, earthquakes in the area is highly unlikely to happen," said Hartanto on Thursday, June 25, 2015.
It is known that the earthquake, which was recorded at 01:22 AM Western Indonesia Time (WIB), was felt only for a couple of seconds, but the exact cause behind the phenomenon has yet to be found.
The vibrations were not detected by seismographs in the area - which are designed by default to detect even the smallest seismic anomalies.
Hartanto continued that earthquakes of that scale are usually only felt, but not detected by seismographs. "Once an earthquake registers on seismographs, it is no longer measure by the MMI scale, but the Richter scale," Hartanto said.
The phenomenon has since been reported to BMKG's central headquarters to be analyzed with more sophisticated equipment - that said, even BMKG's central headquarters with its' more sophisticated equipments, did not detect any anomalies related to the phenomenon.
"As such, we could not conclude and thus explain the cause of the supposed quake - we don't even know whether the cause lies beneath the earth's crust or not," Hartanto said.
Hartanto said that such vibrations could usually be explained by incidents such as landslides, or bombings. "That said, we have not received any reports of such incidents occurring when the quake was felt and reported," Hartanto added.
ANTARANEWS