EXPERTS EXPLAIN RECENT EARTHQUAKES
The two inland earthquakes that Fiji felt over the weekend have finally been explained.
They were from the sudden release of stress along a fault rupture in the earth’s crust with unexpected slips in the rock formations.
According to the Mineral Resources Department (MRD), the earthquake events that occurred last Saturday and on Monday in the interior of Naitasiri had a shallow depth source, hence having no direct threat to the whole of Fiji.
Acting director for the Mineral Department, Raymond Mohammed, said the magnitude of the earthquakes were below the line where they issued warnings for areas in danger.
“The majority of earthquake events with similar parameters detected in the Fiji region are not felt due to their location away from land,” a written response to the Fiji Sun stated.
“The inland location and shallow depth of these two events resulted in ground shaking that were felt extensively by the public in the Central Division.
The earthquake on Saturday recorded a magnitude of 3.94 body wave magnitude while the earthquake on Monday recorded a magnitude of 3.31 body wave magnitude. These two events had shallow depth ranges of around six to 11
kilometres.
“Not all earthquakes with the above parameters are felt by buildings and people. From the experiences of the public shared on social media it can be inferred that this is a weak event according to the Modified Mercalli Intensity Scale.”
A weak event means that an earthquake is felt quite noticeably by people indoors, especially on upper floors of buildings. Many people do not recognise it as an earthquake. Standing motors cars may rock slightly. Vibrations are similar to the passing of a truck, with duration estimated.
“Fiji is situated along the most
seismic active zone in the Pacific margin, the so-called ‘Pacific Rim of Fire’. Earthquake events occur and are recorded daily in the Fiji region but they are rarely felt and no it was not triggered by the Tonga Volcanic eruption.”
Mr Mohammed said following such events, Fijians must be aware of any significant changes in homes and surroundings that increases risk and exposure to future threats.
“A temporary increase or decrease in seismicity is part of the normal fluctuation of earthquake rates. Neither an increase nor decrease worldwide/locally is an indication that a large earthquake is imminent,” he said.
Geologist, Dr Kamal Regmi said Fiji was located at the Ring of Fire, making it vulnerable to earthquakes but the small releases or unfelt earthquakes makes Fiji a safe place to be.
“The seismic gap makes it possible for Fiji to be spared from bigger earthquakes,” he said.
“You should notice harm when animals that live in the ground come to the surface during or even after an earthquake.”
Recommendations
Mr Mohammed said members of the public must be vigilant when dealing with a natural disaster that is unpredictable.
The Department recommended the following to be followed:
Be aware and understand that earthquakes cannot be predicted for a timely warning to be issued.
Be prepared and know what to do for any felt earthquake event.
Avoid moving around during shaking to reduce chances of getting injured
It is Safe to DROP to the floor to protect you from falling, take COVER to protect your head and neck under the bed or table and HOLD on to it tightly and move with it until the shaking stops.