Chances of a stronger earthquake striking Central Visayas are “slim” and no new volcano is forming in Bohol.
Director Renato Solidum of the Philippine Institute of Volcanology and Seismology (Phivolcs) yesterday issued this statement to allay fears and quash text rumors of a supposed impending bigger earthquake after last week’s 7.2 magnitude temblor. The rumor of an 8.0 followup quake also went viral in the Internet.
“There’s a very small chance for another stronger earthquake there. No device can ever predict an earthquake. It is best to consult proper authorities to clarify these kinds of messages,” Solidum said in a news conference in Manila.
“Yung fault na gumalaw ay nag-release na ng enerhiya na napakalakas, 7.2. So pambihira po na ganun kalakas na lindol at ganun lang at hindi naman ganun kahabaan ay mag-ge-generate pa ng magnitude 8. Hindi tayo umaasa na magnitude 8 pa yung lugar na yan. Imposible,” he said.
(The fault that moved released a strong energy, 7.2 magnitude. It’s an unusual earthquake. We’re not expecting that a magnitude 8 would come from the same fault.)
Solidum said it would take another hundred years to generate a new quake in that same fault plane that is as strong as the one that struck last Tuesday.
The Phivolcs chief said aftershocks would continue for weeks and would eventually decline.
“There’s a very slim chance that stronger quake will strike. Just like what happened in Negros in 2012, the aftershocks that followed were weaker,” he said.
In the Cebu Provincial Board session yesterday, the same message was echoed by Jeffrey Perez of the Phivolcs’ Geological Disaster Awareness and Preparedness Division.
Perez is part of the team sent by Phivolcs to Cebu and Bohol to monitor the aftermath of the Oct. 15 quake.
“Earthquakes cannot be predicted. If there are messages forecasting an earthquake and claims it comes from us (Phivolcs), please do not forward that message anymore,” he said.
PB Member Miguel Magpale asked Phivolcs to coordinate with the provincial Public Information Office in sending public advisories. .
PB Member Sun Shimura asked about the safety of their districts from earthquakes.
Perez replied that no single area in the country is exempted from a quake.
“It’s not really about the location of faults, it’s the level of ground-shaking that these faults can produce,” Perez said.
“It does not mean that if a certain place is not located near a fault line, it will not be affected. Chances are the place will still be affected like Cebu when the quake hit Bohol,” he added.
Perez also explained why Tuesday’s quake did not trigger a tsunami.
“It was tectonic in nature meaning it originated from the land and not from the water,” he said.
Perez called for programs on earthquake-preparedness since there is “no known method to predict a quake.”
“Disaster preparedness – that’s where we have to focus because we don’t have control over these events,” he said.
Vice Gov. Agnes Magpale said Perez’ presentation will help the PB identify problem areas in disaster preparedness, specifically on the implementation of the National Building Code.
She said the PB will look into legislation that will require stricter compliance of the code especially on the construction of public structure such as school buildings.
“That is why we called for this presentation so that we can have more background about earthquakes in aid of legislation,” Magpale said.
The PB yesterday authorized Cebu Gov. Hilario Davide III to use the provincial government’s P70 million calamity fund for continuing relief operations in Cebu and Bohol.
Hidden fault
Last Tuesday’s earthquake was generated by a fault plane other than the initially suspected East Bohol fault.
Solidum said that in their study in 2007, Phivolcs identified three fault planes in Bohol — the north and south offshore and East Bohol fault. Tuesday’s quake was likely triggered by the north offshore fault.
Solidum said the existence of the fault, which was defined as a hidden or blind fault, was postulated in 2007 but it was only validated with last week’s earthquake.
The epicenter of the Bohol quake was between Catigbian and Sagbayan towns.
At least 16 geologists, seismologists, civil engineers and information specialists from the Department of Science and Technology and Philvolcs are in Bohol and Cebu to assist local officials.
Liquefaction
Solidum also dismissed talk that a volcano was forming after the quake. He said that what actually happened was liquefaction, a process where water-saturated soil is changed into liquid.
Some areas reported that mud with water that had a pungent smell had appeared.
“Many hoax texts spread last night and kept me awake. Is there a volcano forming in Bohol? None. It’s impossible for Bohol to have a volcano. The foul-spelling mud and water that were seem seeping out of the ground was caused by escaping sulfur dioxide gases that were trapped beneath the earth’s surface,” said Solidum.
Aftershocks
As of 10 a.m. yesterday, there were 2,255 aftershocks following the Oct. 15 Bohol quake.
Five days after the earthquake struck, the Southern Leyte substation of Phivolcs recorded at least 2,000 aftershocks as of Saturday night.
Dr. Jane Punongbayan of Phivolcs said a thousand more would have been recorded if there was a substation within the area of the hardest hit towns in Bohol.
One of the strongest aftershocks was felt late Friday afternoon in the town of Catigbian.
“It was really a rumbling sound. (I heard) rumbling of roofs. People were crying,” Punongbayan recalled when her team from Phivolcs and the University of the Philippines National Institute of Geological Sciences (UP NIGS) surveyed the town.
“They will be experiencing intensity 2 to 3 earthquakes that they would not mind. But in a day, they will be awakened by an earthquake that’s quite strong. And every several days, there will be a strong earthquake that is capable of bringing down already weakened structures,” Punongbayan explained.
Nearer the region of the epicenter, tremors occur every 10 minutes. They will die off after two to three weeks, according to Phivolcs.
Punongbayan added that in Bohol’s northern towns of Buenavista, Inabanga, and Clarin, the main shock – the largest earthquake in a sequence of quakes – on Tuesday reached close to intensity 8, which she described as “very destructive.”
The strong ground shaking destroyed houses, flattened churches, shattered roads, knocked down bridges, cut off power and communication lines, and isolated towns.
Death toll rising
The Bohol quake has so far claimed 186 lives –173 in Bohol, 12 in Cebu and one in Siquijor.
Eleven person remain missing, all from Bohol.
The quake also affected 3 million people in Central Visayas, with about 109,000 people housed in shelters
Many Boholanos said they live in constant fear and feel desperate. But signs of early recovery were reported beginning Saturday.
The provincial government and the private sector are slowly restoring infrastructure and communication lines. Commerce is returning to normal.
Several classrooms sustained heavy damage, forcing the province to keep classes suspended for another week. /Inquirer with correspondent Peter Romanillos