Continuing aftershocks, hoaxes: Quake jitters grip Central Visayas

CEBU, Philippines - Quake-hit areas in Cebu and Bohol woke up to strong aftershocks early yesterday morning, which continued throughout the day but authorities appealed to the public not to panic and to filter information that is spread through social media and text messages.

Geologist Jeffrey Perez from Philippine Institute of Volcanology and Seismology (PHIVOLCS) clarified last night that their agency did not release information about a strong earthquake that will reportedly hit Cebu and Bohol.

"We did not mention any fault near Sagbayan, Bohol or a magnitude 8 na lindol. We mentioned a blind fault but never West Valley fault. Dun sa mga kumakalat na text message and information online, wag na po i-propagate," Perez clarified.

A message that warned of an impending earthquake was circulated over text messages, as well as social media site Facebook.

"NEWS ALERT!!! A MUST READ on Oct. 20, 2013 via TV5 PHIVOLCS reported that there is a blind fault line located in Sagbayan, Bohol. If the West Valley fault will move, they expect all Visayans especially Boholanos to prepare for the (8.0 magnitude)!!! Which will also affect CEBU!!! Please pass," read the circulated message.

Television station TV5, with account name News5 Everywhere, posted a clarification last night in its Facebook and Twitter accounts.

"Good evening everyone, please stop sharing the 'Blind fault located in Sagbayan, Bohol..' This report is not true. It causes panic to some Cebuanos and Boholanos. Thank you," the online post read.

"Nandito nga tayo to appease the people and conduct information dissemination tapos may kakalat pang ganyang report. Nakakalungkot lang. Sana naman wag ganyan," Phivolcs' Perez said.

Perez, who is the Supervising Science Research Specialist and geologist from PHIVOLCS Geological Disaster Awareness and Preparedness Division, is in Cebu together with other officials from national office to document the strong quake that hit this part of Central Visayas.

Seismologists, geologists, engineers, documentation staff comprise the two PHIVOLCS teams deployed in Cebu and Bohol.

"A 10 man team is currently in Bohol. In Cebu, we are a 5 man team with four from Manila and one from Mactan office. Apart from assessment, we also conducted information dissemination campaign particularly to Boljoon town which is part of the rupture zone," he explained.

Perez presented the initial findings of the two teams during the command conference at the Cebu City Hall with Mayor Michael Rama and department heads last night.

After the physical assessment, PHIVOLCS advised those living in quake-hit areas not to enter heavily damaged structures and avoid areas where damage is visible.

They also clarified reports of a new volcano in Cebu or Bohol, or that a stronger quake will hit the region.

"Wala pong bulkan na tumutubo sa Bohol o Cebu. Yung earthquake is due to a blind fault... Aftershocks could last to two to three weeks pero humihina ito habang tumatagal... Napakaliit ng chance of bigger earthquake to hit Central Visayas," Perez said.

The mayor said the public should not believe information that does not come from legitimate sources.

"For any advisory, they should not believe any information particularly on earthquake if it's not coming from PHIVOLCS," Rama said.

The visiting PHIVOLCS team also recommended to conduct stress debriefing for students especially that strong aftershocks continue to be felt in Cebu and Bohol.

Meanwhile, Phivolcs director Renato Solidum said that as of 12 noon yesterday, a total of 2,078 aftershocks were recorded from the magnitude-7.2 quake that hit Bohol and Cebu last week that killed at least 185 people. Only 39 of these aftershocks, he added, were reportedly felt.

He said aftershocks could cause additional damage to "already damaged houses and buildings or cause landslides in areas already destabilized and (in) unstable slopes."

No new fault

Solidum also clarified that the magnitude-7.2 tremor that struck Bohol was not triggered by a new fault.

"That one (fault, north offshore of Bohol) is a hidden or blind fault, it does not appear at land surface," the Phivolcs chief said.

"We already postulated its presence possibly offshore of Bohol when we did the ground shaking hazards assessment in 2007 under the United Nations-funded READY project, that is why we estimated Intensity 7 to 8 shaking at northern side of Bohol," he explained.

Earlier, Ismael Narag of Phivolcs said that the powerful quake that rocked Bohol and Cebu last Oct. 15 could be triggered by the new fault system and not the East Bohol fault.

Solidum said they initially indicated the East Bohol fault as the epicenter of the deadly quake based on the data received from their instruments.

He also said electricity was cut in most parts of the areas devastated by the quake, preventing them from getting more information.

"The orientation of the postulated fault was not defined because of few earthquake events but with the current earthquake events we will be able to image this better," he said.

Solidum said they have installed five additional seismographs after the main shock to properly locate smaller aftershocks.

He also said the agency has ongoing active faults mapping.

"Phivolcs geologists map the active faults using our regular fund or sometimes part of international collaboration like READY projects but our experts mapped the active faults in this project," he said.

Solidum said they have an ongoing review of active faults in Mindanao with the Japan International Cooperation Agency.

Solidum said everybody should be prepared for earthquake even though they are far from active faults as ground shaking and other hazards could affect them.

"Cebu is very far from the epicenter of the quake but it was affected by ground shaking," Solidum said. — with PhilSTAR News Service/QSB