Dear Mr. KENT ANGELLO BARUGGA,
This is in response to your request on information regarding the Guinayangan Fault, dated 09 January 2020, and received by our office on 14 January 2020 through the Electronic Freedom of Information Portal.
Based on the latest available active faults map of the DOST-PHIVOLCS, the Guinayangan Fault is an active fault that traverses the central portion of Quezon Province. A fault is defined as active if it has shown movement within the past 10,000 years.
Regarding your question (1) if there are other faults that are connected to the Guinayangan Fault, the Guinayangan Fault is a segment of the Philippine Fault, an approximately 1,200-kilometer long active fault that traverses the whole Philippine archipelago, from Luzon to Mindanao.
Regarding your questions on whether (2) the Guinayangan Fault is capable of generating high intensity earthquakes and (3) is capable of causing damages and casualties on nearby municipalities, the answer is yes on both questions, especially on areas near the active fault.
The Guinayangan Fault is the fault that moved during the 17 March 1973 Magnitude 7.0 Ragay Gulf Earthquake. Intensity VIII ground shaking was reported in Calauag, Lopez and Guinayangan in Quezon. Damaged buildings and infrastructures, landslides, and liquefaction were also reported.
To explain further, the magnitude (M) is the energy released from an earthquake source, while intensity is the severity of an earthquake based on its effects on people, objects and surroundings. Here in the Philippines, we describe earthquake intensity using the PHIVOLCS Earthquake Intensity Scale (PEIS).
Using REDAS (Rapid Earthquake Damage Assessment System) Software modelling, a M7.0 earthquake scenario from the Guinayangan Fault, similar to the 1973 event, induces the same Intensity VIII or very destructive ground shaking near the earthquake source or epicenter. During Intensity VIII of ground shaking, people become panicky and find it difficult to stand, many well-built structures are considerably damaged, liquefaction may manifest on low-lying areas, and landslides may occur on mountainous areas.
The earthquake intensity generally decreases away from the epicenter. So, for the scenario modelled above, Intensity VIII may be felt at the municipalities of Guinayangan, Calauag, Lopez, Buenavista, Gumaca, Macalelon, General Luna, Catanauan, Mulanay and San Narciso in Quezon, and lower intensities will be felt farther from the epicenter.
For more information about the Guinayangan Fault, earthquake hazards, and earthquake preparedness, you may access our website at www.phivolcs.dost.gov.ph. You may also visit https://hazardhunter.georisk.gov.ph or download the Android Mobile App HazardHunter if you want to know the earthquake and volcanic hazards in your area.
We hope that we have sufficiently answered your questions. For additional inquiries, do not hesitate to contact us at +632 8920 7058, or email us at
[email protected].
Your right to request a review
If you are unhappy with this response to your FOI request, you may ask us to carry out an internal review of the response by writing to DOST Secretary Fortunato T. de la Peña and
[email protected]. Your review request should explain why you are dissatisfied with this response, and should be made within 15 calendar days from the date when you received this letter. We will complete the review and tell you the result within 30 calendar days from the date when we receive your review request.
If you are not satisfied with the result of the review, you then have the right to appeal to the Office of the President under Administrative Order No. 22 (s. 2011).
Very truly yours,
Very truly yours,
RENATO U. SOLIDUM, Jr.
