GEOLOGIC HAZARDS: IMPACTS, CHALLENGES AND PREPAREDNESS LEO VAN V. JUGUAN, CESO V Regional Director DENR, Mines and Geosciences Bureau Region 6 TYPHOON YOLANDA, NOVEMBER 2013 TYPHOON YOLANDA, NOVEMBER 2013 6,340 death toll ST. BERNARD, GINSAHUNGON, LEYTE, FEBRUARY 2006 SOURCE: CENRO ILOILO ST. BERNARD, GINSAHUNGON, LEYTE, FEBRUARY 2006 1,126 death toll The 2006 Leyte, Philippine Debris Avalanche CHERRY HILLS LANDSLIDE (1999) GEOLOGIC HAZARDS: What are they? BRGY. CAWILIHAN, LEON, ILOILO GEOLOGIC HAZARDS • Earth processes occurring as IRREGULAR EVENTS in which, its direct interaction with the material environment is CAPABLE OF CAUSING SIGNIFICANT NEGATIVE IMPACT ON MAN’S LIFE AND WELL-BEING; • EXAMPLES: LANDSLIDES, FLOODS, EARTHQUAKES, STORM SURGES, etc. Philippine Setting Prone to GEOHAZARDS • Within the Ring of Fire • Within the Earthquake Belt • Within the Pacific belt of tropical cyclone (average of 20 TYPHOONS A YEAR) WHY DO WE HAVE GEOLOGIC HAZARDS? Continental Drift WHY DO WE HAVE GEOHAZARDS IN THE PHILIPPINES? Location of most of the world’s volcanoes and earthquake generators (e.g. trenches, faults, etc.) Highly prone to geologic hazards (e.g. volcanic eruption, earthquake, landslide, etc.) Potential for mineralization (formation of metallic deposits, etc.) is also high Porphyry Cu belts Philippines Porphyry Cu belts WHY IS THE PHILIPPINES GEO-HAZARD PRONE: • Numerous active Faults and Trenches • Numerous volcanic belts and active volcanoes • Generally mountainous terrain and steep slopes Tectonic Map of the Philippines Source: PHIVOLCS Negros Oriental Earthquake Mineral Central Cordillera Districts (Cu, Au, Fe) Zambales (Cr, Ni, Pt, Cu, Paracale Au) (Au, Fe, Cu, Ni) Masbate (Au) Negros Eastern (Cu, Mindanao Au) (Cu, Au, Ni, Cr) Zamboang a (Cu, Au, Cr) WHAT IS A LANDSLIDE ? Downward movement of soils, rocks and other debris due to Not always fast ! TRIGGERING MECHANISMS: heavy rainfall CONTRIBUTING FACTORS (Landslides) A. LOCATION / TOPOGRAPHY B. SLOPE ANGLE C. ROCK / SOIL TYPES D. DEGREE OF WEATHERING / ALTERATION IN THE ROCKS / SOIL E. PRESENCE AND ORIENTATION OF STRUCTURES F. PRESENCE OF WATER G. HISTORY OF LANDSLIDE OCCURRENCES IN THE AREA H. HUMAN INITIATED EFFECTS (AS AGGRAVATING FACTOR) PICTURE TAKEN IN IGBARAS, ILOILO Picture - Brgy. Ingay, Leon, Iloilo Brgy. Cunsad, Alimodian, Iloilo, August 1, 2012 Landslide Head Landslide Head Sliding Plane Old cracks and the sliding plane at the landslide head with very smooth and oxididized surfaces. Photos of houses near the head of the landslide. The residents living in these houses were relocated to the barangay proper of Brgy. Cunsad. Brgy. Cunsad, Alimodian, Iloilo,August 2012 Landslide after TS Gener in July 2012, Head Base Approximately 10.5 hectares of farmlands were affected/ destroyed by the recent landslide in Brgy. Buenavista, Tubungan, Iloilo. Day Care Center and Ricefields, Brgy. Buenavista, Tubungan BACOLOD NATIONAL HIGH SCHOOL, MAY 2011 BACOLOD NATIONAL HIGH SCHOOL, AUGUST 2011 Active landslides in the Transcentral Highway, Negros Occidental (2010) BRGY. QUINTIN REMO, MOISES PADILLA, AUGUST 9, 2009 BRGY. QUINTIN REMO, MOISES PADILLA, FEBRUARY 8, 2010 BRGY. QUINTIN REMO, MOISES PADILLA BRGY. QUINTIN REMO, MOISES PADILLA Photo Credits: PAG-ASA What is flood? “Too much water at the ‘wrong’ place!” FLOODS occur when a large amount of water overflows beyond its normal confines, especially what is normally dry land. What is flood? “Too much water at the ‘wrong’ place!” What causes flooding? Heavy rainfall Dam or dike failure Storm surge (coastal areas) Other Causes of Flooding: Land subsidence, outdated/clogged drainage structures, reduced channel capacities due to siltation and encroachment of structures What is flood? “Too much water at the ‘wrong’ place!” FLOODED AREAS IN CAGAYAN DE ORO DURING TYPHOON SENDONG December 2011 FLOODED AREAS IN CAGAYAN DE ORO DURING TYPHOON SENDONG BEFORE TYPHOON SENDONG AFTER TYPHOON SENDONG Manila August 15, 2007; Typhoon Egay Photo from Getty Images by AFP/Getty Images TS “SENDONG” December 2012, Southern Mindanao newsinfo.inquirer.net TY “ONDOY” September 2009, NCR and Luzon TY “PEPENG” September 2009, Luzon TS “QUINTA” December 2012, Visayas & Mindanao Typhoon Quinta, December 2012 Photo Credits: ABS-CBN Iloilo Photo Credits: ABS-CBN Iloilo Dingle town proper, during Typhoon Quinta, December 2012 Sta. Barbara Airport Resettlement Area Photo Taken 2007 After Typhoon Frank, 2008 Photos from DENR 6 Libacao, Aklan AKLAN RIVER, LIBACAO TO KALIBO, AKLAN KALIBO, AKLAN SIBALOM RIVER, SIBALOM, ANTIQUE Sea Level Rise and Storm Surge TYPHOON YOLANDA, NOVEMBER 8, 2013 IMPACTS LOSS OF LIFE . DAMAGE TO PROPERTIES . LOSS OF LIVELIHOOD . INTERRUPTION OF ECONOMIC, SOCIAL AND OTHER HUMAN ACTIVITIES . DISPLACEMENT . TRAUMA What can be done? …and what has been done… The National Geohazard Assessment and Mapping Program The DENR-MGB National Geohazards Mapping and Assessment Program An on-going priority program of the DENR-MGB that aims to: identify areas in the country that are susceptible or vulnerable to various geologic hazards, and increase public awareness in order to lessen or mitigate the negative impacts of these events. Generation of Geohazard Maps LANDSLIDE POTENTIAL = Infrastructures + Vegetation map + Drainage map + Geomorphic map + Slope map + Geologic map Basis for the rating of susceptibilities to landslides: Presence of active and/ Presence of numerous and or recent landslides large tension cracks Brgy. Oslao, San Francisco, Surigao Del Norte Areas with drainages that are prone to landslides damming Areas with steep slopes Brgy. Malangza, Igbaras, Iloilo Liloan Actual investigation of actual flood extent and site interview on flood prone areas STANDARD FIELD DATA SHEET Generation of geohazards map (1:50,000 scale) HIGH LANDSLIDE SUSCEPTIBILITY POSSIBLE ACCUMULATION ZONE areas likely to be affected by MODERATE LANDSLIDE SUSCEPTIBILITY transported landslide materials LOW LANDSIDE SUSCEPTIBILITY Detailed Geohazards Assessment and Mapping at 1:10,000 scale (2011-2014) • More detailed geohazards mapping for highly critical areas. • Complimented by an early warning through workshops with critical communities and piloting of installation of landslide warning signages • Issued direct advisories to LGUs particularly prior to arrival of typhoons (e.g. TS Chedeng, Juaning) SAMPLE MAPSJANIUAY, ILOILO SAMPLE MAPSMAASIN, ILOILO Beyond Mapping: Getting people involved Direct advisories on geohazard threats issued to cities/municipalities and barangays for critical areas, right after the field survey Provision of geohazard maps and advisories to concerned LGUs previously identified as prone to geohazards Making people aware through IEC • Conduct of province- and municipal-wide information and awareness campaign • Distribution of IEC materials on geohazards (posters, flyers, comics,videos) TAPATAN, DILG - 2012 HLURB Seminars In partnership with the Office of the Civil Defense (OCD), Region 6 Geohazard Presentation for the LCEs-Province of Iloilo, March 9, 2012 Ombudsman Caravan of Services in Carles, Iloilo. August 29, 2013. MGB-6 posters distribution (landslides and flooding). ABS-CBN – Iloilo interviews RD Juguan October 14, 2013 Re: Landslide in Igbaras, Iloilo Publication of geohazard maps on landslides and floods thru the internet (http://www.mgb.gov.ph) Coordination /meetings with LGUs SB session Barotac Viejo, Iloilo, August 27, 2013. SB San Dionisio, Iloilo, October 7, 2013. Installation of landslide warning signage Before After DENR-MGB Landslide Warning Signage MGB 2008 Little Kibungan Village in Barangay Puguis, La Trinidad, Benguet . Effects on slopes viewed looking westward BEFORE and AFTER Typhoon Pepeng. OTHER GEOLOGIC HAZARDS SINKHOLES What is a “Sinkhole”? A sinkhole is an area of ground that has no natural external surface drainage; Sinkhole in La Salvacion, Carmen, Bohol when it rains, all of the water stays inside the sinkhole and typically drains into the sub surface. Limestone terrain with caves, sinkholes, and solution pipes. Source: (Geoscience Australia) Sinkholes are common in limestone areas. The land usually stays intact for a while until the underground spaces just get too big. If there is not enough support for the land above the spaces then a sudden collapse of the land surface can occur. A sinkhole collapse in an undeveloped area. (Photo Credit: Center for Cave and Karst Studies/Western Kentucky University) A collapsed sinkhole in a parking lot of a mall in the U.S. (Photo Credit: Center for Cave and Karst Studies/Western Kentucky University) Brgy. Oringao, Kabankalan City, Negros Occidental • EARTHQUAKES- shaking of the Earth’s surface caused by rapid movement of the Earth’s rocky outer layer; • Elastic Rebound Theory-if fault surfaces do not slip easily past one another, energy can be stored in elastically deformed bodies of rock. When the fault finally does slip, the elastically strained bodies of rock rebound to their original shapes; • Occurs at a rate of several hundred per day worldwide; • Significant earthquakes in Panay Island - earthquakes in Negros Occidental, Iloilo and Antique last July 2011) Epicenter of earthquakes in the Philippines EARTHQUAKE- RELATED HAZARDS Buildings tilted in liquefied sand due to 1964 Niigata, Japan quake Karl V. Steinbrugge Collection, Earthquake Engineering Research Center, University of California, Berkeley. GROUND SHAKING/ACCELERATION Baguio Park Hotel Residential Bldg. Umingan, Pangasinan Central Luzon State University Library San Jose, N. Ecija GROUND/ SURFACE