TsunamiTsunami sourcesource mechanismsmechanisms inin thethe PhilippinePhilippine archipelagoarchipelago
Carla B. Dimalanta1, Graciano P. Yumul, Jr.1,2, Edanjarlo J. Marquez3 and Bart Bautista4
1National Institute of Geological Sciences, University of the Philippines, Diliman, Quezon City, Philippines
2Department of Science and Technology, Bicutan, Taguig, Philippines
3Department of Physical Sciences and Mathematics, University of the Philippines-Manila, Philippines
4Philippine Institute of Volcanology and Seismology – Department of Science and Technology, Diliman, Quezon City, Philippines TectonicTectonic settingsetting
~6 mm/yr ~7 mm/yr
~9 mm/yr EarthquakeEarthquake generatorsgenerators East Luzon Trough Manila Trench
P h i l i p p i n e
T r e n ch Negros Trench
ch en C r o T T u t l r a u e S b n a c t h o http://phivolcs.dost.gov.ph TsunamigenicTsunamigenic earthquakesearthquakes
• generatedgenerated byby shallowshallow earthquakesearthquakes • largelarge tsunamistsunamis likelylikely toto bebe generatedgenerated byby earthquakesearthquakes withwith magnitudemagnitude >> 7.07.0
1981-2005
Wong & Chan, 2006 120o 125o
Philippine Sea Tsunami Vulnerability Map
15o
South China Sea
10o
Sulu Sea
Celebes Sea
http://phivolcs.dost.gov.ph 120o 125o
Philippine HIGHER VULNERABILITY Sea
15o
South 9 lack of knowledge China Sea 9 high population density 9 improper land use 10o
Sulu Sea 9 fatalistic attitude
Celebes Sea
http://phivolcs.dost.gov.ph EarthquakesEarthquakes (M(M >> 7.0)7.0)
http://neic.usgs.gov/neis/epic/epic.html Tsunamigenic earthquake events
www.phivolcs.dost.gov.ph 19761976 MoroMoro GulfGulf EarthquakeEarthquake
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Area north of Zamboanga
9Magnitude: 7.9 9Cotabato Trench 9 ~6 m tsunami, peak velocity: 720 km/hr QuickTime?and a TIFF (Uncompressed) decompressor 9Tsunami affected 700 km of the are needed to see this picture. coastline bordering the gulf (Pagadian City, Cotabato City and Zamboanga City) Zamboanga City) Bongo Island www.phivolcs.dost.gov.ph 19901990 BoholBohol EarthquakeEarthquake
9 Magnitude: 6.8 9 Offshore thrust fault, east of Bohol Island 9 0.2-2 m tsunami 9 affected the municipalities of Jagna, Duero, Guindulman, Garcia Hernandez, Valencia as well as Camiguin Island
(Besana et al., 2004) 19921992 EasternEastern MindanaoMindanao EarthquakeEarthquake
9 Magnitude:Magnitude: 6.86.8 9 PhilippinePhilippine TrenchTrench 9 SeveralSeveral cmcm upup toto ~6~6 mm 9 AffectedAffected thethe easterneastern coastlinescoastlines
(Besana et al., 2004) 19941994 MindoroMindoro EarthquakeEarthquake
9 Magnitude: 7.1 9 Aglubang River Fault (dextral) 9 Vertical run-up: 0.5-8.5 m; Horizontal run-up: 4-250 m 9 Tsunami affected 40 km of the northern and eastern shoreline of Mindoro (Puerto Galera to Pinamalayan) plus the Verde and Baco Islands PHIVOLCS Special Report No. 2 TsunamigenicTsunamigenic earthquakeearthquake eventsevents
Date Affected Areas Magnitude November 9, 1828 Manila Bay 6.6 June 3, 1863 Manila Bay 6.5
August 15, 1918 Southern Mindanao 8.0 November 11, 1921 Manay, Davao Oriental 7.5
April 14, 1924 Mati, Davao Oriental 8.3 August 1, 1968 Casiguran Bay 7.3 April 7, 1970 Baler, Aurora 7.0
October 31, 1975 Borongan, Eastern Samar 7.2
July 16, 1990 Luzon 7.8 SummarySummary
9 TsunamisTsunamis inin thethe PhilippinesPhilippines werewere generatedgenerated byby
• TrenchTrench systemssystems surroundingsurrounding thethe archipelagoarchipelago
• FaultsFaults ThankThank you!you!