[Music] d [Music] the Philippines an island AR system located southeast of the Asian land mass is trapped at the margins of the Eurasian Sunderland to the west and the Philippine SE plate on the East the Ignus sedimentary and metamorphic rocks which make up the different islands in the Philippines reflect the complex processes which have occurred at different periods throughout its history and formation comprising of more than 7,500 islands and Island groups the Philippine island arc system was produced by the Collision of geologic blocks the collision and subduction of cestal materials along trenches results in volcanism earthquakes and the implacement of fragments of the crust and upper mantle on land on this figure we see the orange triangles marking the locations of active potentially active and inactive volcanoes the Philippine Institute of volcanology and seismology monitors 23 active volcanoes throughout the country the most active volcanoes are Mayon Tal laon buusan hiok hiok and P the geological configuration of the Philippine island arc system where it is bound on both sides by trenches is the reason why we experience a lot of earthquakes in the country aside from trenches other potential earthquake generators are active faults the most significant of which is the Philippine F Zone this can be traced from the westernmost tip of Theon island in the Ilocos region through V masbate it cuts later into two then goes through Sera and exits in miti davo Oriental because of these earthquake generators the Philippines experiences on the average around 20 earthquakes daily but most of these are hardly felt but are recorded by instruments the different color dots on the map on the right show the location of earthquake epicenters which have been recorded since the 1600s the country has been devastated by several destructive earthquakes with magnitudes between 6.2 and 7.9 this includes the earthquake that took place on August 2 1968 with a magnitude of 7.3 and whose epicenter was located in casiguran keson despite the distance of the earthquake epicenter this was felt strongly in Manila and led to the collapse of the Ruby Tower in b a second devastating earthquake was the one that struck Lon on July 16 1990 with a magnitude of 7.9 its epicenter was located near the town of Ral in WEA but the earthquake was felt in north and Central theone we remember this earthquake due to the devastation that we saw in Bago particularly the collapse of the hayat hotel more recently we witnessed the devastation caused by the magnitude .9 earthquake which struck gulan in Negros Oriental several people died in barang which were buried when the ground shaking triggered landslides a year later on October 15 2013 an earthquake with a 7.2 magnitude struck ball this caused the collapse and destruction of several historical churches such as the Lok church now if we go back to the map that I showed earlier it is worth noting that we do not see any earthquakes recorded in Palawan Island this can be explained by the fact that Palawan Island and several other Islands which are collectively called the Palawan microcontinental block were not originally part of the Philippine island arc system it originated elsewhere before colliding with the rest of the Philippine island arc system which geologists called the Philippine mobile belt the Palawan microcontinental block used to be part of Mainland Asia the evolution of the Philippine island arc system began when this fragment broke off from the southern margin of Mainland Asia the Continental margin became thin and led to the formation of an oceanic crust this thinned margin of the Continental landmass opened up to become the South China Sea continued opening of the South China Sea caused the broken off fragment to drift southeastward and eventually collided with a Philippine mobile belt which was moving northward although this collision between the palawa microcontinental block and the Philippine mobile belt is a wellestablished aspect of the formation of a Philippine island arc system it is important to reexamine this in light of improvements in Technologies and and development of new equipment this may provide new data that will be useful in understanding the evolution of the Philippine island arc system one thing that geologists had to contend with previously was the lack of data on the ages of the Rocks exposed in different parts of the Philippine island arc system new methodologies and access to some laboratory facilities have now provided us with additional hes for some of these rocks we also now have better equipment for determining the compositions of rocks so for more than a decade now we have focused our attention on Central Philippines in order to collect more data that will help us understand this aspect of the evolution of the Philippine Island art system our study has taken us to the romlon island group which is made up of the Blas romblon and siuan Islands geologic mapping and geophysical surveys were carried out along with the collection of rock samples this were brought back to the laboratory for various analysis among the important features observed in the romblon island group are the metamorphic rocks which are characterized by the presence of quartz minerals this quartz-rich metamorphic rocks are believed to have been derived from rocks similar to those found in Continental land masses such as Mainland Asia thus we use this new data as evidence to suggest that the romon island group forms part of the Palawan microcontinental block so together with Palawan they make up the fragments which broke off from the southern margin of Mainland Asia after completing our investigations in the roblon island group our next destination was the Northwestern part of Panay Island particularly the B Wanga Peninsula the results of our field mapping various laboratory analysis and paleontological examination of the roack samples show that the types of rocks exposed in bwanga Peninsula are similar to those found in Palawan and nearby Islands the presence of quartz Greens in the sedimentary rocks is a common feature in the rocks found in banga and palawa as mentioned earlier quartz is a typical component of Rock formed in a continental land mass this new data thus supports earlier models that bwanga Peninsula along with Palawan Island used to be part of Mainland Asia another result generated by our studies is the information provided by fossils in the rocks in bwanga Peninsula we were able to extract Nan of fossils such as the microscopic remains of regian from some of the Rock samples radiolarians are protozoans which produce celicious skeletons that may be preserved in celicious rocks like churs based on the shape skeletal form and symmetry of skeletal spines it is possible to identify their species this is in turn used to determine the age of the Rocks where they were found because certain species flourished only during specific ages or periods within the Earth's history the radial lens extracted from the samples in bwanga Peninsula Northwest panai indicate that these rocks are of Jurassic age around 166 million years ago the rocks in bwanga Peninsula Northwest panai share similar features same rocks similar compositions with those that are exposed in bwanga and Palawan Island a similar Jurassic H is suggested by the larians from the samples although there are some sections of bwanga and Palawan which record even older ages approximately 200 to 207 million years old from this results we provide new evidence to show that bwanga Peninsula is also part of the Palawan microcontinental block from Northwest panai we headed to the next Target of our field campaigns which is mindoro Island previous works by other researchers have presented differing ideas on the island some researchers propose that it is only Southern mindoro which is part of the microcontinental fragment others however argue that it is the entire Island which is of Continental origin with our field campaigns particularly in Northwest midoro we collected rck samples from examination under the microscope the sandstones are dominantly made up of quartz grains the metamorphic rocks also show quartz grains and other minerals which are typically observed in rocks from a continental land mass in addition to the rocks and their composition the fossils obtained from the limestones indicate an age of around 28 to 41 million years although much younger than the ages of obtained for the sedimentary rocks in Palawan and banga Peninsula the sedimentary rocks in indoro are still considerably older than those found in the Philippine mobile belt aside from fossils we can also use zircons to determine the ages of rocks ziron is a mineral found in Ignus sedimentary and metamorphic rocks it is resistant to heat and corrosion and can be preserved in rocks despite the changes which rocks May undergo zircons are thus useful in determining the ages of rocks which contain them in the case of a Sandstone sample from Northwest mindoro the ziron recorded ages of approximately 18 185 to 196 million years old this means that the Sandstone contains fragments of old rocks and when compared with rocks from other areas these ages are similar to the ages of rocks from the southern part of Mainland Asia with this results we propos that the whole mindoro island is also part of the Palawan microcontinental block for our next investigation we decided to go towards the Eastern side of central Philippines particularly masbate Island we did field and other surveys to see if we will see any similarities between the rocks in mbati Island with the rocks that we saw in the areas which we previously investigated when the mbat sandstones were examined under the microscope we did not see the quartz grain which were dominantly observed in the Sandstone samples from Palawan banga and mindoro the fossils extracted from some of the mbata sedimentary rocks corresponded to an early to Middle myosin age which is around 23 to 11.6 million years these are younger than the rocks in mindoro and much younger than the old rocks in Palawan and bwanga because of the different ages and types of rocks exposed in mbati Island we were able to conclude that mbat Island does not form part of the Palawan microcontinental block although earlier Studies have previously described the Palawan microcontinental block we have provided a additional data and new evidence from our recent field campaigns to show that in addition to Palawan and bwanga the roblon island group mindoro and banga Peninsula comprise the Palawan microcontinental Block in summary we look at different aspects and employ various methodologies in order to constrain the formation of the Philippine Island artart system however further studies must still be conducted for us to refine our understanding of how the Philippines was formed looking back to its geologic history and the processes that contributed to its formation can also provide insights on the nature of the different U hazards in the country [Music] [Music] [Applause] [Music] [Music] [Music]