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Discovering the World’s Largest Caldera: An Interview with Geophysicist Jenny Anne Barretto - Part 2
by Marcelle P. Villegas - April 01, 2021
“I always say that you don’t have to be a genius or a math wizard to pursue a career in STEM [Science, Technology, Engineering, Mathematics]. It may mean working harder, but your love for learning and discovery will sustain you. Never stop being curious and take every opportunity to learn.” (Jenny Anne Barretto)
Last year, Philippine Resources Journal interviewed geologist and marine geophysicist Jenny Anne Barretto during an online talk show and forum in New Zealand titled “NetKapihan”. She shared the story on how she and her team discovered the world’s largest caldera located in Benham Rise (also known as Philippine Rise) – the Apolaki Caldera.
Ms Barretto is a Filipina scientist who works in GNS Science in New Zealand. She graduated with a degree in MSc Geology from the National Institute of Geological Science in University of the Philippines (UP). She was also an instructor in UP for five years.
Since 2007, she has been assisting coastal States like the Philippines and the Sultanate Republic of Oman in delineating their continental shelves as defined in UNCLOS Article 76. Ms Barretto was a key scientist of the technical working group that successfully confirmed the continental shelf of the Philippines in the Benham Rise region.
In 2019, Ms Barretto and two colleagues, Ray Wood and John Milsom, published a paper in Marine Geology Journal titled, “Benham Rise unveiled: Morphology and structure of an Eocene large igneous province in the West Philippine Basin”. In this paper, they reported the discovery of what may be the largest caldera in the world. They named this the Apolaki Caldera, a tribute to the "god of sun and war" in Philippine mythology. How big is this caldera? It has a diameter of ~150 km, which is 90 km bigger than the Yellowstone Caldera in Wyoming, U.S.A.
“My co-authors and I were part of the Benham Rise continental shelf technical working group. Back in 2008, we only analysed the bathymetric, geological and geophysical data for the purpose of proving that Benham Rise is part of the Philippine continental shelf. That is by showing that Benham Rise is physically connected to Luzon,” Ms Barretto said.
On Part 1 of our interview, she also discussed the possible mineral resources available in the area. “With the presence of the caldera, exploration geologists will say that the possible mineral resources are volcanogenic massive sulfide (VMS) deposits which are significant sources of metals (largely Cu, Zn, Pb ± Au).”
She also noted, “The available data supports our interpretation of the existence of the caldera. However, it is not impossible that other scientists or even us (me and my co-authors) may find later evidence refuting it. It’s just how science works.”
For part 2 of this interview, we shall discuss further the features of the Apolaki Caldera, its origins and possible dangers it might pose future. We also asked Ms Barretto about the difference between working as a scientist here in the Philippines and abroad, plus her message for young people who aspire to pursue a career in science.
PRJ: Bathymetric surveys were used to identify the morphology of the caldera. What other data sets (such as seismic or gravimetric surveys) are available to model not only the surface but also the structure of the caldera?
Ms Barretto: Yes, multibeam bathymetry data was the primary data used that led to the identification of the caldera. There is only one existing multichannel seismic reflection profile that crossed the caldera from which we identified ~1km of sediment fill, which is unusual for oceanic plateaus because these submarine features are commonly blanketed by thin sediments. Single channel seismic reflection profiles across Benham Rise show less than 500 m sediment blanket which is supported by drill cores from DSDP Site 292. There was also a 2D gravity model which included a thick pocket of sediments in the same location as that depicted on the seismic profile.
I went through all the data we have from 2008 and availed of other data in the public domain. Reading John Milsom’s previous interpretations of seismic and gravity data in Benham Rise, I realized that a way to explain the relatively thick pocket of sediments on the summit that he pointed out was the presence of a caldera. So that began our work together to prove or disprove the presence of a giant caldera on Benham Rise.
The seismic interpretation and gravity model were made years before we noticed the caldera feature. The presence of the caldera gave sense to the existence of the thick pocket of sediments.
Future work should include deep penetrating 2D multichannel seismic reflection survey complemented by gravity and magnetic studies would help verify the existence of the caldera and associated structures and could also provide insight into magma chamber dimension and geometry. And of course, ultimately drilling within the caldera feature to get rock samples.
PRJ: Apolaki Caldera would be far the largest caldera in the world with 150 km diameter. Circular morphological structures of that size are known from impacts of meteors. Hence, could this not be a large impact structure?
Ms Barretto: Yes, that’s a possibility that’s why in our paper we compared Apolaki’s morphology with both impact craters and known giant calderas. Results of that comparison exercise show that Apolaki exhibit more caldera-like features than impact crater-like features.
PRJ: Such a huge caldera requires a similarly large magma-chamber or call it a huge “hot-spot”. Hot spots in the earth mantle are relatively stable but the earth crust is moving over such a hot-spot and creates a chain of volcanoes (see Hawaii island chain). In the case of Apolaki, the crust was not moving over the hot spot and volcanic activities occurred at stable positions. Could that not be an indication that the volcanic activity was much smaller without forming a caldera? Hence, the structure might be caused by an impact?
Ms Barretto: Yes, huge calderas imply an underlying equally sized magma chamber. In our paper, we suggested that the formation of the Apolaki Caldera (the collapse) may not have been simply caused by magma withdrawal from its magma chamber. Pre-existing large scale structures (i.e. faults and rifts) related to seafloor spreading and rifting most likely facilitated the collapse.
The lithosphere on which Benham Rise (and of course, Apolaki Caldera) was moving over a hot spot. The mantle plume or hot spot supplying the magma chamber that formed Apolaki Caldera is believed (by scientists who have worked in the region) to coincide with a spreading ridge (the now extinct Central Basin Spreading Center). So as spreading was occurring, the lithospheric plates on either side of the spreading ridge were moving away from the ridge. At the same time, the mantle plume underneath was supplying magma in excess of what the spreading ridge would normally produce and therefore create a chain of oceanic plateaus. Each oceanic plateau is split as the lithospheric plates moved away from the spreading ridge creating paired plateaus on either side, like twins. Urdaneta Plateau is interpreted by many ay Benham Rise’s twin. They are equidistant from the Central Basin Spreading Center and have similar ages. Oki-Daito Rise is an older oceanic plateau on the Urdaneta Plateau’s side. It was hypothesized by Ishizuka et al. (2013) that its twin which is supposed to be on Benham Rise’s side has either subducted or accreted with the Philippines.
PRJ: Do you think the presence of the Apolaki Caldera will put the Filipino fishermen in danger in the future?
Ms Barretto: No. Available data show that volcanism ended on Benham Rise (including its spurs) about 26 million years ago. Threat of a volcanic eruption in that area is very low.
PRJ: What are your future projects or current endeavours with regards to marine geophysics and geology?
Ms Barretto: For New Zealand, I’m currently involved in a research programme looking at next generation geothermal resources. I help put together available magnetic data for the Taupo Volcanic Zone which will help find deeper geothermal energy sources.
I’m also leading a science education outreach project funded by the NZ government. My team and I will bring an augmented reality sandbox in different remote North Island primary schools teaching students about land and water interaction.
For the Philippines, I’m currently doing research with John Milsom and Ronaldo Gatchalian of NAMRIA about the gravity variations over the Zambales Ophiolite. There’s also ongoing work to explain the Luzon syntaxis (the bent shape of Luzon).
There’s more work to be done on Benham Rise, but at the moment we are unable to find funds to do them.
PRJ: What are some of the challenges or difficulties you have experienced as a geologist/marine geophysicist in the Philippines? How does it compare pursuing this career in New Zealand?
Ms Barretto: Funding for research is always a challenge for scientists anywhere in the world, but more so in developing countries like the Philippines. Like anywhere, we scientists in NZ need to write proposals and compete for government funding. However, there is more funding for research available here in NZ than in the Philippines. There is more support for scientists.
Working in NZ is also more relaxed with no need to beat the traffic to and from work. Even if government pay in NZ is less compared to industry, it is still enough to have a decent living. Back in PH, I have to do consultancy work in addition to my teaching job at UP to make ends meet.
PRJ: For the young people, what message would you like to impart to them that would encourage them to pursue a career in geology or in any field in science?
Ms Barretto: I always say that you don’t have to be a genius or a math wizard to pursue a career in STEM [Science, Technology, Engineering, Mathematics]. It may mean working harder, but your love for learning and discovery will sustain you. Never stop being curious and take every opportunity to learn.
Thank you, Ms Jenny Anne Barretto for sharing your amazing story, and GNS Science for the opportunity to write about this discovery and study. Thank you, Sir Rene Molina and NetKapihan for inviting me as panelist in your radio show in New Zealand. PRJ would also like to thank Dr Friedrich Bandelow for his contribution in the technical discussion in the interview, and science journalist Angelica Yang for guidance and support.
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Abe Almirol - June 23, 2021
Cagayan River Rehabilitation: Initiatives from Ridge to Reef
After two severe weather disturbances that took place in the first half of November 2020 heavily hit eight regions in the Philippines, Pres. Rodrigo Duterte immediately signed Executive Order No. 120 creating the Task Force Build Back Better (TF-BBB) to initiate a comprehensive and integrated recovery. Cagayan and Marikina valleys suffered the heaviest damage and human casualties as floods and its aftermath landslides placed many parts of the country in a state of calamity for weeks. Typhoon Rolly (international name: Goni) made its landfall on 1 November 2020 and several days after its onslaught and in almost the same path, Typhoon Ulysses (international name: Vamco) carried with it heavy rains as it reached the Philippine shorelines on 11 November 2020. Tuguegarao and Marikina cities were in deep floods as Ulysses traversed the Philippine area of responsibility. The National Disaster Risk Reduction Management Council reported over 2.3 million people affected across eight regions in the country. Reports indicated that 23,089 individuals displaced were moved to evacuation centres while 46,987 individuals displaced stayed outside evacuation centres. The death toll from Ulysses has reached more than 70. It has severely damaged property and infrastructure in some areas. Videos circulating in social media showed floods reaching the roofs in some parts of Cagayan and Marikina City. Two agencies, the Department of Environment and Natural Resources (DENR) and the Department of Public Works and Highways (DPWH), were given the lead role in a task force working on an operational mode adopting the “whole-of-society approach”. All government agencies and instrumentalities were mandated by EO 120 to take part. After eight months of work, the TF-BBB has made significant gains in pursuing rehabilitation and post-recovery initiatives. DENR has realised that problems such as this needs to consider all factors affecting the whole watershed catchment basin where floods occur. Environmental advocates and experts often refer to this approach as the ridge-to-reef initiative. "In the months since we set out to work in November last year, we have now set into motion significant post-disaster recovery initiatives in three priority geographic areas involving the restoration of Cagayan, Marikina, and Bicol River basins," DENR Secretary and TF-BBB chair Roy A. Cimatu said. Cagayan River Dredging: Agencies in Action Cimatu and TF-BBB co-chairperson Secretary Mark A. Villar of the Department of Public Works and Highways (DPWH) led the ceremonial dredging of sandbars along Cagayan River’s constricted midstream and planting of Bamboo seedlings on the riverbank of Barangay Bangag in the town of Lal-lo, Cagayan last 2 February 2021. After removing the sandbar obstacles that impede water from flowing freely, the roots of planted Bamboos should serve as a soil binder to keep the riverbank intact in the future. There are three priority sandbars to remove near the Magapit bridge, measuring about 235 hectares with an estimated volume of seven million cubic meters, according to TF-BBB statements captured by the media. The first phase of DPWH dredging operations targeted this choke point which a past study identified as the cause of flooding in Tuguegarao City and other settlements near the riverbanks. TF-BBB in Region 2 is chaired by Regional Executive Director Gwendolyn Bambalan of the DENR and co-chaired by Regional Director Loreta Malaluan of the DPWH. In her message during one of the virtual sessions of the task force, Director Bambalan lauded the different government agencies for their support to the Build Back Better initiatives in the region. "The regional TF-BBB is not only addressing the protection and conservation of the environment but also the welfare of barangays and families affected by the restoration of the Cagayan River," Director Bambalan said. In that meeting, the DPWH discussed the dredging operation and riverbank protections works. The Department of Human Settlement and Urban Development gave an update on the status of resettlement projects while the Office of Civil Defence reviewed the improvement of systems and essential services. The Department of Trade and Industry also presented its accomplishments on livelihood projects. For its part, the Department of the Interior and Local Government presented its agenda for strengthened governance and mainstreaming of disaster-risk reduction and climate change action. Representatives of the Land Registration Authority also attended the meeting. The LRA will be the partner agency of the DENR for the easement recovery along the Cagayan River. The Technical Education and Skills Development Authority (TESDA) has trained residents who were eventually hired as laborers and equipment operators to help carry out the dredging operations. TF-BBB has also engaged the Department of Labour and Employment (DOLE) to provide employment assistance to 120 residents for the planting and nurturing of bamboo trees in Tuguegarao City and the towns of Alcala, Enrile, and Gattaran. This will be implemented through DOLE's "Tulong Panghanapbuhay sa Ating Disadvantaged/Displaced Workers" or TUPAD program. Magat Dam blamed In many reports published and echoed in mainstream media and social media, the opening of the Magat Dam floodgates was blamed as the cause of flooding. The National Irrigation Administration (NIA) came out with a fact check to clear its liability. Even the Senate initiated moved to investigate the matter. NIA’s acting department manager of Public Affairs and Information Office, Eden Victoria Selva, came up with a comprehensive technical response, explaining that the Magat river is just one of the many river systems draining to the Cagayan River. “It is noted that the carrying capacity of the Cagayan River is 25,400 m3/s while the maximum volume of water released from the Magat Dam is only 6,706 m3/s indicating that water discharge of Magat Dam due to Typhoon Ulysses is not the main cause of massive flooding in the provinces of Isabela and Cagayan,” Selva said in an article that appeared in INQUIRER.net on 10 June 2021. The controversial statements blaming the Magat Dam’s release of water also aroused public perception that points responsibility to the occupants of watershed areas in the upstream of Magat River. Those affected by the floods were quick to call for punitive actions against watershed occupants, including calls to ban mining in the province of Nueva Vizcaya, including those issued with legitimate permits to operate. Sharing the Burden of Watershed Restoration and Protection In the watersheds upstream of the Magat River, a 10-year project co-funded by the Republic of the Philippines and the Japan International Cooperation Agency is nearing completion. It is called the Forestland Management Project (FMP), a sequel of the several forestry sector projects implemented by the DENR’s Forest Management Bureau in the last 30 years. FMP is a holistic approach in Community Based Forest Management Agreement (CBFMA) areas in sub-watersheds in the upper areas of the Cagayan River, particular the provinces of Nueva Vizcaya, Ifugao and Quirino. FMP is also present in the Upper Pampanga River in Nueva Ecija and in Jalaur River in Iloilo. Anselmo Cabrera, an Institutional Development Specialist working at the Central Project Management Office of the FMP at the DENR Central Office, has proposed a cost sharing mechanism that Watershed Management Councils should develop for mainstreaming. He said there must be a system where every citizen or institution using water can pay for environmental services performed by duty-bearers protecting and maintaining watersheds. Through a cost sharing mechanism, communities living in critical watershed areas will be compensated for their efforts to ensure there is sufficient forest cover. With this scheme, upland farmers could minimize soil erosion by planting permanent crops instead of clearing spots to plant vegetables and other short-term cash crops. The FMP has so far initiated several hundred of hectares planted with coffee, Guyabano, Rambutan, and other fruit bearing trees. About 35 people’s organizations benefitting over 5,000 households, mostly from Kalanguya, Ibaloi, Isinai, Iwak and Ifugao indigenous cultural communities, LGUs were also called to take a more active role in watershed protection. Cabrera welcomes the favourable result of the Mandanas Ruling, where local governments won in getting their share in revenues collected outside the Bureau of Internal Revenue. The Supreme Court has ruled that LGUs can now get a share from the collection of the Bureau of Customs and other national revenues. Information available from the Department of Budget Management (DBM) revealed LGUs, which include provinces, municipalities, and barangays, could get as much as 37% increase in their internal revenue allotments from the national government in 2022. A DBM advisory directed LGUs to use these additional money to fund the full devolution of services, of which, integrated social forestry is one. Nueva Vizcaya Governor Carlos M. Padilla made a friendly overture when nasty comments were posted over social media by angry residents of Tuguegarao City who wallowed in deep floods for several days after Typhoon Ulysses. Some people accused people in Nueva Vizcaya of denuding the watersheds. Relief goods from Nueva Vizcaya were immediately sent in flood-stricken areas, a gesture that Cagayan Governor Manuel Mamba deeply appreciated publicly. He also called for collaboration between people downstream and upstream of the Cagayan River to understand and take actions together. During the last Watershed Management Council meeting, Gov. Padilla reiterated the importance of collaboration and networking to save watershed commons. He recalled a 2018 agreement with stakeholders which includes big water users such as SN Aboitiz and NIA, the two institutions managing the Magat hydropower and irrigation dam in Ramon, Isabela. Also included in the public pledge of support to the 2018 Nueva Vizcaya Declaration on Water are thousands of farmer’s organizations using water resources for irrigation and water utilities, like Solano Water and other entities providing services to majority of urban households. Watershed Management Councils were potent avenues for collaboration in watershed protection and maintenance. In Davao, a bulk water project implemented by Apo Agua Infrastructura, Inc. mentioned in a webinar that the Watershed Management Council has played a crucial role in mobilising communities and people. The TF-BBB in Cagayan Valley experience could be one of the best in the current administration’s whole-of-society approach in big projects. By mobilising both government agencies and communities, it has covered all areas of concern from the top of mountain ridges to the reefs in the sea. It would be exciting to measure if the impacts are indeed better ten years from now.
Philippine Resources - June 22, 2021
DENR studies possible lifting of ban on open-pit mining
The Department of Environment and Natural Resources (DENR) is still studying the possible lifting of the ban on open-pit mining, Malacañang said on Thursday. Presidential Spokesperson Harry Roque clarified that Executive Order No. 130, signed by President Rodrigo Duterte on April 14, does not include a lifting of the ban on open-pit mining. EO 130, which lifts the nine-year moratorium on mineral agreements, is to spur economic growth and support projects and programs of the government. “There is nothing in the executive issuance on mining which is EO No. 130 which lifts the ban on open-pit mining. I have conferred with [DENR] USec. Benny Antiporda and he says the matter is still being studied by the DENR,” Roque said in a Palace press briefing. He, however, reiterated that open-pit mining remains unacceptable for Duterte. In November 2017, Duterte said he agreed with the open-pit mining ban given the environmental damage it causes. Duterte, in his third State-of-the-Nation Address (SONA) on July 23, 2018, also warned the mining industry not to destroy the environment, saying environmental protection is one of his government’s priorities. “To the mining industry, I say this once again and maybe for the last time, do not destroy the environment or compromise our resources; repair what you have mismanaged,” Duterte said. Roque reiterated Duterte’s call to the mining industry to find other ways to extract minerals without destroying the environment. “But I understand from USec. Benny Antiporda that both the President and Secretary [Roy] Cimatu agreed that the mining industry must reinvent mining in a manner that would ensure that it is sustainable and would cost the least damage to the environment,” he added. Open-pit mining is allowed under Philippine law, but Duterte has rejected previous recommendations to lift the ban. The Philippines is the world’s biggest supplier of nickel ore and also among the top producers of copper and gold.
Philippine Resources - June 21, 2021
Villar: Estrella-Pantaleon Bridge On-Track for July 2021 Opening
Photo Credit: Department of Public Works and Highways Public Works and Highways Secretary Mark Villar reassured on Friday, June 18, 2021 that remaining civil works are being fast-tracked to open the new and modernized Estrella-Pantaelon Bridge by next month. “We are here on-site to show you that all substructure and superstructure of the Estrella-Pantaelon Bridge have been constructed and we are confident that we will be able to finish remaining works on approach road and ancillary/miscellaneous works by July 2021,” said Secretary Villar. Secretary Villar together with BCDA President & CEO and Presidential Adviser for Flagship Programs and Projects Secretary Vince Dizon, Transportation Secretary Arthur Tugade and DPWH Undersecretary for Unified Project Management Office (UPMO) Operations Emil K. Sadain inspected the substantially completed Estrella Pantaleon Bridge following an on-site Press Conference on Progress Update of Build, Build, Build Program. Citing a report from Undersecretary Sadain, Secretary Villar noted that the ongoing bridge project across Pasig River linking Estrella Street in Makati City and Barangka Drive in Mandaluyong City is now 93 percent complete. When completed, the new Estrella-Pantaleon Bridge widened from two (2) lanes to four (4) lanes is expected to accommodate as much as 50,000 cars daily, improving traffic situation in the area and decongesting the Epifanio delos Santos Avenue. The bridge-modernization project is implemented by the DPWH-UPMO Roads Management Cluster 1 (Bilateral) and is funded under a Chinese Grant together with Binondo-Intramuros Bridge. Article Courtesy of the Department of Public Works and Highways