This special issue of JDR features 18 papers and reports on an international 2010 to 2015 cooperative project entitled “Enhancement of Earthquake and Volcano Monitoring and Effective Utilization of Disaster Mitigation Information in the Philippines.” This project is being conducted under the SATREPS program (Science and Technology Research Partnership for Sustainable Development), cosponsored by the JST (Japan Science and Technology Agency) and JICA (Japan International Cooperation Agency).
The Philippines is one of the world’s most earthquake and volcano disaster-prone countries because it is located along the active boundary between the Philippine Sea Plate and Eurasian Plate. Collisions by the two plates generate plate subductions and crustal stress that generates earthquakes and volcanic activities on the archipelago.
The Philippines has experienced numerous disastrous earthquakes, the most recent being the 1990 M7.8 Luzon earthquake, which killed over 1,000 local residents. A damaging earthquake also occurred during this 5-year project, in October 2013, on Bohol Island, causing about 200 deaths when houses and other buildings collapsed.
Volcanoes are another major killer in the Philippines. The largest in the last century was when the Taal volcano erupted in 1911, killing 1,300 by a base surge. The 1991 Mt. Pinatubo eruption is known as the largest volcanic event in the 20th century. The Mayon volcano is also known to be a beautiful but dangerous volcano that frequently erupts, causing lahars – steaming moving fluid masses of volcanic debris and water – that damaged villages at the foot of the mountain.
The PHIVOLCS (Philippine Institute of Volcanology and Seismology), a governmental agency mandated to monitor earthquakes and volcanoes, provides earthquake and volcano information and alerts to the public. It also conducts research on the mechanisms behind such natural phenomena and on evaluating such hazards and risks. The PHIVOLCS’s other mission is educating people and society on being prepared for disasters. Earthquake and volcano bulletins and alerts, research output, and educational materials and training provided by PHIVOLCS have enriched knowledge and enhanced measures against disaster.
The primary target of this SATREPS project is to enhance existing monitoring networks, whose equipment has been provided by Japanese ODA (Official Development Aid). Through the SATREPS project, we have introduced the latest technology to provide the public with more accurate information more quickly. This project also promotes research for deepening the understanding of earthquakes and volcano activities in better assessing hazard and risk.
Project components, tasks, and main Japanese organizations are as follows:
1) Earthquake and tsunami monitoring, NIED
1-1) Advanced real-time earthquake source information, Nagoya University
1-2) Real-time seismic intensity network, NIED
1-3) Tsunami monitoring and forecasting, NIED, JMA 2) Evaluation of earthquake generation potential, Kyoto University
2-1) Campaign and continuous GPS observation, Kyoto University, GSI
2-2) Geological and geomorphological studies of earthquake faults, Kyoto University
3) Integrated real-time monitoring of the Taal and Mayon volcanoes, Nagoya University
3-1) Seismic and infrasonic observation, Nagoya University
3-2) Continuous GPS monitoring, Kyoto University
3-3) Electromagnetic monitoring, Tokai University
4) Provision of disaster mitigation information and promotion of utilization, NIED
4-1) Simple seismic diagnosis, NIED
4-2) Tsunami victims interview manga (comic book form) and DVD, NIED
The Philippine Institute of Volcanology and Seismology implements a program on seismic and tsunami network development. It also plans to expand the Philippine seismic network (PSN), commission new stations, rehabilitate and improve existing stations, and repair and maintain the PSN. The PSN consists of 70 stations, 12 of which use broadband seismometers. Stations are strategically located to maximize the use of data from stations. The broadband seismic network is being developed to monitor earthquakes in and around the Philippines and to provide more accurate data for calculating earthquake parameters. Using data obtain from broadband records, the system will immediately calculate earthquake parameters useful for making decisions that provide highly accurate, timely warnings and information. PSN performance is evaluated in this study to ensure this. We consider background noise by analyzing station locations and conditions and their data contribution to SWIFT CMT solutions. We also use power spectral density (PSD) to compare station noise levels to global standards and study data gaps and their causes. Based on the above parameters and using a scale of poor-good-best, the broadband seismic network is currently performing well.
Recently, the Philippine Institute of Volcanology and Seismology (PHIVOLCS) has upgraded its seismic network, equipping it with accelerometers and broadband seismometers for intensity and focal mechanism determinations. As part of this upgrade, PHIVOLCS adapted the use of a source analysis system called SWIFT to determine the centroid moment tensor (SWIFT CMT). SWIFT CMT solutions were estimated for medium to large size earthquakes (4.1 ≤ Mw ≤ 7.6) in the Philippines for the period of January 2012 to November 2013 and were statistically evaluated with respect to the CMT solutions of the Global Centroid Moment Tensor (GCMT) Project. The seismic moments, moment magnitudes, centroid locations, depths and focal mechanisms of most of the SWIFT CMT solutions are found to be consistent to those of the GCMT solutions for earthquakes with Mw ≥ 4.6. The SWIFT system with the new broadband seismographic network provides more CMT solutions for moderate size earthquakes (Mw ≥ 4.1) than GCMT. SWIFT proves to be useful in the development of the Philippines CMT catalogue that will lead to a better understanding of seismotectonics in the Philippines.
A network of 10 satellite-telemetered broadband stations was established under a cooperative project between Japan and the Philippines, and a source analysis system based on waveform inversion of regional seismograms was adapted to operationalize a regional moment tensor analysis of Philippine earthquakes. This study presents the source information generated by the system for recent damaging earthquakes: the Mw6.7 Negros and Mw7.6 offshore Samar in 2012, and the Mw7.2 in Bohol in 2013. Results show that the Negros event was generated by shallow NE–SW thrust faulting with a small strike-slip component, and that the centroid was located slightly offshore. The Samar event occurred in relation to an outer-trench thrust fault within the Philippine Sea Plate, adjacent to a part of the Philippine Trench that has relatively low seismicity. Our centroid moment tensor (CMT) solutions show that the Samar event triggered distinct clusters of outer-rise normal and thrust aftershocks, which we explain as being consistent with a Coulomb stress change in the area. Finally, we infer that the previously unidentified fault zone that generated the Bohol earthquake has a length of ∼100 km, is oriented ENE–WSW, transects parts of Bohol, and extends offshore towards Cebu. These examples show how recent improvements in Philippine earthquake monitoring could contribute to the characterization of earthquake sources and in the understanding of the seismotectonics of the area.
We designed a seismic intensity meter and a data collection network for use in the Philippines. The station unit deployed consists of a digital acceleration sensor with 0.1 gal noise and a compact Microsoft Windows PC. The station unit, which is designed to be installed in local government offices, calculates values every 10 seconds for the PEIS (Philippine Earthquake Intensity Scale), and these values are shown on a display and transmitted to the main PHIVOLCS office over the Internet. One hundred units to be deployed throughout the country are now being distributed to offices.
A network of realtime intensity meters is being established in different parts of the Philippines under a Japan-Philippines cooperation. The intensity meters can record and transmit on a near real-time basis the site-specific levels of groundshaking in terms of macroseismic intensity, peak ground acceleration and peak ground velocity. The intensity meters evaluate earthquake effects using the Philippine earthquake intensity scale – PHIVOLCS Earthquake Intensity Scale (PEIS). Deployment of the instruments was planned according to an optimum distribution with respect to active earthquake generators and vulnerable communities. All manned seismic stations of PHIVOLCS were equipped with an intensity meter while the rest was deployed in relevant disaster risk reduction and management centers. In its initial operation which started in 2012, the network captured several significant earthquakes such as the Mw7.2 in Bohol in 2013.
To enhance the tsunami warning operation system in the Philippines caused by earthquakes in and around the country, staff members of the Japan Meteorological Agency (JMA) joined the SATREPS program in 2012 to help building a tsunami simulation database in the Philippine Institute of Volcanology and Seismology (PHIVOLCS), which stores multiple results of tsunami simulations such as estimated tsunami arrival times and heights at coasts for multiple hypothetical earthquakes of various hypocenter locations and magnitudes. The procedure to construct a database consists of several steps starting from setting assumed fault parameters and others, proceeding to tsunami simulations and data creation to be stored in the database, and as the last step, creating a searching system which picks results from the database according to the location and magnitude of an earthquake. As of July 2014, the PHIVOLCS has stored the results of tsunami simulations conducted for more than 30,000 assumed faults for local tsunamis. The searching system is also prepared which enables to get a quick grasp of expected tsunami features quantitatively. With this database and the searching system, the PHIVOLCS is in near future to issue initial tsunami warnings based on the information of estimated tsunami arrival times and heights immediately after the hypocenter location and magnitude of an earthquake are determined. When the necessary coordination with related organizations as well as the public education for the system and warning messages are ready, the PHIVOLCS will start the enhanced local tsunami warning operation.
We conducted yearly Global Positioning System (GPS) campaigns in the eastern part of Mindanao from March 2010 to March 2014. The obtained station velocities with respect to the Sunda plate (SU) show that WNW motions are dominant due to the convergence of the Philippine Sea plate (PHS). However, it was found that elastic deformations caused by a full coupling of the plate interface down to 80 km could explain a maximum of only 29% of the observed station velocities. In order to interpret the displacement pattern, we applied a rigid block rotation model and determined the Euler vector. As a result, we determined that Mindanao Island could be divided into at least three blocks and that the Philippine fault is one of the block boundaries. Although it was not possible to determine the coupling ratio at the Philippine trench, the dislocation pattern of the Philippine fault showed along-strike variation in Mindanao Island.
We installed three continuous GPS stations on Mindanao Island to provide a basis for enhancing the monitoring of crustal movements. Because there are frequent power outages and Internet connections are slow and unstable in this region, the data acquisition had to be improved by taking necessary hardware and software measures. The cGPS observations have revealed displacements related to plate motions, creep of the Philippine Fault, and a large earthquake. Evaluation of detectability of interplate slip has indicated that our cGPS stations have enhanced the monitoring capability advance from Mw7.2 to Mw6.5 on the coast of northeastern Mindanao.
The 1,250-km-long, NNW-trending, arc-parallel Philippine fault, one of the world’s most active tectonic structures, traverses the Philippine archipelago and has been the source of surface-rupturing earthquakes during the last four centuries. In this paper, we will discuss Philippine fault distribution and segmentation in Mindanao Island by integrating detailed fault mapping together with new geological and paleoseismic data and the analysis of historical surface-rupturing earthquakes. Using geometric segmentation criteria, we have identified nine geometric segments separated by discontinuities such as en echelon steps, bends, changes in strike, gaps, steps and bifurcation in the surface trace. Fault segments ranges from 20 to 100 km in length and are capable of generating earthquakes of Mw6.6 to Mw7.4. The results of our study have important implications for earthquake generation potential and seismic hazard assessment of the Philippine fault in Mindanao Island.
The 1973 Ragay Gulf earthquake produced an onshore surface rupture approximately 30 km in length along the Guinayangan segment of the Philippine fault in southern Luzon Island. Through geologic mapping and paleoseismic trenching, we have characterized the amount of coseismic offsets, the average recurrence interval, and the slip rate of the segment. The coseismic offsets we identified in the field were fairly constant along the fault, ranging from 1 to 2 m. Paleoseismic trenching at the Capuluan Tulon site exposed stratigraphic evidence for three or possibly four surface-rupturing events after the deposition of strata dated at AD 410–535. The average recurrence interval was calculated to be 360–780 years, which is close to that for the Digdig fault, the source fault of the 1990 central Luzon earthquake. The slip rate, based on the calculated recurrence interval and offsets during the 1973 earthquake, has been calculated to be 2.1–4.4 mm/yr. This rate is significantly smaller than the geodetic slip and creep rates of 20–25 mm/yr estimated for the Philippine fault on the islands of Masbate and Leyte. The slip rate deficit may be explained by the possibilities of underestimation of the recurrence interval due to possible missing paleoseismic events within the stratigraphic records, the occurrence of larger earthquakes in the past, and the aseismic fault creep between the surface-rupturing earthquakes.
A 15 km southward offshore extension of the Philippine Fault in the Ragay Gulf near the east coast of the Bondoc Peninsula is recognized and described with 150 newly acquired, high-resolution acoustic reflections. The vertically dipping fault strikes roughly NW-SE and exhibits pressure ridges and depression structures indicative of strike-slip movement. The southern portions of the fault exhibit particularly sharp breaks on the seafloor that were probably produced by the 1973 Ragay Gulf Earthquake. Offsets of distinct acoustic layers are interpreted to indicate the strike-slip fault has slipped in earthquakes at least four, and likely more than 11 times during Holocene.
The electromagnetic (EM) method first applied to monitor the activity of the Taal Volcano from 2005 consists of repeatedly surveying total magnetic intensity (TMF) and continuously measuring EM fields. The EM observation system was greatly improved through the SATREPS project summarized in this paper. The resistivity structure is investigated in the project using the magnetotelluric (MT) method. The MT method revealed a large hydrothermal reservoir just beneath the center of Volcano Island. The existence of this reservoir explains several things – the special features of the devastating 1911 eruption, i.e., that it was magmatic-hydrothermal, together with the geochemical characteristics of Main Crater Lake, especially the absence of SO2 gas. The reservoir’s formation process provides useful suggestions for understanding the volcano’s past eruption cycle.
Determining the location and the amount of volume change of the pressure source beneath a volcano during the eruption preparation stage is an important issue in monitoring the magma accumulation. To do so, we have implemented a GPS campaign survey network around the Mayon volcano and monitored ground deformation since 2005. Rapid ground-deflating deformation was detected accompanied by the 2009 eruption. The Mogi model pressure source was estimated to be 8.5 km deep beneath the summit and the amount of volume change -13 × 106 m3. In magma accumulation preceding the 2009 eruption, ground deformation showed a weak inflationary trend, but it was difficult to evaluate the source parameters definitively. After the 2009 eruption, no deformation has been detected by the Continuous GPS observation network since 2012. Trend of many baselines of continuous and campaign network turned to extension since 2014. Magma may have started accumulating beneath the Mayon volcano.
Most of the human casualties in past earthquakes were attributed to the collapse of buildings, particularly masonry constructions in developing countries. Most of these buildings are categorized into “Non-Engineered Construction.” In effect, these structure are spontaneously and informally constructed in various countries in a traditional manner without any or with little intervention in their design by qualified architects and engineers. Unfortunately, these types of buildings have been extensively constructed in most of the seismic prone areas in developing countries. Therefore, the safety of “Non-Engineered Construction” has become one of the most urgent issues in recent years. The concrete hollow block (CHB) masonry structures have recently become common residential structures in the Philippines. A full-scale shaking table test on CHB masonry structures of Philippine ordinary houses was conducted in Japan. This experiment aims to acquiring a better understanding of the behavior of these structures during major earthquakes, and its results will be used to produce simple seismic evaluation methods as awareness tools, and to disseminate information on safer construction of houses in the Philippines.
The safety of non-engineered construction is an urgent concern, because it is a primary cause of human casualties. The first step in disaster risk reduction is to understand the risk. For earthquake disaster risk reduction, it is critical that the stakeholders, such as government officers, masons, contractors, community leaders, and residents/house owners, understand the earthquake risk, or damage estimate for their houses. To reduce earthquake disaster risks, residents and house owners must understand these risks and take responsibility for necessary actions with technical advice from professionals. Therefore, simple seismic evaluation methods were developed as awareness tools for non-engineered houses in the Philippines.
The end goal of the projects under the Philippine Institute of Volcanology and Seismology – Japan International Cooperation Agency – Japan Science and Technology Agency – Science and Technology Research Partnership for Sustainable Development (PHIVOLCS-JICA-JST-SATREPS) Program on Enhancement of Earthquake and Volcano Monitoring and Effective Utilization of Disaster Mitigation Information in the Philippines is to provide rapid, reliable and usable information on earthquakes, tsunamis, and volcanoes to the public. Component 4 of this program involves the provision of disaster mitigation information and promotion of utilization. Practical tools for the evaluation of vulnerability and safety of houses in the Philippines were developed in this component. Two tools were developed during the project; a 12-point questionnaire for self-check for earthquake safety of concrete hollow block houses in the Philippines (Tool 1) and a software program to evaluate the safety and earthquake vulnerability of houses (Tool 2). These tools aim to raise the awareness of stakeholders such as house owners, local engineers, building officials, and local government units, as well as function as an educational tool for the quick and simple evaluation of the vulnerability and safety of houses. The tools were disseminated to the specific users for enabling the effective utilization of disaster mitigation information. Various strategies were implemented for disseminating these tools: a launch activity was conducted during PHIVOLCS InfoSentro, an activity implemented by PHIVOLCS to update the public on its recent programs, projects, and activities; a copy of Tool 1 was uploaded on the PHIVOLCS website; training modules were developed; and training programs and workshops were conducted for users.
Filipinos who have settled in Japan as residents were interviewed between June to August 2011. The purpose of these interviews was to gather first-hand accounts of survivors about the March 11, 2011, magnitude 9 earthquake that triggered one of the worst tsunami events in Japan’s history. It is important to document what survivors have learned from these events. Considering how infrequently tsunami events occur in the Philippines, lessons from these descriptive narratives could become a valuable information resource for the Philippines population that might experience tsunami-generating earthquakes in the future, especially because first-hand accounts by Filipinos living abroad would be easy for those living in the Philippines to relate to. This documentation has focused on how Filipinos in Japan were affected, what actions they took during the event, their prior knowledge of earthquake and tsunami preparedness, and how they survived and recovered. Important actions highlighting what to do include the following five: (i) attending and taking part in community awareness activities, (ii) preparing emergency bags holding useful items such as flashlights, food and water, and protection against the cold, (iii) using mobile phones, (iv) paying attention to warnings, and (v) relying on multiple information sources such as television, radio, community sirens or public address systems, and local fire units. Although simple, these actions could save lives in critical times. The lessons they teach show what to do and what NOT to do during earthquakes and tsunami warnings. What NOT to do includes the following:
(1) Do NOT panic.
(2) Do NOT return home to pick anyone or anything up, especially if you live near the coast.
People in other countries may benefit from learning about survivors’ experiences of the March 11, 2011 Great East Japan Earthquake and Tsunami. The Philippines has a similar tectonic setting to Japan. The experiences of Filipinos living in Japan during the event were documented in face-to-face interviews conducted three months after the event; data from these interviews were compiled and reviewed. From among the survivors’ experiences, four stories were selected for depiction in manga-style comics, which are popular among young people. Using storyboarding, each of the featured stories was carefully illustrated to present important details that readers could easily understand and relate to.
The purpose of this paper is to analyze the initial reactions of banks with the disaster to improve the resiliency of banking industry and encourage banks to share more disaster related information in the industry to help each other. Two severe cases in the banking industry were picked up, one for the 3/11 Great East Japan Earthquake of 2011 (3/11 or 311) and the other for the 9/11 terrorist attack of 2001 (9/11 or 911). In addition, to support identifying the issues of the banks, this study refers to the case of Otsuchi Town Hall that had serious damages by the 3/11 Great East Japan Earthquake of 2011, as it is difficult making a direct comparison with some points between Iwate Banks and Fuji Bank. Those are analyzed in comparison with the other case of the Otsuchi Town Hall. Those cases are discussed from the various angles such as the immediate tasks they have to perform when disaster happens (the Day Zero Duty), the recovery location strategy, BCM Policy and Crisis leaders. Potential conflicts were found between the BCM policy and the Day Zero Duty as well as the quick decision making and having too many recovery options etc.
In Oct. 2013, one hundred small and medium enterprises (SMEs) were surveyed regarding their business continuity. 70% of the SMEs surveyed had implemented BCP. Our previous paper, “Organizational Promoting Factors for SME BCP,” reviewed the survey results using correlation and path analysis. The review found directives from the president to be the most influential factor of BCP implementation and that there were two different levels of BCP implementation and BCP embedding. Over 60% of the companies that had implemented BCP had had difficulties embedding BCP. Our previous paper identified the BCP environment and its four key component factors, including organizational BCP momentum and company-wide information sharing that would affect BCP embedding, among others. It also identified four key BCP advantages related to normal operations, including enhancing marketing advantage and building employee togetherness, which had a causal relationship with successful cases of BCP embedding. This paper reviews our previous survey results in detail to find key factors separately in tasks and problems as well as in corporate culture groups. It also re-identifies four factors in the tasks and problems group as well as three factors in the corporate culture group. This paper also analyzes the relationships among the perceived BCP advantages to determine if some of them affect the remaining advantages. It finds that organizational strategic risk/BCP mind and employees’ risk mind bring about other BCP advantages, which could be interpreted to mean that two minds, one top-down and one bottom-up, are critical in the BCP embedding stage.