Consolidated Report of Initial Response of the UP System QRT to Localities Impacted by the July 27 M7.0 Abra Earthquake
The University of the Philippines has once again mobilized the university’s resources to provide aid to Filipinos affected by the devastating M7.0 earthquake. This comes on the heels of two recent disasters, Typhoon Odette in December 2021 which devastated Surigao, Cebu, and Bohol, and Tropical Storm Agaton in April, which impacted multiple barangays in Leyte. UP provided shelter tents for families who lost their houses in Limasawa, Cebu and Pitogo, Bohol in January 2022 (Figure 1). A week ago, a UP Team composed of faculty members and researchers from the UP Resilience Institute and UP Tacloban conducted field surveys in barangays Pilar and Malaguicay in Abuyog, Leyte, communities overwhelmed by a landslide-tsunami (Figure 2) during the height of tropical depression Agaton. While in the area, they also provided advice to Barangay leaders on how to monitor potential landslides that may affect their community.
Figure 1. Shelter tents donated to families affected by the strong winds of Typhoon Odette
Figure 2. Debris field of a coastal community overwhelmed by a landslide tsunami.
As initial steps for efforts to help victims of the Abra earthquake, Dr. Mario Aurelio of the UP National Institute of Geological Sciences is currently en route to Abra as the advance party of the University to locate the faults where the M7.0 earthquake occurred and document its impacts. The UP Resilience Institute – Institution Building Office has also been tasked to conduct initial reconnaissance in affected communities and will prepare an initial assessment. A team from the UP Manila Philippine General Hospital and UP Pahinungod lead by Dr. Eric Talens is also currently coordinating a mission to respond to the medical needs of affected populations in Abra. UP organizations such as Sama-Sama Tulong-Tulong, UP Vanguard, and NoWhereToGoButUP are also working hand-in-hand to provide much needed aid and relief to our countrymen. To harmonize these efforts, UP, through former Regent Spocky Farolan, has been closely coordinating with the provincial government of Abra to assess the immediate needs of communities.
Geological Assessment
Seismotectonics – Earthquake Data Analysis
As of this writing, the Philippine Institute of Volcanology and Seismology (PHIVOLCS) plots the epicenter of the main shock at 17.5° N latitude, 120.6° E Longitude, or around 7 km northeast of the capital of Abra, Bangued. The depth of focus is 15 kilometers. (Figure 3). Since the main shock, more than two thousand aftershocks have been recorded, with felt aftershocks averaging about 6 per day (based on onsite experience of the QRT). The strongest recorded aftershock so far is magnitude 5.1. About 28 more with magnitude 4 or greater have so far been recorded (Table 1).
The main shock shows a compressional focal mechanism solution (FMS), consisting of two reverse faults: one striking 233°, dipping 69° and a rake of 109°, the other at 8°, 28° and 49° respectively. One of these faults caused the earthquake and should be manifested in the form of a ground surface rupture (GSR) theoretically. One of the objectives of the preliminary field assessment was to search for the surface manifestation of the GSR. So far, the advance UP QRT has not found the GSR. Initially, PHIVOLCS has identified the Abra River Fault as the structure responsible for the earthquake. However, this has not been substantiated by a GSR.
Figure 3. Debris field of a coastal community overwhelmed by a landslide
tsunami Seismotectonic map (top) and section (bottom) of the M7.0 27 July 2022
earthquake of Abra. Shown are focal mechanism solutions (FMS) of main shock and
available aftershocks, and aftershock distribution of seismic events with magnitudes
M4.0 or greater.
To guide in the continued search for the GSR, the geometry and mechanics (i.e., sense of movement) of the earthquake-generating fault can be analyzed using aftershock data. Four aftershocks so far have provided sufficient data to produce FMSs. Three of these aftershocks indicate fault parameters similar to those of the main shock (i.e., compressional thrust fault pair) while another shows a strike-slip fault pair (Figure 3). The plot of aftershocks of magnitude 4 or greater suggests an earthquake-generating fault plane that dips gently to moderately (~28°) to the east-southeast. This implies that the GSR, if it has reached the surface, should be located west of the main shock, in the province of Ilocos Sur, particularly in the municipalities of Narvacan and Santa, and San Quintin in Abra.
Table 1. Earthquake data of events plotted in Figure 1.
Ground Deformation
Most manifestations of ground deformation due to the earthquake in the areas investigated are in the form of landslides. These are most prominent along roadcuts in mountainous areas such as in Licuan-Baay and Malibcong (Figure 4). A major landslide has been reported by PHIVOLCS in Dolores, Abra. A minor site of liquefaction was observed in Brgy. Palao, Bangued. More prominent sites of liquefaction have been reported in Vigan and Santa, Ilocos Sur and in Dolores, Abra.
Figure 4. Landslides along the national road between the municipalities of
Licuan-Baay and Malibcong, Abra.
Impact Assessment
Damages to Infrastructure
As reported by Dr. Mario Aurelio, it is likely that liquefaction contributed significantly to the damage of infrastructure in Vigan and Caoayan as these areas are founded on river delta deposits of the Abra River. In the mountainous areas, intense ground shaking is likely the major factor in infrastructure damage. Infrastructure damage is mostly in the form of collapsed buildings, fallen perimeter walls, cracked floors, cracked and fallen walls and beams of houses. In Bangued, notable damage includes collapsed 3 to 4 storey buildings (Figure 5). Several of these collapsed multi-storey commercial and residential buildings are located at or near rice fields. Those located on rice fields are often constructed over a back-filled foundation. Houses of more well-to-do families incurred significant loses on broken ceramic furniture, china and chandeliers.. In more remote areas, such as in barangays of Tayum, Lagangilang, Sallapadan and Licuan-Baay, poorly built (i.e., houses with insufficient structural components, such as lacking posts, beams, rebars, etc.) houses have sustained significant damage (Figure 6). On July 31, 2022, the Provincial Disaster Risk Reduction and Management Council (PDRRMC) of Abra reported the that 250 Houses where completely destroyed while 17,920 were partially damaged. The PDRRMC reported that the estimated cost of these damages is ₱409,592,719.
Figure 5. Collapsed multi-storey commercial and residential buildings in Bangued,
Abra.
Figure 6. Damage sustained by houses constructed without proper structural design
in Bangued (top), Tayum (bottom right) and Sallapadan (bottom right and middle),
Abra
The sections of the national road in Brgy. Garreta, Pidigan and Brgy. Palao, Bangued are affected by buckling (Figure 7).
Figure 7. Sections of the national road in Brgy. Palao, Bangued (top) and Brgy.
Garreta, Pidigan (bottom), Abra, affected by buckling.
The PDRRMC of Abra estimates the total damages to infrastructure to be ₱793,115, 223. Estimates of damages to agricultural infrastructures were separately pegged at ₱6,277,950.00 while damages to agricultural lands are assumed to amount to ₱11,950,417.00. The Provincial Capital of Abra also identified the total cost of damage to agricultural produce as being ₱26,301,617.
Heritage and cultural monuments were also severely affected by the earthquakes and restoration work is necessary to return them to their original form and function (Figure 8).
Cultural monuments in Ilocos Sur such as the Bantay Tower, St Peter and St. Paul Parish, and the Metropolitan Cathedral of the Conversion of St. Paul the Apostle in Vigan sustained structural damages that rendered the stone-based structures unfit to be used unless structural repairs and rehabilitation are done. In Vigan, many Spanish stone-based heritage houses were also badly hit.
In Abra, the Santa Catalina de Alejandria Parish Church in Tayum, declared in 2001 as a National Heritage Treasure, and San Ruiz Church in Benqued were heavily damaged as well. Condemned buildings, especially in Abra, are at risk of collapsing and pose an imminent danger to those living within the vicinity.
Figure 8. Damaged churches in Bantay, Ilocos Sur (top), Caoayan, Ilocos Sur
(bottom right) and Tayum, Abra (bottom left).
The UP Diliman Institute of Civil Engineering composed of 7 faculty and research staff headed by Dr. Harold Aquino was also deployed to conducted non-destructive testing for structural integrity of historical sites in Vigan (Figure 9). It is their intention to also visit Abra and test more buildings that were affected by the M7.0 temblor.
Figure 9. Team from UP Diliman Institute of Civil Engineering conducting
non-destructive structural integrity testing on damaged heritage sites in Vigan, Ilocos
Sur.
Status of Affected Population
The earthquake claimed the lives of five people and injured 231.
Although water was available, potability was not good. Most residents whose houses have been damaged still opt to stay outdoors, usually in tents (Figure 10), for fear of collapse of their houses given the continued aftershocks. There still are no clear instructions from authorities on whether they can already return safely to their dwellings. Some residents also show signs of anxiety partly as a result of the absence of clear instructions. Most residents in far-flung villages also need financial and logistical assistance.
As of August 1, the municipality of Bucloc had yet to receive relief and medical assistance from the provincial disaster response operations despite damage to the area being reported as severe.
Figure 10. Residents of affected areas camping out for fear of collapse of their
already weakened houses as aftershocks continue.
Response by UP System Pahinungod
The response activity was a unified operation coordinated by the Ugnayan ng Pahinungod system office led by Dr. Eric Talens. The Pahinungod offices of UP Manila, UP Diliman, and UP Baguio, together with the Abra Medical Society, planned the quick mission to barangays, Lingey and Lamao, Abra. The mission set out with the following objectives:
– Deliver relief, and water filtration systems to the municipality of Bucloc, Abra
– Conduct medical consultations and psychological first aid (PFA)
– Assess for further needs that UP may be able to provide
Volunteers from UP Manila and UP Dilimandeparted from MetroManila with the cargo truck on August 1, 2022, rendezvoused with the contingent from UP Baguio in San Juan, La Union; and then proceeded to Bangued, Abra, guided by information from local contacts. The slow trek to Bucloc took 3 hours over mountainous roads with occasional passageways only recently cleared of landslide debris. The team met with Mayor Gody Cardenas of Bucloc, before proceeding to the target barangays. UP Manila volunteers distributed the family relief packs, water filtration systems, hygiene kits and sleeping mats. UP Diliman and UP Baguio volunteers provided Psychological First Aid (PFA) to the children in the evacuation areas. The Abra Medical Society volunteers and some volunteers from UP Manila conducted medical consultations and dispensed needed medications. Brief meetings were also conducted with the local officials as well as the local health workers in both barangays.
The team was in Brgy. Lingey on Day 1 of the activity (Aug 2, 2022). On Day 1, 166 family relief packs, 4 water filtration systems (turned over to the municipal representative, one for each barangay), and 120 Kiddie packs were distributed. 450 bowls of hot macaroni soup, prepared at the site by a private donor, Mr. Oscar Alfonso, were also given away in this barangay. PFA was conducted to the 120 children.
Day 2 found the team in Brgy, Lamao, doing the same distribution of work. 154 family relief packs were distributed. PFA and Kiddie packs were given to 80 children. Again 450 bowls of hot macaroni soup were served.
The mission volunteers were back in their respective CU’s by the early morning of August 3, 2022.
A total of 200 family packs were distributed by UP Manila.
Other Actions Taken
The UP NOAH Center is also leading in processing and analyzing satellite imagery of all affected localities. 100 family dome tents constituting humanitarian aid donated to the UP Resilience Institute by SOS Attitude France in partnership with Rotary Philippines will be deployed to localities where they are most needed upon their arrival from Europe.
Each time there is a disaster, the University of the Philippines System endeavors to help communities in affected areas. Apart from the most recent quake in Abra, the UP System has responded to the following disasters since 2018:
I. Naga Landslide (September 20, 2018)
A. Quick Response team deployment
B. Map of buried houses using available pre- and post-disaster maps (LiDAR, iFSAR, OpenstreetMap building footprint data)
C. Longer term assistance (CLUP, CDRA, LDRRMP)
D. Journal article published in Frontiers for future reference
II. Tropical Storm Usman (2018)
A. Deployment of tents in lahar stricken areas
B. Donation of 3 seismometers to Tabaco, Daraga and Guinobatan
III. Zambales earthquake (April 22, 2019 )
A. Quick response team deployment
B. Assistance to Mayor Michael Galang of Floridablanca
C. Participatory Planning of a Resettlement Community: Aeta Community of Barangay Diaz, Porac, Pampanga
D. Participatory training and workshops facilitated by three institutions in accordance with their fields of specializations. Drone mapping of earthquake structures
E. Journal article published in Geoscience Letter for future reference
IV. Mindanao earthquake (October 16, 29, 31 and December 15, 2019)
A. Medical Teams deployed
B. Donation of relief goods
C. Quick Response Team coordinated w/ Provincial Government (Vice Governor Shirlyn Macasarte)
D. Deployment of Shelter Tents in Batangas and Laguna
E. Donation of 3 seismometers to Northern Cotabato
V. Taal eruption (January 12, 2020)
A. Crowd-sourced tephra fall mapping
B. Base surge mapping
C. Biodiversity mapping
D. Distributed relief goods
E. Distribution of Tents as Triage Areas for Hospitals (Batangas, Laguna, Quezon)
F. Technical Assistance and Post Disaster Assessment in Tanauan, Sto. Tomas, Malvar and Lipa City, Batangas and Cavite PDRRMO
G. 4 publication published for future reference
VI. Typhoon Rolly and Ulysses (October and November, 2020)
A. Technical Assistance and Post Disaster Assessment in Albay
B. Distributed relief goods in San Mateo
C. Simulation of Cagayan River Flooding (Dam release)
VII. Typhoon Odette (December 16, 2021)
A. Deployment of Shelter Tents in Limasawa and Maasin, So. Leyte
B. Deployments of Shelter Tents in CP Garcia, Bohol
VIII. Tropical Storm Agaton (April 2022)
A. Mapping of landslide deposits
B. Mapping of landslide-tsunami impacts
C. Monitoring of tension cracks upslope of Barangay, Bahay with community volunteers.
D. Scientific information updates for the Mayor of Abuyog, MPDO and MDRRMO
Insights and Recommendations
Urgent:
– The GSR has so far not been found. It is recommended for UP to immediately compose a survey team purposely to search for the GSR. This can be headed by and composed of geologists from UP NIGS, in coordination with UP Resilience Institute (UPRI).
– Residents of damaged residential buildings, especially in the far-flung and mountainous villages need urgent technical assistance, as they have not yet been reached by technical teams. It is recommended for UP to immediately deploy more civil and structural engineers to assess the integrity of damaged houses in these far-flung areas (the city and municipal centers have already been assessed by several technical groups such as the Philippine Institute of Civil Engineers (PICE) and the Association of Structural Engineers of the Philippines (ASEP)).
– Condemned buildings, especially in Abra, are at risk of collapsing and pose an imminent danger to those living within the vicinity. The Provincial Capital is in urgent need for demolition equipment to fast-track the process of bringing down condemned structures and avoid further harm to people and properties.
– To assist in attending to the mental and psychological needs of affected families, it is recommended for UP to deploy a team of sociologists, social workers, psychologists, and other professionals trained to guide and assist disaster victims.
– There is already a good number of medical teams (e.g., Red Cross, volunteer doctors, etc.) in place, but UP may also field a team to assist in attending to the medical needs of the affected populace especially in Bucloc.
– In the short term, There is an opportunity for the university to provide assistance with regard to the improvement of services concerning the education of children in affected communities, particularly in Brgy. Lumao and Lingey.
– Clean drinking water is lacking. Water purifying facilities are a big help at this point.
In the immediate term:
– It is recommended for UP to establish a fully-funded Quick Response Team that can be deployed quickly in case of disasters. The first 72 hours are crucial during disasters. Teams should be equipped with all-terrain 4×4 vehicles for access to difficult terrain.
– It is recommended for UP to establish a research laboratory focusing on earthquake studies. This can be housed at UP NIGS. The laboratory should at least consist of the following components:
– Earthquake data acquisition and processing laboratory
– Remote sensing data acquisition and processing laboratory, with access to interferometric satellite data including Sentinel and ALOS 2 data sets
– Automated Unmanned Vehicle (AUV – drone) instrumentation for quick aerial mapping of disaster-stricken areas for timely use