The Philippine Space Agency (PhilSA), in coordination with the Department of Environment and Natural Resources – Mines and Geosciences Bureau (DENR-MGB), produced a map showing the landslide area at Mt. Balikabok in Subic, Zambales from the landslide that occurred on 30 August following prolonged rains throughout the month brought by the Southwest Monsoon (Habagat). The total area of the landslide is about 110 hectares (~1.1 sqkm), or approximately half the size of Bonifacio Global City, as seen from space. 

This represents a considerable volume of sediment, mud, gravel, and large boulders that collapsed and entered the stream network, was transported for at least 10 km from the source, and contributed to flooding in the barangays of Pita, Dalao, and Pagalanggang, in Dinalupihan, Bataan. This incident shows how prolonged rainfall can progressively saturate a mountainous watershed before intense rainfall triggers slope failure and initiates a downstream hazard cascade. (Project NOAH Open-File Reports)

The landslide area was identified through observing vegetation loss between pre-disaster (06 April 2026) and post-disaster (13 September 2026) images from Sentinel-2 satellite imagery. Areas that appear green and covered in vegetation in the top (pre-disaster) image that now appear brown in the bottom (post-disaster) image indicate bare soil and are possible landslide areas. Vegetation loss was quantified by a significant decrease in Normalized Difference Vegetation Indices (NDVI) between satellite images. The map is subject to ground validation. 

PhilSA’s support through the analysis of satellite data provides wide-area coverage that assists the relevant agencies in monitoring the situation and prioritizing areas for response. By making space data accessible to stakeholders, PhilSA enables informed decision-making and strengthens disaster response. 

Access the high-resolution map here: https://tinyurl.com/Landslide-20260913-S2  

Follow us on social media for the latest updates: https://linktr.ee/philspaceagency 

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Filipino version:

Ang lawak ng gumuhong lupa sa Mt. Balikabok, makikita sa satellite data 

Gumawa ang PhilSA, sa tulong ng DENR-MGB, ng mapa na nagpapakita ng landslide area mula sa landslide na naganap noong 30 Agosto sa Mt. Balikabok sa Subic, Zambales mula sa patuloy na pag-ulan noong buwan ng Agosto dala ng Habagat. Ang kabuuang lawak ng landslide area ay 110 hectares (~1.1 sqkm) na halos kalahati ng Bonifacio Global City. Ang landslide na ito ay naging debris flow at baha na umagos paibaba sa mga barangay ng Pita, Dalao, at Pagalanggang sa Dinalupihan, Bataan. 

Gumamit ang PhilSA ng mga satellite imagery mula sa Sentinel-2 upang obserbahan ang pagbabago ng lugar matapos maganap ang landslide. Makikita ang posibleng landslide area na dating mapuno ay naging kayumanggi gawa ng pagguho ng lupa. 

Isa itong halimbawa kung paano nakakatulong ang satellite data na mapahusay ang ating pagtugon sa sakuna.