The Philippine Space Agency (PhilSA) produced a map showing areas covered by ash deposits (bounded in red) from the reported pyroclastic density current along the Mi-isi gully of Mayon Volcano on 02 May 2026. The ash deposits (shaded in red) were classified using change detection on a Sentinel-2 satellite image from 03 May 2026 (shown top) compared with a reference image from before the event (28 April 2026). The bottom map overlays the projected ash deposit extent to show potentially affected barangays. Based on the analysis, at least 8,544 hectares ( ~85.44 sqkm) were covered by ashfall. For comparison, this area is around half the size of Quezon City. 

The amount of information derived from satellite data is oftentimes constrained by cloud cover. For areas obstructed by cloud cover, ash deposition cannot be directly determined. However, the ash deposit extent could be extrapolated by delineating a region around areas classified to have ash deposits. These results are consistent with projections from atmospheric trajectory modeling and reports from the ground. The map is still subject to ground validation. 

PhilSA’s support through the analysis of satellite data provides wide-area coverage that assists the National Disaster Risk Reduction and Management Council (NDRRMC) 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. 

PhilSA will continue monitoring satellite data as the situation requires. Please follow local and national agencies for the latest advisories.  

(Filipino version: Kuha ng satellite sa mga barangay na apektado ng ashfall 

Gumawa ang Philippine Space Agency (PhilSA) ng mapa na nagpapakita ng mga lugar na apektado ng ashfall (nakamarka sa pula) mula sa naiulat na pyroclastic density current sa Mi-isi gully ng Bulkang Mayon noong 02 Mayo 2026. 

Ginamit ang satellite images mula sa Sentinel-2 noong 03 Mayo 2026 at inihambing ito sa reference image bago ang insidente noong 28 Abril 2026 upang matukoy ang lawak ng ash deposits. Batay sa pagsusuri, tinatayang 8,544 ektarya (humigit-kumulang 85,440,000 metro kuwadrado) ang natabunan ng abo—katumbas ng kalahati ng laki ng Quezon City. 

Gayunpaman, may mga limitasyon pa rin ang satellite data, lalo na sa mga bahaging natatakpan ng ulap, kaya ang ilang bahagi ay tinatayang saklaw lamang. Ang resulta ay tugma sa atmospheric models at mga ulat mula sa lugar. 

Ang ganitong pagsusuri ay tumutulong sa NDRRMC sa pag-monitor ng sitwasyon at pagtukoy ng mga prayoridad na lugar para sa pagtugon. Patuloy na babantayan ng PhilSA ang sitwasyon gamit ang satellite data at pinapayuhan ang publiko na sundin ang mga abiso mula sa lokal at pambansang ahensya.)

Access the high-resolution map and shapefile of the projected ash deposit extent here: https://bit.ly/MayonAshfall 

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

*Updated on 06 May 2026: The map originally indicated 04 May as the date of the Sentinel-2 image used for change detection. The Sentinel-2 image used was captured in 03 May 2026, 10:06 PhST. In addition, an earlier version of the article indicated that 8,544 ha converts to ~85,440 sqkm, when this should state ~85.44 sqkm. The map and article has since been updated and corrected.