Zamboanga del Sur sits on Illana Bay with steep ground rising close behind the coast. Here is what to screen at an exact address.
Zamboanga del Sur curves around the eastern side of the Zamboanga Peninsula, facing Illana Bay and the Moro Gulf. Pagadian is the main city, and like most settlements here it sits where the hills meet the water.
That "hills meet the water" arrangement is the whole hazard story. It compresses three different problems into a narrow band.
Illana Bay and the Moro Gulf open to the Celebes Sea. Coastal towns from Pagadian round to Dumalinao, Tukuran, and the Dinas and Margosatubig side sit on that water.
Screen mapped storm surge exposure against elevation for any coastal address, as one answer rather than two.
There is a second coastal consideration in this part of Mindanao that deserves naming plainly: the Moro Gulf region has a documented history of a destructive tsunami following a large offshore earthquake in 1976. Tsunami is not a mapped layer on a hazard screening and it is not the same phenomenon as storm surge, but the practical response overlaps. Know where the nearest high ground is, know how long it takes to reach on foot, and treat strong ground shaking near the coast as its own instruction to move uphill without waiting for an announcement. PHIVOLCS is the authority here.
Pagadian is well known for streets that climb. Where the terrain rises quickly from the shore, three things follow: short steep catchments, cut slopes for every road and building pad, and landslide susceptibility that varies sharply over short distances.
For any address with slope above or below it, read:
Short catchments deliver rain to the lowland fast. Screen flood susceptibility and the distance to the nearest mapped waterway together, and treat the waterway distance as meaningful even for a channel that is usually dry.
Where a steep valley opens onto the coastal flat, check the debris flow and alluvial fan flags. That flat ground is convenient and it was built by the events you are screening for.
The Zamboanga Peninsula is not seismically quiet. Read the distance from your point to the nearest mapped active fault as an input for a licensed structural engineer, not as a verdict on the lot. The reasoning is in magnitude and intensity are two different numbers.
Mindanao sees fewer direct typhoon landfalls than Luzon, so "when was the last typhoon" is often the wrong question. The right one is when it last rained hard for several days, and what happened here when it did.
People answer that question well. They remember which street went first, which slope moved, and how long the road was cut.
A hazard screening reads public national datasets at a point and reports mapped susceptibility, elevation, slope, and distances. It does not rate tsunami, assess a retaining wall, or measure soil at depth. PHIVOLCS is the authority on earthquakes and tsunami, the MGB on local geohazard assessments, and a licensed geotechnical engineer on anything you build.
CheckHazard does not replace a professional geotechnical or engineering survey.