Davao de Oro, the province formerly called Compostela Valley, sits inland between the Davao Gulf and the eastern ranges. Nabunturan, Monkayo, Montevista, New Bataan, Maragusan, Mawab, Compostela, Maco and Pantukan are strung through valleys and along the flanks of steep ground.

It has a mining history, particularly around Diwalwal in Monkayo and along the Pantukan coast, and it was one of the two provinces hit hardest by Typhoon Pablo in December 2012.

The valley-mouth question comes first

In New Bataan and elsewhere in 2012, the destruction concentrated on the flat, open ground where steep valleys reach flatter land. Water, soil, rock, and timber came down the valleys as debris flow and spread out where the ground flattens.

That flat ground is where people build, because in mountain country flat ground is scarce. It is flat because material has been delivered there before.

So for any property below or near a slope:

1. The debris flow and alluvial fan flags at the exact coordinates, first. See the debris flow and alluvial fan brief.
2. Distance to the nearest mapped waterway, including the steep creek above the property. A dry gully on a mountain flank is a route, not a feature.
3. Slope at the coordinates and above them. See the elevation and slope brief.
4. Mapped landslide susceptibility.

The full account is in Pablo, December 2012.

Mining ground

Mining and small-scale mining disturb slopes, produce spoil, and change how ground drains. Tailings and waste rock are loose material sitting where it was put, and Pantukan has a documented history of deadly landslides in mining areas.

None of this is a mapped layer. It is a question you ask:

• Is there mining, past or present, on or above this property?
• Is there small-scale mining in the catchment?
• Are there tailings, spoil heaps, or old workings upslope?
• Has any part of this slope failed before?

Ask the MGB regional office and the municipal engineering office as well as the neighbours.

Rivers and the lowland

The Agusan and Hijo river systems drain parts of the province. On the lowland, read flood susceptibility, elevation, and waterway distance together, and ask about duration as well as depth.

The coastal strip

Maco, Pantukan and Mabini reach the Davao Gulf. Screen mapped storm surge exposure against elevation for those addresses.

Faults

Read the distance to the nearest mapped active fault as a design input for a licensed structural engineer, and note that strong shaking on steep, disturbed, or saturated ground triggers slope failure directly. See ground rupture and ground shaking.

Checklist before you commit

1. Screen the exact coordinates, not the municipality.
2. Read the debris flow and alluvial fan flags first for any valley-mouth or below-slope lot.
3. Trace every channel between the high ground and the property, on a map and on foot.
4. Walk uphill and look at the catchment above the property.
5. Ask specifically about mining and small-scale mining upslope.
6. Ask what happened here in December 2012 and what was rebuilt.
7. Commission a soil investigation before designing, and have any structure assessed by a licensed structural engineer.

The rebuild question, again

Reconstruction after 2012 was extensive and varied in quality. Ask what was destroyed, what was rebuilt, who did it, and whether there are plans or permits. Then pay a licensed structural engineer to look. In a province rebuilt at scale, that is the highest-value item in the transaction.

The honest limit

A hazard screening reads public national datasets at a point and reports mapped susceptibility, elevation, slope, and distances. It does not see mining spoil, upstream clearing, or soil at depth, and it cannot assess a rebuilt structure. The MGB regional office, the LGU, and licensed engineers cover what it cannot.

CheckHazard does not replace a professional geotechnical or engineering survey.