Walking the Tamugan Fault: How to Check Whether a Davao Home Sits Near an Active Fault

In September we wrote about the magnitude 7.8 earthquake of 8 June 2026, which struck offshore Sarangani, about 180 kilometres from Davao City, and reached the city at Intensity V. One line in that piece pointed to the question it left open: a different fault, closer in, would produce a different number.

Last week the city answered part of that question in the most practical way possible. From 20 to 23 October, its disaster office walked one of those closer faults with the national seismology agency and the Office of Civil Defense, marking homes and structures that sit on or along it and telling the families who live there what that means.

The fault is called Tamugan, it runs inside the city's own boundaries, and according to the city it can generate a magnitude 6.7 earthquake.

What happened during Walk the Fault

According to the city's release of 21 October, the City Disaster Risk Reduction and Management Office (CDRRMO), the Department of Science and Technology's Philippine Institute of Volcanology and Seismology (DOST-PHIVOLCS), the Office of Civil Defense and other agencies held the fifth Walk the Fault from 20 to 23 October 2026.

The four days covered eight barangays: Gumalang, Malagos, Subasta, Tagakpan, Camansi, Cawayan, Alambre and Tagluno. Teams marked areas and structures located on or along the fault. Residents were gathered and told which areas and structures could be affected, what the earthquake hazards are, and what to do before, during and after ground shaking.

The head of the CDRRMO, Alfredo Baloran, made a point that matters for anyone who rents or buys in Davao: many structures directly on or along the fault lines predate the fault-mapping initiatives. In other words, a building standing on a fault trace today was usually built before anyone marked the trace. That is not negligence by the current owner. It is the reason the mapping exists.

The mayor, Sebastian Duterte, in a message read out by Baloran, described the purpose as "validating and documenting fault segments, identifying potentially affected areas and structures, and raising public awareness of earthquake hazard".

The Central Davao Fault System

Tamugan is not alone. The city release describes it as one segment of the Central Davao Fault System, which includes:

• •the Tamugan Fault, about 25 kilometres long;
• •the Lacson Fault, 33 kilometres;
• •the Pangyan-Biao Escuela Fault, 33 kilometres;
• •the Dacudao Fault, 18 kilometres;
• •the New Carmen Fault, 12 kilometres;
• •and the Colosas Fault.

These are the faults that run through Davao City itself, as opposed to the offshore trench that produced the June earthquake.

The city has been walking them year by year. In September 2024, an earlier walk marked fault lines in eight other barangays: Tamugan, Calinan, Riverside, Los Amigos, Tugbok Proper, Bangkas Heights, Binugao and Sirawan. At that event, the PHIVOLCS director, Teresito Bacolcol, reminded residents that the Philippines has 175 active fault segments and that the country sits on the Pacific Ring of Fire. Baloran said residents along faults identified the year before had begun preparing, and that some had become hesitant to build large structures on them.

In October 2025, the fourth edition visited households and establishments on or along active faults, starting in Barangay Mintal, which the city said is traversed by two active faults, the Lacson and the Dacudao. Baloran's message then was that residents along the marked lines are not the only ones at risk: "Tibuok Davao affected", the whole of Davao is affected when an earthquake occurs.

What an active fault actually means

PHIVOLCS defines the terms on its earthquake hazards page, and the definitions are worth knowing before you read a hazard report.

• •An active fault is one that has moved within the last 10,000 years and will move again in the future.
• •A potentially active fault shows deformation, but its activity within the last 10,000 years is unclear. PHIVOLCS says its future movement should not be discounted.
• •Ground rupture is the hazard specific to active faults: the displacement of the ground surface along the fault, producing visible fracturing or cracking.

Ground rupture is the reason the walk matters for individual homes. A building that straddles a fault trace can be torn by the ground moving beneath it, however well it was built. That hazard is narrow and local. It concerns the strip along the trace.

The other hazards from an earthquake are wider. Ground shaking is generally stronger near the epicentre and weaker further away, and it is what damages and collapses buildings. PHIVOLCS also lists liquefaction, which occurs in recently deposited, loose, water-saturated sandy sediments on lowlands near water, such as beaches, riverbanks, reclaimed land and floodplains, and earthquake-induced landslides, which are more likely on steeper slopes.

So there are two different questions for any address in Davao. Is it on or close to a fault trace? And how will the ground and the building respond to strong shaking from a fault nearby or far away? The walk answers the first one for the barangays it covers. The second one depends on the soil and the structure.

How to check an address yourself

You do not need to wait for the walk to reach your barangay. PHIVOLCS makes its hazard information public, and two routes are free or nearly free.

HazardHunterPH. The HazardHunterPH web application, run by DOST-PHIVOLCS under the GeoRiskPH initiative, lets you pick a location on a map and generate a hazard assessment report with explanations and recommendations. According to its FAQ, it shows whether a location is prone to seismic, volcanic or hydro-meteorological hazards, gives the distance from active faults and volcanoes, and draws on information from PHIVOLCS, PAGASA and the Mines and Geosciences Bureau. The reports are free. It runs in a phone browser, so you can check an address while you are standing in front of it.

PHIVOLCS hazard maps. The institute's earthquake hazard maps can be downloaded as files for Google Earth, by region, province and municipality. PHIVOLCS notes that availability varies by area and that maps may be revised as new information comes in.

A signed Hazard Assessment Report. If you need something on paper, for example before a purchase or a long lease, PHIVOLCS issues a Hazard Assessment Report for a specific parcel of land through its online Hazard Assessment Service. The PHIVOLCS Citizen's Charter 2026 lists what you submit: a vicinity map showing the parcel boundary on a Google Earth map or image, and a copy of the Transfer Certificate of Title or Tax Declaration if available. If neither is available, you give the address instead. The fee is ₱100 per site for individual private property owners and ₱500 per site for private companies, and a simple request with one or two sites takes three working days.

The charter is explicit that the report is not an approval, endorsement or authorisation for any further government procedure. It tells you what hazards are present. It does not certify a building.

What the walk does not tell you

The releases name barangays, not street addresses, and they do not publish a list of the marked structures. That is sensible for the families concerned, but it means a reader cannot look up a specific house in them. It also means the absence of a barangay from the lists says nothing either way: the city has walked parts of the fault system over several years, not the whole of it at once. For any individual property, HazardHunterPH and the PHIVOLCS maps are the place to start, and the signed report is the place to finish.

What it means if you rent or buy

Check before you sign, not after. A free HazardHunterPH report takes a few minutes. If an address shows up close to an active fault, that is information you want before a deposit changes hands. Our rental guide covers the rest of what to check before you sign a lease.

Distance from a fault and building quality are separate questions. The September piece on the June 2026 earthquake showed that damage in the city followed construction and condition, not postcode: offices, homes and public housing across different areas were tagged. A home far from any fault trace can still be badly built. A home near one is exposed to a hazard no construction fully removes.

Know which barangays have been walked. The barangays named in the 2024, 2025 and 2026 releases are where the city and PHIVOLCS have confirmed faults on the ground. If you are looking in one of them, ask the barangay hall or the landlord whether the property was among the structures visited or marked. A household that took part will know.

Think about the ground, too. Our neighbourhood guide describes where foreign residents tend to live. For any area, it is worth asking whether the property sits on low, soft ground near the river or the coast, or on a steep slope, because PHIVOLCS names those as the settings for liquefaction and earthquake-induced landslides.

Practise the basics. The city's message at every Walk the Fault has been preparation: what to do before, during and after shaking. Learn the drill once with everyone in your household. A small go-bag with water, a torch, a power bank, medication and copies of your passport and visa documents costs very little to keep.

What the walk says about the city

There are two ways to read news like this. One is that Davao has faults running through it. That is true, and it was true long before anyone walked them. The other is that the city knows where they are, is telling the people who live on them, and has done so every year, in public, with the national agency at its side.

That second reading fits what we described in our piece on why Davao feels safer than many people expect: an administration that treats practical risk as its job. It also completes the picture from our piece on typhoons and rain: a city that sits below the typhoon belt still has its own ground to understand.

The useful takeaway is simple. Every address in Davao can be checked for its distance from an active fault in a few minutes, for free, using the government's own tools. Doing that before you rent or buy turns an abstract risk into a known one, and a known risk is one you can plan around.