Weathered granite soil and continuous heavy rain are the geological factors in the landslide that hit the Na Nai area of Patong early on 26 October 2026, according to the Ministry of Natural Resources and Environment (MNRE). In a release published on 28 October, the ministry describes a debris flow of rock, soil and mud on Soi Na Nai 5, Patong subdistrict, Kathu district. It also lists four measures to prevent a repeat. Two of them, a new weir and ground-movement monitoring, are plans with no date or cost.
What the ministry found
MNRE says the slide left granite rocks 10–60 cm across and gravel-sand sediment. The release says water was still running down the soi. Rocks and sediment collected at a weir, or check dam, which was damaged and collapsed. The current then eroded the road and carried rocks and sediment into residents’ houses.
MNRE gives the geological factors as highly weathered Cretaceous-age granite, which forms a sandy-clay soil layer that holds water well and moves easily, together with continuous heavy rain. The ministry puts accumulated rainfall at the site at 340.5 mm, from the Kata community station of Phuket’s provincial water information centre. The release does not say over what period.
According to the release, Natural Resources and Environment Minister Suchart Chomklin ordered the Department of Mineral Resources on 27 October to find measures to prevent a repeat slide in Patong. Department staff then inspected the site with Phuket’s deputy governor, the mayor of Patong municipality and the director of the ministry’s Phuket office. The release does not date the inspection.
The four measures
First, MNRE says Phuket province has declared the affected area an emergency disaster area for flood and mudslide, to speed up assistance. Second, the Department of Mineral Resources and related agencies continue to warn of heavy rain and landslide danger in Phuket and the South. Third, the watercourse is to be diverted by engineering means, with a new weir to raise the water level and send water into drainage pipes; the municipality is to work with the provincial public works office on the analysis and design. Fourth, the municipality plans to work with the department on ground-movement monitoring stations in the risk areas of Patong municipality. The release gives no date, cost or design for the weir or the stations.
What the press reported on the day
Khaosod English reported on 26 October that the area around Makro Na Nai was among the hardest hit. Homes were damaged, belongings swept away, vehicles badly damaged and several shops affected, with no deaths or injuries reported that morning. It reported Phuket’s deputy governor as saying debris lay along about one kilometre and expected clean-up to finish on 26 or 27 October if no more heavy rain fell. Khaosod reported that Patong Municipality designated the area a disaster zone; MNRE attributes the declaration to the province.
The Nation reported the same day that water rushed down Khao 50 Pi hill. It gave a 24-hour reading of 117 mm at Ban Na Yai, a different station and measure from the ministry’s 340.5 mm. It also reported the Thai Meteorological Department’s warning of heavy rain in the South from 25 to 28 October, which could trigger flash floods and landslides, particularly on foothill slopes near waterways.
What was reported after 26 October
The Phuket News reported on 27 October that damage from the 26 October flash flooding and landslides was “provisionally estimated at B100 million”. The Phuket News attributed the estimate to a report by Phuket MP Chalermpong Saengdee. The paper reported that, in a Facebook statement, the MP said the damage in Soi Nanai 5-8 “affected homes, shops, bars, massage parlours and tattoo studios, as well as cars and motorbikes belonging to residents and tourists.” It reported no deaths or injuries. In a background paragraph on the 26 October runoff from the hills, Thai PBS World’s 29 October article said more than 100 households and businesses in Patong were reported affected, with preliminary estimates putting the damage at 100 million baht.
The Bangkok Post reported on 28 October that the mayor of Patong municipality “has blamed encroachment on nearby hills by property developers for causing the huge mudslides”. It reported that “Lalita Maneesri said on Wednesday that municipal authorities had spotted illegal encroachment and land alterations being made at Khao 50 Years hill and were taking legal action against wrongdoers.” Officials told the paper that encroachment and illegal alterations had reduced the forest on the hill that had helped prevent mudslides. This is the mayor’s allegation, and the legal action she describes is the municipality’s own step, not a ruling. The ministry release, as quoted above, lists geological factors.
Thai PBS World reported on 29 October another landslide, which sent soil and rocks onto Na Nai 3 Road. Thai PBS World reported that Patong Municipality advised the public to avoid the road, which was closed after the landslide and falling rocks blocked traffic. It reported that the mayor ordered residents in high-risk areas to evacuate to temporary shelters, with shuttle vehicles for residents of Na Nai 3 and Na Nai 8 roads.
What it may mean for a hillside buyer or owner
The record shows homes, shops and a road damaged below a slope, and a soil type the ministry names as a factor. It does not set any rule for property, and no source reports an effect on prices, rents or listings. For a plot on or below a Patong-area hillside, the sensible step is to look at the slope, the paths water would take, and any weir, channel or drain above the land. The Patong area guide already lists occasional flooding among the area’s traits. The property inspection guide suggests a second visit after heavy rain, as a supplement rather than a must, and lists retaining walls, slopes and settlement around drains among the checks. The due diligence checklist covers the wider purchase.
What is not known
None of the cited sources gives a count of damaged buildings (the 100 households are not a building count), and none states the basis for the B100 million figure. The reports differ on the value of the damage: the Bangkok Post reported on 28 October that local authorities had put the affected households at at least 100 and had yet to estimate the total damage, while The Phuket News (27 October) and Thai PBS World (29 October) carried a preliminary estimate of 100 million baht. No source names the buildings or says whether they were titled land, condominiums or villas, or whether any had building permits. MNRE announces no change to building, zoning or slope rules, and no limit on construction or sale. The weir and the monitoring stations have no date, budget or exact locations.
