Police station and residential buildings evacuated after giant sinkhole opens in Bangkok, Thailand.

Several residential buildings as well as the Samsen Metropolitan Police Station remain closed after a sinkhole approximately 30 m wide and more than 15 m deep opened up beneath the Samsen Road in the Dusit District of Bangkok, Thailand, on Wednesday 24 September 2024. The nearby  Vachira Hospital has been able to remain open, benefiting from a system of deep piles intended to keep it stable during Earthquakes. The sinkhole swallowed a number of vehicles, as well as several electricity pylons, but nobody was injured during the incident.

A massive sinkhole which opened up in Bangkok, Thailand, on 24 September 2025. Chalinee Thirasupa/Reuters.

Sinkholes are generally caused by water eroding soft limestone or unconsolidated deposits from beneath, causing a hole that works its way upwards and eventually opening spectacularly at the surface. Where there are unconsolidated deposits at the surface they can infill from the sides, apparently swallowing objects at the surface, including people, without trace. 

Bangkok is known to be prone to such problems, being situated on a flat plain of alluvial sediments, and having historically suffered from widespread subsidence due to over-extraction of water from underlying aquifers. This incident was initially linked to heavy rainfall in the area, linked to the local rainy season, which peaks in September. However, subsequent investigations have suggested that vibrations from tunnel excavations for a new subway system may have led to the breakage of a water main, causing water to gush into, and erode, the soft sediments beneath the Samsen Road.

Water gushing from a broken water main into a newly opened sinkhole on 24 September 2025. Thailand Construction News.

Soil liquefied by the initial water main break flowed into the under-creation Purple Line Tunnel, creating a void which undermined further water mains, causing them to sag and break, releasing more water and causing the rate of erosion to increase, leading to the dramatic emergence of the sinkhole at about 7.00 am on 24 September. 

This situation was made worse by initial attempts to fix the problem, which involved pouring 700 cubic meters (about 1500 tonnes) of liquid concrete into the hole. This concrete also found the gap into the tunnel system, with its additional mass causing a 30 m² breach into the tunnel system to open up, through which the concrete flowed into the tunnel.

Engineers must now wait for the concrete to set before clearing out and stabilising the breach, then filling in whole, whilst at the same time preventing water from the seasonal rains entering the hole. Initial concerns that the newly constructed Samsen Metropolitan Police Station would need to be demolished have now been dispelled, but engineers are warning that it may be over a year before it is possible for it to reopen. 

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Ceres comes to opposition.

Dwarf Planet 1 Ceres will reach opposition (the point at which it is directly opposite the Sun when observed from the Earth) at 1.12 pm GMT on Thursday 2 October 2025, when it will also be at the closest point on its orbit to the Earth, at a distance of 1.96 AU (i.e. 1.96 times as far from the Earth as the Sun, or about 239 361 000 km), and be completely illuminated by the Sun. While it is not obvious to the naked eye observer, asteroids have phases just like those of the Moon; being further from the Sun than the Earth, 1 Ceres is 'full' when directly opposite the Sun. As 1 Ceres is only about 939.4 km in diameter, it will not be visible to the naked eye, but with a maximum Apparent Magnitude (luminosity) of 7.6 at opposition, it should be visible in the Constellation of Cetus to viewers equipped with a good pair of binoculars or small telescope, with the best visibility being at about midnight local time from anywhere on Earth.

The calculated orbit and position of 1 Ceres at 1.00 pm GMT on Thursday 2 October 2025.  JPL Small Body Database. 

Because Ceres is further from the Sun than the Earth, its orbital period is much longer than ours, with the Dwarf Planet completing one obit every 1683 days (4.65 years), on an eccentric orbit tilted at 10.6° to the plane of the Solar System. The orbit of Ceres places it within the inner part of the Main Asteroid Belt, but due to its large size, with a diameter of 939.4 km, it is considered to be a Dwarf Planet rather than an asteroid.

High resolution image of Ceres made on 20 September 2020, by the Dawn Space Probe. Wikimedia Commons/NASA/JPL/Caltech.

Ceres was discovered on 1 January 1801 by Giuseppe Piazzi, a Catholic priest at the Academy of Palermo, Sicily. It was the first body to be discovered in the Main Asteroid Belt, and at the time when it was discovered an international search was underway for a presumed 'missing planet' between the orbits of Mars and Jupiter (although Piazzi was studying stars when he first observed Ceres, and initially presumed he had found a new comet). Ceres was for a long time considered to be the largest asteroid in the Solar System, but in 2006 was re-classified as a Dwarf Planet, as part of a revision of the classification of Solar System bodies driven by the discovery of a growing number of bodies in the Outer Solar System which are too large to be considered asteroids or comets yet to small to be considered to be planets. 

Of the ten bodies currently classified as Dwarf Planets, only Ceres is located within the Main Asteroid Belt, with five lying in the Kuiper Belt (Orcus, Pluto, Salacea, Haumea, Quaoar, and Makemake), two lie within the Scattered Disk (Gonggong and Eris), and one within the Detached Region on the outer fringe of the Solar System (Sedna).

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