Documenting history: Google Earth Images of the Teesta Valley before and after the Oct 2023 GLOF disaster.

Google Earth has recently updated its satellite imagery of the Teesta Valley, and high-resolution images from as recently as 2026 are now available. This allows us, for the first time, to view satellite imagery of the entire Teesta Valley following the devastation caused by the GLOF of 3–4Oct2023 from South Lhonak lake in North Sikkim.

It is unfortunate that satellite images from 2023 or 2024 are not available, as these would have revealed the true extent of the destruction in the immediate aftermath of the GLOF. The 2025/26 imagery, by contrast, shows many locations after significant repairs and reconstruction have already taken place. Also a word of caution here: the updated image and the older image are taken at different times and months of the year as such show shadow areas and colors differently.

Nevertheless, these images provide an important historical record of the largest GLOF in the Himalayas. When juxtaposed with earlier images of the same areas from 2022, they reveal the extraordinary scale and humongous power of nature as the GLOF swept down the Teesta Valley.

STH surveyed the GLOF-stricken areas soon after the disaster, and we already have a substantial report on the event in this blog. In this photo report, I have supported the satellite images with photos of the event from the ground in order to provide a closer look at the devastation.
For those interested, I have also uploaded  a presentation on YouTube, with approximate timelines and details of the disaster. Scientific details on the GLOF are available here.

1. Areas near South Lhonak lake (26°51.419’N 88°26.602’E)

Google Earth images of 2018 (top) and 2026 (below)

Slope profile from A (4472m) to B (3292m) along the river valley -distance 14.7km

2. Lachen town area (27.7167° N, 88.5578° E)

 

Google Earth Images of 2022 (top) and 2025 (below)

Slope profile from A (3278m) to B (2235m) along the river valley -distance 14.4km

3. Areas north of and near to Chungthang (27.613133° N 88.631783°E)
 

Google Earth Images of 2022 (top) and 2025 (below)

                            The Teesta Valley north of Chungthang, December 2023. 

The October 2023 GLOF transformed the valley into a vast corridor of destruction, scouring away entire forests and carrying millions of tonnes of rock, sediment and debris downstream. Buildings, roads and hydroelectric power infrastructure were damaged or swept away, leaving a devastated landscape in its aftermath.

The army lost a lot of hardware, munitions and equipment in the GLOF and the ammunition depot at Munshithang just north of Chungthang was all but wiped out.

4. Chungthang town (27.6045° N  88.6456° E)

                                                    Google Earth Images of 2022 (top) and 2025(below)

Chungthang, the gateway to North Sikkim, sat at the scenic confluence of the Lachen and Lachung Chu (Chu means river in Tibetan). This strategic town was tragically altered around midnight on 04Oct2023, when the GLOF surged down the Lachen Chu. The deluge obliterated much of the town.

Chungthang town on 05Oct2023.

Drone image of Chungthang town, on 17Nov2023 when we visited the place.

5. 1200MW Teesta III dam at Chungthang (27.6045° N  88.6456° E)

Google Earth Images of 2022 (top) and 2025 (below)

Chungthang town owed much of its development to the presence of the 1200MW Teesta III dam (or the Sikkim Urja dam) which was commissioned in Feb 2017 and the town became a tourist hub for travelers going towards Lachen or Lachung in North Sikkim.

The GLOF of Oct2023 destroyed the dam, shortly after midnight on 04Oct2023. The precise time of collapsed may never be known as it was pitch dark, raining with the noise of the GLOF hitting the town. In this melee, residents of the town were busy scrambling to higher ground to save their lives to notice when the dam collapsed. They only came to know about it at dawn on 04Oct2023.

  Image of the collapsed Teesta III (Sikkim Urja) dam taken a few days after the dam was         destroyed.

Drone STH image of destroyed dam with Chungthang town in background -17Nov2023

6. Hanuman Mandir (south of Chungthang - 27.58310°N  88.65591°E)

Google Earth Images of 2022 (top) and 2025 (below)

 7. Naga Village (Mangan district, North Sikkim  27.545367°N 88.628383°E)

Google Earth Images of 2022 (top) and 2025 (below)

The village of Naga (Mangan district, Sikkim), located along the Mangan-Toong road suffered catastrophic landslides after the GLOF swept past it in the valley below. Many residents have since left the village for safer places.

                   Drone image of Naga village landslides taken by STH on 17Nov2023

8. Rangpo town (27.175° N, 88.530° E)

Google Earth Images of 2022 (top) and 2025(below)

The GLOF struck Rangpo—a bustling commercial and transit hub in the Pakyong district—in the early hours of 04Oct2023. Thanks to early warnings received on cell phones from friends and relatives upstream, most residents managed to scramble to higher ground. However, those who did not heed the alerts were tragically swept away.
The Teesta River rapidly submerged the low lying areas of IBM complex and bazaar in the northern part of the town. When the floodwaters finally receded, they left the entire bazaar buried under more than 10 feet of sludge and sand.

        Telephoto image of Rangpo on 06Oct2023 when STH visited the town.

Heavy construction equipment buried under more than 10 feet of sludge and sand at IBM bazar in Rangpo - photo by STH on 06Oct2023

Portions of buildings being excavated in IBM bazar, Rangpo in Dec2023 after the GLOF buried everything under more than 10feet of sludge on 04Oct2023.

Drone image of IBM bazar on 19Mar2025. Much of the sand and debris has been cleared and the Red and Green buildings seen in earlier image are now clear of the sludge.


9. Melli town (27.0906°N 88.4561°E)

  Google Earth images of 2022 (top) and 2025 (below)

Melli is a small town, on the banks of the Teesta river, which straddles both the states of Sikkim and West Bengal (Kalimpong district). The GLOF of 04Oct2023 affected both states.
The top Google Earth image of 2022 shows the sports stadium and parts of Melli town prior to the GLOF.
The lower image shows the impact of the GLOF where the Teesta river now flows on the edge of the stadium. The river flooded the stadium during the GLOF and since the river level has risen by almost 10-15 feet after the GLOF, it routinely floods the stadium after heavy rain (see below)

Drone image Melli stadium of Sep2024 covered with sludge and sand

 

10. Tribeni 
(Confluence of Rangeet and Teesta river - Kalimpong district - 27.079767°N  88.430950°E)

Google Earth images of 2021 (top) and 2025 (below)

Tribeni Covid Hospital is located at the confluence of the Rangeet (dark blue) and Teesta rivers and was used effectively as a isolated treatment centre for Covid patients. The GLOF reached here in the early morning of 04Oct2023 and submerged the road access to the area  from Teesta bazar as well as severely damaged the structure and the compound of the hospital.

Tribeni Covid Hospital on 24Jul2024, approximately one year after the GLOF hit the area.

11. Teesta Bazar (27.059722° N 88.426111° E)

Google Earth images of 2021 (top) and 2025 (below)

The GLOF crashed into Teesta bazar at around 4.00am on 04Oct2023. Residents we interviewed talk about a wall of water coming towards them with cars bobbing up and down in it with headlights on - like little toys in a bathtub. Praveen Chhetri my young colleague from STH reached Teesta bazar the same morning and has photographed some of the most dramatic photos of a GLOF in progress.

The GLOF hitting the Teesta bazar on 04Oct2023 and the same area and buildings seen below in a photograph of 21Jul2024.

Coincidentally all the above photos are approximately of the same area in Teesta bazar as the photo from the 04Oct1968 Darjeeling-Sikkim disaster. See photo below:

 

 

12. Geil Khola (27.029213° N  88.427925°E) 

Google Earth images of 2022 (top) and 2024 (below)

The GLOF reached Geil khola , a transit point on NH10 near the Teesta Bazar, in the early hours of 04Oct2023 and quickly swallowed up the low lying areas of the hamlet. The half buried houses in the red circle are visible in the lower satellite image.
A more recent image of the same area showing the devastation by the GLOF is placed below:

I have documented these Google Earth images of the Oct2023 GLOF disaster along with supporting photos by STH and other known persons in an attempt to preserve a photographic record of a momentous disaster in our region.
While so doing, I found that most of the updated Google Earth images were from 2025, two years after the GLOF took place, nevertheless they do provide an visual indication of the scale of the disaster when compared to earlier images of the same region.
For those who are would like to know why the imagery is clustered around two areas (see map), I would say, these were the areas where the most devastation took place and also where population density is the highest.

My thanks to all those whose photos I have used in the above report

Praful Rao

savethehills@gmail.com

9475033744

Commemorating the 'Teesta Valley GLOF of 04Oct2023' with photos of the event and its aftermath.

A woman washes the money she recovered while scavenging for lost property in a flood affected area of Rangpo (Sikkim) on 06Oct2023 - photo credit Praveen

As I write, it is very early morning on 04Oct2024 and it was exactly at this time last year that I was up at my home in Kalimpong, trying to contact and verify with people, mainly in Sikkim, about whether a GLOF had actually taken place in the Teesta valley.
In the meantime my cellphone was receiving images and videos of the floods as the wall of water tore down the valley. Just verifying what was happening in order to report and record it accurately  kept me engaged the entire day and next, while my young friend and photographer Praveen Chhetri visited Teesta Bazar which the GLOF hit around 4am. He recorded the impact of the GLOF as it happened.
I did not know then that this process of recording the GLOF and its impact would keep us busy for an entire year but it has - and has required numerous visits to many parts of the Teesta valley including one trip made in Nov2023 to Chungthang where the 1200mw Sikkim Urja hydroelectric dam was destroyed by the GLOF.
What we have in this blog is perhaps the most comprehensive photographic record of what was the largest GLOF which took place in the Himalayas. Praveen and I certainly have hundreds of images, many videos and voice recordings of the interviews of affected people that we did during the course of the year.

    Interviewing an affected person who had lost everything to the GLOF - Rangpo (Sikkim), 06Oct2023.

This post, where I publish some photos is only to commemorate that momentous event which changed the lives of so many
Lest we forget...

Army personnel recovering buried vehicles at Bardang (Sikkim) on 06Oct2023. 22 army persons who were a part of a convoy were swept away by the GLOF here

Landslide affected areas of Naga, a village between Mangan(district headquarters, North Sikkim) and Chungthang in Nov2023 (telephoto image from opposite hill). The village was almost entirely evacuated during the monsoons of 2024.

A man crosses the Teesta river on a bamboo bridge at Toong, North Sikkim in Nov2023. The bridge connecting Chunthang to Mangan was torn down by the GLOF

GLOF affected areas between Chungthang and Lachen town where there was no impact of the Sikkim Urja dam burst. The scale of the devastation caused by the GLOF alone is apparent in the photo - photo courtesy Dathup, Lachen.

GLOF eroded parts of NH10 between Teesta bazar and Melli in Oct 2023. With the Teesta river running 4-5m above the pre-GLOF levels, the erosion of NH10 increased remarkably in 2024.

Debris and vegetation which the GLOF had dumped on top of the NHPC Stage V 510MW dam at Dikchu, SIkkim. The Teesta river 'over toppled ' ie went over the dam at this site.

Tree stumps and debris inside the NHPC Stage VI dam at Sirwani, Singtam (Sikkim), Nov2023

Vehicles strewn around like battered toys, on the banks of the Teesta at Singtam (Sikkim).

Part of Teesta town (Krishnagram or Bhasuwa) literally sliding slowly into the river - Sep2024

A marooned COVID hospital on the banks of the Teesta and Rangeet rivers at Tribeni, (Darjeeling district) - Sep2024. There is no road access to the hospital with the Teesta river having kept large parts of the access road submerged after the GLOF.

Rangpo town in Sept24. One year after the GLOF, parts of the town are still trying to recover. The river still flows uncomfortably close to the town and the police checkpost (green roofed structure on the top left is literally tilting into the river.

Undoubtedly one of the most iconic images of a GLOF.

Drone image taken by Praveen at around 11.00am on 04Oct2023 from the Teesta bridge when the GLOF was passing thru the area. As can be seen much of the Teesta bazar was already submerged.

Documentation of parts of the above report was supported by Royal Enfield, as part of their Social Mission Initiative


With
Praveen Chhetri (9733185815)

Praful Rao
SaveTheHills
9475033744
savethehills@gmail.com

Impact of the Oct 2023 Teesta Valley GLOF: Photosurvey of the Geil khola - Likhu bhir section of NH10 on 23Aug2024

NH10 winds itself along the banks of the Teesta river. Gangtok and Kalimpong are towards the right hand side whereas Siliguri is towards the left.

The monsoons have been playing truant in our region recently. Broadly speaking, after the heavy rains in Jun2024, going into mid July, we had less rain towards the latter part of July2024 and deficient rains in August2024.
The deficient rainfall is worrisome in terms of water availability in our region but has allowed the NH10 repairs to progress and yesterday (23Aug2024) the highway was declared open once more:

I photographed the Geil Khola - Likhu Bhir section on 23Aug2024 and have placed several large images of this area which has been one of the most troublesome part of NH10 for maintenance after the Oct 2023 Teesta Valley GLOF in the hope that it may benefit  researchers, engineers and especially lay people who use the highway. You might even like to compare these recent images with our report of the same area done on 18Oct2023.

With the river flowing 4-5m above pre-GLOF levels, it is now running close to the level of the road (and also closer to the IRCON tunnel as well), increasing erosion of the road and the maintenance problems. Teesta bridge is in the top right hand corner.

This image clearly shows how close the river is to Teesta bazar (top right hand corner) of which several areas are sinking and the level of the river between Rabi jhora (see map) and the Teesta bridge thru which the Darjeeling- Kalimpong is routed.

Notice the level of the Teesta as it hugs the NH10 in between Geil Khola (extreme right) and the settlement (29Mile or Baluatar) at the center of the photo.

Section of NH10 between Baluatar (settlement on the right hand side) and Teesta Low Dam Project III (TLDPIII), left top.

The Likhu Bhir section of the NH10 - perhaps the most troublesome part for maintenance as well as traffic jams.

Geil khola - Likhu Bhir - Teesta Bridge (top right) section. The post -GLOF Teesta river is flowing bank to bank even with deficient rainfall in Darjeeling -Sikkim Himalaya over the past two weeks. We still have a month or more of rains left.

Documentation of the above report supported by Royal Enfield, as part of its Social Mission Initiative

Praful Rao
SaveTheHills,
Darjeeling-Sikkim Himalaya
savethehills@gmail.com
9475033744