October 3, 2023 Tsunami: South Lhonak Lak, Sikkim, India
A tsunami caused by a landslide began at South Lhonak Lak, Sikkim, India on October 3, 2023 at 16:42:20 UTC. The water rose as high as 15 meters. Its effects were recorded at 1 place. It killed 55 people, counting the earthquake or eruption that caused it.
Where the waves reached
The source (white) and every runup with a place, colored by the water height recorded there. A ring is a runup NCEI marks doubtful.
- Under 1 m
- 1 to 3 m
- 3 to 10 m
- 10 to 30 m
- 30 m and more
- Height not recorded
The tsunami
- Date
- October 3, 2023, 16:42:20 UTC
- Source
- South Lhonak Lak, Sikkim, India
- Cause
- Landslide
- Maximum water height
- 15 m (49.2 ft)
- Runups recorded
- 1
- Waters
- A lake or river, not the ocean
- How certain
- Probable tsunami
- Source location
- 27.950° N, 88.333° E
The toll
- Deaths
- 55 with the earthquake or eruption that caused it
- Missing
- 74 with the earthquake or eruption that caused it
- Damage
- Extreme (about $25 million or more) with the earthquake or eruption that caused it
- Houses destroyed
- 84 with the earthquake or eruption that caused it
Where the literature gives no number, NCEI records a description on a scale of 1 to 4, printed here in its words. Damage is in millions of US dollars of the year of the event, not adjusted for inflation.
What the record says
NCEI’s account, from the sources it cites.
Reference #14215:
On 3 October 2023, the hazard cascade began with the collapse of ~14.7 × 106 m3 of lateral moraine into South Lhonak Lake (SLL) at 22:12:20 Indian standard time (IST) [~16:42:20 universal time coordinated (UTC)], which caused a tsunami. The wave overtopped and eroded the frozen frontal moraine with a maximum wave run-up ~15 m over the frontal moraine. This resulted in a breach 165m wide (top width) and 55m deep that released~50× 106m3 of water, approximately half of the total SLL volume.
The flood cascade caused extensive damage, more than ~25,900 buildings were inundated, damaged or destroyed; 31 major bridges were lost; and ~270 km2 of agricultural land was affected. The Teesta III hydropower dam was destroyed, and several other dams along the Teesta River were damaged
Note: impacts due to glacial lake outburst flood, not tsunami or landslide.
Every runup
Nearest the source first. Heights are above sea level at the time; a tide gauge reads half the wave’s full height.
| Where | Country | Km from source | Water height, m | Inland, m | Measured by | First wave, UTC | Deaths |
|---|---|---|---|---|---|---|---|
| South Lhonak Lake | India | 1 | 15 | Runup height, post-tsunami survey |
More
Every tsunami in 2023The 2000sTsunamis of IndiaThis day in weather historyAlerts in force
Sources
Tsunami events and runups from NOAA’s National Centers for Environmental Information, Global Historical Hazard Database, cited as NCEI/WDS, doi:10.7289/V5PN93H7. Public domain. Read 2026-10-01. NCEI tsunami event 6077.