Available Weekly Reports
| Longonot |

There are no activity reports for Longonot.
Summary of eruption dates and Volcanic Explosivity Indices (VEI).
| Start Date | Stop Date | Eruption Certainty | VEI | Evidence | Activity Area or Unit |
|---|---|---|---|---|---|
| 1863 ± 5 years | Unknown | Confirmed | 0 | Anthropology | Northern flank |
| 1330 BCE ± 100 years | Unknown | Confirmed | Radiocarbon (uncorrected) | ||
| 7200 BCE ± 100 years | Unknown | Confirmed | Radiocarbon (uncorrected) |
The trachytic Longonot stratovolcano SE of Lake Naivasha in the Gregory Rift valley contains a 8 x 12 km caldera. Formation of the caldera accompanied large explosive eruptions about 21,000 years ago. A large central cone that was constructed within the caldera forms the 2776-m-high summit of the volcano. The younger cone is truncated by a circular, 1.8-km-wide crater. Post-caldera lavas are found on the caldera floor and the volcano's flanks, marking a late stage of effusive eruptions. A well-preserved satellitic cone is located on the NE flank. Masai tradition records a lava flow on the northern flank during the 19th century. Similarly youthful-looking lava flows occur on the SW flank.