Longonot

Volcano number:222100
Region:Africa and Red Sea
Country:Kenya
Geodetic measurements?Yes
Deformation observation?Yes
Measurement method(s):InSAR
Duration of observation:2004 - 2010
Inferred cause of deformation:Hydrothermal, Magmatic
Characteristics of deformation:

Two phases of deformation are observed at Longonot volcano between 2004 and 2010 (Robertson, 2015; Biggs et al 2009).

June 2004 – March 2006: Biggs et al. (2009) report 4.5 +/- 0.5 cm/yr uplift (ENVISAT). The signal is elliptical, orientated NW-SE, and centred to the western edge of the volcano summit. This signal is best modelled using a penny shaped crack geometry, at 3.7 km depth, and 5.9 km radius.

January 2007 – July 2010: Subsidence of 0.4 +/- 0.4 cm/yr is observed to the SE of the volcano summit. This signal has a radius of 6 km and is nearly circular. A time series of this signal suggests the deformation is linear. This subsidence is best modelled as a point source at 2.3 km.

 

Reference:Biggs, J., Anthony, E. Y., & Ebinger, C. J. (2009). Multiple inflation and deflation events at Kenyan volcanoes, East African Rift. Geology, 37(11), 979-982.
Reference:Robertson, E. 2015. Magma storage and transport at Kenyan Rift volcanoes: a remote sensing perspective. Chapter 2. Ph.D Thesis, University of Bristol, UK.
Reference:Smithsonian Institution Global Volcanism Program
http://volcano.si.edu/volcano.cfm?vn=222100
Location:36.446, -0.914

Longonot is a broad stratovolcano to the SE of Lake Naivasha, seen here from the SSW. The most recent cone is within a 8 x 12 km caldera. Post-caldera flows are also present.  Masai tradition records a lava flow on the northern flank during the 19th century. Photo by Tom Jorstad, 1990 (Smithsonian Institution).