Activity: 1993-1998

After May 1993 the activity returned to the type typical of the years since January 1983, with small spatter cones (the photograph to the left below, taken by Celia Nyamweru on 16 July 1996) and low viscosity pahoehoe flows (the photograph to the right, taken by Bernard Saunders in February 1996). Contrast the flow across the centre of Saunders’ photo, which is long and very thin (probably less than 50 cm thick) with the corner of Chaos Crags just visible on the left side of the photo. In the years after this photo was taken in February 1996 the whole of Chaos Crags became covered by younger pahoehoe flows.

One small blocky flow similar in appearance to Chaos Crags was extruded in 1996 (look at the figure on the natrocarbonatite page) but it became covered by younger lavas before it could be sampled and analysed. The crater floor has continued to rise as more lava flows form, and so the crater walls are becoming progressively lower. Later on this site you will learn when the first breach in the crater wall occured, allowing lava from vents within the crater to spill down the outer walls of the cone. In the long run the crater might return to the situation described in 1910 by C. Uhlig, quoted in Dawson et al. (1995: 7) “The northern crater had only a horse-shoe-shaped southern rim immediately below the summit, and lacked a crater rim to the north, west and east. The crater was more like a platform on which there was a central cone from which gas was being emitted”.

The next three photographs were all taken looking north from about the same position, high on the southern slopes above the crater, and show how the crater has become steadily shallower over the last 10 years.

Photograph taken in 1988 Photograph taken in February 1997
Photograph taken in July 1997
Photograph taken in 1988 Photograph taken in February 1997 Photograph taken in July 1997

The following photograph shows the lowest point on the northwest rim; from the height of the standing person we can estimate the height of the northwest wall on 23 February 1998 as about 4-5 metres. This photo was taken by Josh Lane.

Observations and photographs of Fred Belton and Chris Weber showed that on 2 to 7 August 1998 the northwest wall was about 20 cm (that is 8 inches!) above the crater floor. Several new cones had formed in the central part of the crater floor, as shown in the following photographs by Fred (on the left) and Chris (on the right). The white patch on the northwest wall in the right hand photograph suggests that lava may have erupted in this area a few weeks or months before the photograph was taken in early August. Other photographs taken in early August 1998 showed that the crater wall was also very low on the east side.

Activity continued through the later months of 1998; the photograph to the left, taken by Burra Gadiye on 29 September 1998, shows very recent lava flows extending both to the west and to the east from vents on the slopes of the T37 cluster of cones. The northwest wall is (just) visible in this photograph. On 1 November 1998 Burra Gadiye photographed very fluid pahoehoe escaping from a vent close to T37 (photograph to right, below).

What happened after 1998?

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