Forming of the Crater
2.13 Forming of the Crater
The series of photographs in figure 25 below represent the changes through time at the main vent of LUSI Mud Volcano. In a time span of 5 years, LUSI has evolved from a small eruption of steam, hot water and mud to a destructive high rate mud flow, engulfing houses, schools, factories, neighboring villages and caused a large-scale ground deformation, damaged the highways, railroad, pipelines, electrical power lines and others; to presently a much more calm low rate ejection of mud and fluid and occasional intermittent stopping of steam eruption. LUSI evolved through time from a localized kilometre-scale fault zone in 2006 and expanded through pre-existing NE-SW Watukosek fault zone pathways in 2010.
May 2006 LUSI mud volcano on its first day, May 29th, 2006. The mud eruption is approximately 200 m from the Banjarpanji-1 well location. Initial eruption in the form of mud and hot water and clouds of steam with a discharge rate of less than 5,000
m 3 /day.
June 2006 In June, the crater had swelled and the discharge has reached approximately 50,000 m3/day, with water temperatures as high as
97 °C.
August 2006
A semi conical structure is starting to form. The volume of water in LUSI is very large reaching up to 70% of the total volume of mud, shown in the picture as water reflection. The low viscosity of the mud results in mud spreads across, extending to large areas instead of building up vertically.
Earth Sciences
May 2007 In May 2007, retaining walls/dykes were built to prevent the mud from spilling over to the villages and major roads. The height of the dykes encircling the center of eruption reached approximately 15 m. The average mud flow rate at the time was around 100,000 m3/day.
May 2008 Ring levees/dyke were rebuilt and raised to prevent overflow of mud into the closest villages. Discharge rate was still around
100,000 m 3 /day with surface water temperatures remain constant at 97 °C.
February 2009 By February 2009, the ring dyke on the south and north sides are rapidly sinking due to subsidence and are difficult to maintain despite efforts to continuously pile with soil and gravel.
July 2009 The ring dyke around the main vent collapsed and sank in July 2009. The eruption discharge rate at this time is reduced by 60% to approximately 40,000
m 3 /day.
Mud Volcano and Its Evolution
January 2010 The diameter of the main crater at this time is approximately 120 m and flowing continuously 30-50,000 m3/day. At times instead of a single crater, it changes to two or three points aligned in the direction of the Watukosek fault. The flow is mainly liquid and hot steam. A gently sloping cone is starting to form. The mud covered area is
mostly wet, covering 80% of the total area. January 2011
At this time the mud flow rates and the scale of steam clouds are reduced. The eruption rate has decreased to less than 10,000 m3/day. LUSI is now entering a new phase, from an eruptive one to a mature and quiescence phase. The mud around the main vent is solidifying forming a dome.
May 2011 The mud volcano viewed from the west side. Note the reduced scale of the clouds of steam.
May 2011 The mud volcano viewed from the north side with the Watukosek escarpment hills and Mt. Penanggungan in the background.
Fig. 25. Changes from time to time at the main vent of LUSI Mud Volcano
Earth Sciences
Fig. 26. Map interpretation of the results around the center of LUSI from IKONOS imagery using ERMAPPER Software from 2007 to 2011. The interpretation shows a decrease in the volume of hot mud around the main vent. In 2007, almost all the fluid inside the dyke is above 60 o
C. By November 2007, the rate of hot mud has begun to diminish. A year later, in December 2008, the LUSI morphology dome has begun to form. The next phase was the reduced production of hot mud in the main vent and the heightened dome coupled with the formation of the patterns of mud and water flow in the vicinity. (source: BPLS 2011)
Mud Volcano and Its Evolution