Mid-Term Report Summary - LUSI LAB (Lusi: a unique natural laboratory for multidisciplinary studies of focussed fluid flow in sedimentary basins)
On 29th of May 2006 several gas and mud eruption sites suddenly appeared along a strike-slip fault (Watukosek fault system) in the NE of Java, Indonesia. The eruptions occurred almost two days after a 6.3 M earthquake striking the island of Java. Within weeks, several villages were submerged by boiling mud. The most prominent eruption site was named Lusi. To date, Lusi is still active. This disaster has forced 50.000 people to evacuate and an area of ~7 km2 is covered by mud. The social impact of the eruption and its spectacular dimensions still attract the attention of international media reporting on the “largest mud eruption site on Earth”.
LUSI LAB focuses on five main aspects in order to complete a comprehensive regional investigation: 1) sampling and monitoring of the active Lusi eruption site; 2) monitoring and sampling of the neighbouring volcanic arc; 3) monitoring on local micro-seismicity related to regional seismicity; 4) monitoring of the fault system originating from the volcanic arc, crossing Lusi and extending to the NE of Java island; 5) numerical modelling of Lusi activity and the strike-slip/magmatic complex system.
We have completed several field expeditions investigating the mechanisms of reactivation of the Watukosek fault system that crosses the Lusi locality and continues to the NE of Java. Results show that after the 27th of May 2009 earthquake the lateral movement of this strike-slip system was activated resulting in several aligned eruptions sites including Lusi. Furthermore, our geochemical studies of the erupted fluids reveal a mantle signature and point to a connection with the neighboring Arjuno-Welirang volcanic complex, indicating that Lusi is a sedimentary hosted geothermal system.
We have designed, developed and constructed the Lusi drone. This is a remote controlled hexacopter developed and assembled in order to complete multidisciplinary studies in extreme and inaccessible environments. The Lusi drone allowed us to successfully complete video/photo surveys as well as fluids/mud sampling from the crater, including spot measurements.
In order to estimate the amount of gas that is being released around the Lusi crater area (~7 km2), we conducted two surveys with more than 350 stations (CO2 and CH4 flux measurements) using a closed-chamber flux-meter system and collected more than 60 gas samples to analyze the composition of the seeps and the crater plume.
We also investigated microbial processes, and communities conducted a sampling campaign at the Lusi site collecting samples of fresh mud from the erupting crater using the remote controlled drone. In addition, we completed a transect towards outer parts of the crater to collect older, weathered samples for comparison. The results of the microbial colonies incubation reveal the presence of colonies that appear to be unknown. The presence of active colonies at very high temperatures might represent a novel discovery for microbiologists.
We have now installed a network of 30 seismic stations distributed around the Arjuno-Welirang volcanic arc, along the Waukosek fault and around Lusi. We plan to leave the network installed for almost 2 years (i.e. 1 additional year). The purpose of this long-term monitoring is to observe how local seismicity and/or the frequent seismic activity ongoing in the subduction zone in southern Java affects the activity of the magma chamber, the Watukosek fault system and the Lusi activity. In addition, we have also deployed temporary stations inside the embankment area to observe the activity of the pulsating behavior of Lusi and its geysering bursts. This study is coupled with video observations.
A comprehensive combined electrical resistivity and self-potential (SP) survey was performed in the 7 km2 area inside the Lusi embankment. The goal of the geophysical survey was to map the near-surface occurrence of the Watukosek fault system, upon which Lusi resides, and provide useful data that will be used for more detailed numerical modelling.
LUSI LAB focuses on five main aspects in order to complete a comprehensive regional investigation: 1) sampling and monitoring of the active Lusi eruption site; 2) monitoring and sampling of the neighbouring volcanic arc; 3) monitoring on local micro-seismicity related to regional seismicity; 4) monitoring of the fault system originating from the volcanic arc, crossing Lusi and extending to the NE of Java island; 5) numerical modelling of Lusi activity and the strike-slip/magmatic complex system.
We have completed several field expeditions investigating the mechanisms of reactivation of the Watukosek fault system that crosses the Lusi locality and continues to the NE of Java. Results show that after the 27th of May 2009 earthquake the lateral movement of this strike-slip system was activated resulting in several aligned eruptions sites including Lusi. Furthermore, our geochemical studies of the erupted fluids reveal a mantle signature and point to a connection with the neighboring Arjuno-Welirang volcanic complex, indicating that Lusi is a sedimentary hosted geothermal system.
We have designed, developed and constructed the Lusi drone. This is a remote controlled hexacopter developed and assembled in order to complete multidisciplinary studies in extreme and inaccessible environments. The Lusi drone allowed us to successfully complete video/photo surveys as well as fluids/mud sampling from the crater, including spot measurements.
In order to estimate the amount of gas that is being released around the Lusi crater area (~7 km2), we conducted two surveys with more than 350 stations (CO2 and CH4 flux measurements) using a closed-chamber flux-meter system and collected more than 60 gas samples to analyze the composition of the seeps and the crater plume.
We also investigated microbial processes, and communities conducted a sampling campaign at the Lusi site collecting samples of fresh mud from the erupting crater using the remote controlled drone. In addition, we completed a transect towards outer parts of the crater to collect older, weathered samples for comparison. The results of the microbial colonies incubation reveal the presence of colonies that appear to be unknown. The presence of active colonies at very high temperatures might represent a novel discovery for microbiologists.
We have now installed a network of 30 seismic stations distributed around the Arjuno-Welirang volcanic arc, along the Waukosek fault and around Lusi. We plan to leave the network installed for almost 2 years (i.e. 1 additional year). The purpose of this long-term monitoring is to observe how local seismicity and/or the frequent seismic activity ongoing in the subduction zone in southern Java affects the activity of the magma chamber, the Watukosek fault system and the Lusi activity. In addition, we have also deployed temporary stations inside the embankment area to observe the activity of the pulsating behavior of Lusi and its geysering bursts. This study is coupled with video observations.
A comprehensive combined electrical resistivity and self-potential (SP) survey was performed in the 7 km2 area inside the Lusi embankment. The goal of the geophysical survey was to map the near-surface occurrence of the Watukosek fault system, upon which Lusi resides, and provide useful data that will be used for more detailed numerical modelling.