Composition and flux of explosive gas release at LUSI mud volcano (East Java, Indonesia)

Abstract

The LUSI mud volcano has been erupting since May 2006 in the densely populated Sidoarjo regency (East Java, Indonesia), forcing the evacuation of 40,000 people and destroying industry, farmland, and over 10,000 homes. Mud extrusion rates of 180,000 m 3 d 21 were measured in the first few months of the eruption, decreasing to a loosely documented <20,000 m 3 d 21 in 2012. The last few years of activity have been characterized by periodic short-lived eruptive bursts. In May and October 2011, we documented this activity using high-resolution time-lapse photography, open-path FTIR, and thermal infrared imagery. Gases (98% water vapor, 1.5% carbon dioxide, 0.5% methane) were periodically released by the bursting of bubbles approximately 3 m in diameter which triggered mud fountains to $10 m and gas plumes to hundreds of meters above the vent. During periods of quiescence (1-3 min), no appreciable gas seepage occurred. We estimate that LUSI releases approximately 2300 t yr 21 of methane, 30,000 t yr 21 of CO 2 , and 800,000 t yr 21 of water vapor. Gas bubble nucleation depths are >4000 m for methane and approximately 600 m for carbon dioxide; however, the mass fractions of these gases are insufficient to explain the observed dynamics. Rather, the primary driver of the cyclic bubble-bursting activity is decompressional boiling of water, which initiates a few tens of meters below the surface, setting up slug flow in the upper conduit. Our measured gas flux and conceptual model lead to a corresponding upper-bound estimate for the mud-water mass flux of 10 5 m 3 d 21.

CO2 flux from Javanese mud volcanism

“…The retrieved CO 2 flux of 117 t d −1 is in line with that measured at the LUSI mud volcano, also located in the Kendeng Basin, 180 km east of Bledug Kuwu (Figure ), which was reported to be between 35 and 160 t d −1 [ Vanderkluysen et al ., ]. This order of magnitude of CO 2 flux compares with the lower end of volcanic emission rates, such as Vulcano, Italy [ Gerlach et al ., ], and, by itself, is dwarfed by the anthropogenic carbon emissions in Indonesia, which are of the order of 274 kt d −1 (http://cdiac.ornl.gov/trends/emis/ido.html).…”

The Plumbing System Feeding the Lusi Eruption Revealed by Ambient Noise Tomography

“…These regions correspond to two fluid sources that were distinguished by geochemical analysis (Mazzini et al, , , ). Furthermore, a magmatic source feeding the Lusi system with intense crustal fluid flow, upwelling from depth, has been put forward based on observations of the eruptive activity coupled with seismic data (Karyono et al, ; Vanderkluysen et al, ). The hot (~100°C) erupted fluids have a geochemical composition that clearly shows a component of mantellic origin mixed with fluids originating from metamorphic reactions at temperatures that are higher than the local gradient (Mazzini et al, , ).…”

“…The eruption site reached flow rates of up to 180.000 m 3 /d (Mazzini et al, ) and currently (February 2017) in the order of 80.000 m 3 /d. Lusi is a unique system on Earth due to its longevity and has been studied extensively over the past decade with geological investigations (Davies et al, ; Istadi et al, ; Mazzini et al, ; Sawolo et al, ; Tanikawa et al, ; Tingay et al, ), geochemical and experimental approaches (Mazzini et al, , ; Vanderkluysen et al, ), geophysical methods (Karyono et al, ; Manga et al, ; Mauri, Husein, Mazzini, Irawan, et al, ; Mauri, Husein, Mazzini, Karyono, et al, ; Obermann et al, ; Shirzaei et al, ), and numerical studies (Collignon et al, ; Lupi et al, ; Lupi et al, ; Mazzini et al, ; Rudolph et al, ; Sohrabi et al, ; Svensen et al, ). However, despite the numerous studies, several questions remain unanswered.…”

Ascent velocity and dynamics of the Fiumicino mud eruption, Rome, Italy

“…Our study of the small Fiumicino eruption complements the recent study of the much larger Lusi mud eruption in Indonesia [e.g., Mazzini et al, 2007Mazzini et al, , 2009Davies et al, 2008;Tingay et al, 2008;Manga et al, 2009] which may have been natural [e.g., Mazzini et al, 2007;Lupi et al, 2013] but possibly also the result of drilling [e.g., Manga, 2007;Davies et al, 2008;Tingay et al, 2008Tingay et al, , 2015 as was Fiumicino. The large size of Lusi, discharge exceeding 100,000 t/d [Mazzini et al, 2007], makes the characterization of transport processes and eruption dynamics [Vanderkluysen et al, 2014] difficult compared to Fiumicino where direct observation and sampling are possible.…”