Bubble mobility in mud and magmatic volcanoes

Abstract

The rheology of particle-laden fluids with a yield stress, such as mud or crystal-rich magmas, controls the mobility of bubbles, both the size needed to overcome the yield stress and their rise speed. We experimentally measured the velocities of bubbles and rigid spheres in mud sampled from the Davis-Schrimpf mud volcanoes adjacent to the Salton Sea, Southern California. Combined with previous measurements in the polymer gel Carbopol, we obtained an empirical model for the drag coefficient and bounded the conditions under which bubbles overcome the yield stress. Yield stresses typical of mud and basaltic magmas with sub-mm particles can immobilize millimeter to centimeter sized bubbles. At Stromboli volcano, Italy, a vertical yield stress gradient in the shallow conduit may immobilize bubbles with diameter 1 cm and hinder slug coalescence.

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

“…Our measurements describe a relationship between viscosity and shear strain rate similar to those found in previous studies on mud rheology (Figure ). Flow index n obtained for Fiumicino muds are within the range of values found for debris flow and lahar mudflows, 0.22 < n < 0.48 [ Coussot and Piau , ; Bisantino et al , ] and for mud volcanoes, 0.17 < n < 0.71 [ Tran et al , ], indicating a similar degree of shear‐thinning behavior (decrease of viscosity with increasing shear rate) (Figure b). However, Fiumicino mud exhibits lower yield stress and consistency values.…”

“…(b) Computed values of ascent velocities for Fiumicino (FC08‐FC16) and other mud volcanoes (clast density 2.6 g/cm 3 ). Rheological data used for calculations are from Manga and Bonini [] (Apennines), Rudolph and Manga [], and Tran et al [] (Salton Sea). For Lusi mud volcano, no direct rheology measurement is available and estimated values inferred by Tran et al [] have been used.…”

“…In the first equation (Re < 20), the numerical constant in front of Bi is 0.823 [Beaulne and Mitsoulis, 1997;Tabuteau et al, 2007;Tran et al, 2015] and the value of X for n = 0.40 is 1.442 [Dazhi and Tanner, 1985].…”

Rheology of Natural Sediments and Its Influence on the Settling of Dropstones in Hemipelagic Marine Sediment

“…A yield stress becomes apparent in the hemipelagic sediment at a particle concentration of~10% and increases with increasing particle concentration. Figure 2a also shows the yield stress as a function of particle concentration measured in other studies (Coussot & Piau, 1994;Coussot et al, 1996;Huang & García, 1998;Malet et al, 2005;Remaitre et al, 2005;Maciel et al, 2009;Santolo et al, 2010;Blasio et al, 2011;Manga & Bonini, 2012;Jeong, 2013;Yang et al, 2014;Tran et al, 2015). In Figure 2, non-natural sediments are represented with squares.…”

Episodic massive mud eruptions from submarine mud volcanoes examined through topographical signatures

“…The rheology of mud is often described with a nonlinear viscoplastic Herschel-Bulkley model [e.g., Herschel and Bulkley, 1926;Huang and García, 1998]. Although this model is known to fit rheological data of mud over a wide range of shear rates [Nguyen and Boger, 1992;Coussot and Piau, 1994], the flow index approximating the degree of non-Newtonian behavior has a very large range depending on materials of mud flow [Coussot and Piau, 1994;Tran et al, 2015;Vona et al, 2015]. Unlike magmatic volcanoes whose dynamic viscosity of magma has a wide span of values, ∼10 −1 -10 14 Pa s [Hess and Dingwell, 1996;Giordano et al, 2008], the range of dynamic viscosities of the ejecta from mud volcanoes is narrow, ranging over 10 3 -10 6 Pa s based on measurements and laboratory experiments even accounting for a moderate variation in water content [Kopf and Behrmann, 2000;Manga et al, 2009;Rudolph and Manga, 2010], while progressive water dilution makes smaller values [Vona et al, 2015].…”