scholarly journals Southward growth of Mauna Loa’s dike-like magma body driven by topographic stress

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bhuvan Varugu ◽  
Falk Amelung
Keyword(s):  
Rift Zone ◽  
Pressure Increase ◽  
Lateral Growth ◽  
Magma Intrusion ◽  
Magma Body ◽  
Mauna Loa ◽  
Vertical Extent ◽  
Eastern Flank ◽  
New Period

AbstractSpace-geodetic observations of a new period of inflation at Mauna Loa volcano, Hawaii, recorded an influx of 0.11 km3 of new magma into it’s dike-like magma body during 2014–2020. The intrusion started after at least 4 years of decollement slip under the eastern flank creating > 0.15 MPa opening stresses in the rift zone favorable for magma intrusion. Volcanoes commonly respond to magma pressure increase with the injection of a dike, but Mauna Loa responded with lateral growth of its magma body in the direction of decreasing topographic stress. In 2017, deformation migrated back, and inflation continued at the pre-2015 location. Geodetic inversions reveal a 8 × 8.5, 10 × 3 and 9 × 4 km2 dike-like magma body during the 2014–2015, 2015–2018 and 2018–2020 periods, respectively, and an average decollement slip of ~ 23 cm/year along a 10 × 5 km2 fault. The evolution of the dike-like magma body including the reduction in vertical extent is consistent with a slowly ascending dike propagating laterally when encountering a stress barrier and freezing its tip when magma influx waned. Overall, the magma body widened about 4.5 m during 2002–2020.

scholarly journals Environments of Crystallization and Compositional Diversity of Mauna Loa Xenoliths

2002 ◽  
Vol 43 (6) ◽  
pp. 963-981 ◽  
Author(s):  
AMY M. GAFFNEY
Keyword(s):  
Rift Zone ◽  
Bulk Composition ◽  
Olivine Gabbro ◽  
Magma Storage ◽  
Mauna Loa ◽  
Ni Content ◽  
Storage Area ◽  
Compositional Variability ◽  
Magma Flux ◽  
Compositional Diversity

Abstract Two picrite flows from the SW rift zone of Mauna Loa contain xenoliths of dunite, harzburgite, lherzolite, plagioclase-bearing lherzolite and harzburgite, troctolite, gabbro, olivine gabbro, and gabbronorite. Textures and olivine compositions preclude a mantle source for the xenoliths, and rare earth element concentrations of xenoliths and clinopyroxene indicate that the xenolith source is not old oceanic crust, but rather a Hawaiian, tholeiitic-stage magma. Pyroxene compositions, phase assemblages and textural relationships in xenoliths indicate at least two different crystallization sequences. Calculations using the pMELTS algorithm show that the two sequences result from crystallization of primitive Mauna Loa magmas at 6 kbar and 2 kbar. Independent calculations of olivine Ni–Fo compositional variability in the plagioclase-bearing xenoliths over these crystallization sequences are consistent with observed olivine compositional variability. Two parents of similar bulk composition, but which vary in Ni content, are necessary to explain the olivine compositional variability in the dunite and plagioclase-free peridotitic xenoliths. Xenoliths probably crystallized in a small magma storage area beneath the rift zone, rather than the large sub-caldera magma reservoir. Primitive, picritic magmas are introduced to isolated rift zone storage areas during periods of high magma flux. Subsequent eruptions reoccupy these areas, and entrain and transport xenoliths to the surface.

Sm–Nd Isotope Systematics of the Cenozoic Sand Deposits in the Muya Depression (Eastern Flank of the Baikal Rift Zone)

2021 ◽  
Vol 499 (2) ◽  
pp. 616-618
Author(s):  
A. B. Kotov ◽  
T. M. Skovitina ◽  
V. P. Kovach ◽  
S. D. Velikoslavinskii ◽  
I. N. Buchnev ◽  
...  
Keyword(s):  
Rift Zone ◽  
Baikal Rift Zone ◽  
Nd Isotope ◽  
Eastern Flank ◽  
Isotope Systematics

Modulation of seismic activity in Kīlauea’s upper East Rift Zone (Hawaiʻi) by summit pressurization

Geology ◽  
2019 ◽  
Vol 47 (9) ◽  
pp. 820-824 ◽  
Author(s):  
Christelle Wauthier ◽  
Diana C. Roman ◽  
Michael P. Poland
Keyword(s):  
Transport System ◽  
Rift Zone ◽  
Wall Rock ◽  
Eruptive Activity ◽  
Magma Intrusion ◽  
Fault Plane Solutions ◽  
Coulomb Stress Changes ◽  
Stress Changes ◽  
Multi Temporal ◽  
Magma System

Abstract Kīlauea Volcano (Hawaiʻi, USA) is underlain by a complex, laterally extensive magmatic plumbing system. Although in recent decades it has mainly erupted through vents along the middle East Rift Zone and summit caldera, eruptions can occur anywhere along its laterally extensive rift zones, as demonstrated by the dramatic eruptive activity of 2018. Forecasting eruptive activity requires an understanding of whether an episode of volcano-seismic unrest at Kīlauea and similar volcanoes is caused directly at the edges of an active intrusion or reservoir, or in a volume of wall rock at a distance from the intrusion. Seismic unrest in Kīlauea’s upper East Rift Zone (UERZ) has to date been interpreted as the result either of magma intrusion in this region of the volcano or of stresses due to seaward flank migration. However, recent observations suggest that UERZ seismicity may result from variable pressurization of Kīlauea’s summit magma system. We analyze seismic and deformation (multi-temporal interferometric synthetic aperture radar [InSAR] and GPS) data during a period of variable summit deformation and UERZ seismicity in mid- to late 2007 and calculate Coulomb stress changes on UERZ faults due to modeled summit inflation or deflation. UERZ seismicity during our study period can be explained entirely by stresses arising from pressure changes within Kīlauea’s summit reservoirs. Furthermore, a comparison of UERZ fault plane solutions (FPSs) calculated for this study to published UERZ FPSs for previous periods suggests that the UERZ has undergone a transition from a mechanically strong, discontinuous, and immature magma transport system to a mature, mechanically weak, and fully connected transport system over the course of the 1983–2018 eruption.

scholarly journals Tomographic image of P-velocity structure beneath Kilauea's East Rift Zone and South Flank: Seismic evidence for a deep magma body

2001 ◽  
Vol 28 (2) ◽  
pp. 375-378 ◽  
Author(s):  
Florian Haslinger ◽  
Clifford Thurber ◽  
Megan Mandernach ◽  
Paul Okubo
Keyword(s):  
Rift Zone ◽  
Velocity Structure ◽  
Tomographic Image ◽  
Magma Body

scholarly journals Explosive activity on Kīlauea’s Lower East Rift Zone fuelled by a volatile-rich, dacitic melt

2022 ◽  
Author(s):  
Penny Wieser ◽  
Marie Edmonds ◽  
Cheryl Gansecki ◽  
John Maclennan ◽  
Frances Jenner ◽  
...  
Keyword(s):  
Fractional Crystallization ◽  
Melt Inclusions ◽  
Rift Zone ◽  
Major Element ◽  
High Viscosity ◽  
Explosive Eruptions ◽  
Strombolian Activity ◽  
Magma Body ◽  
Incompatible Elements ◽  
Glass Compositions

Magmas with matrix glass compositions ranging from basalt to dacite erupted from a series of 24 fissures in the first two weeks of the 2018 Lower East Rift Zone (LERZ) eruption of Kīlauea Volcano. Eruption styles ranged from low spattering and fountaining to strombolian activity. Major element trajectories in matrix glasses and melt inclusions hosted by olivine, pyroxene and plagioclase are consistent with variable amounts of fractional crystallization, with incompatible elements (e.g., Cl, F, H2O) becoming enriched by 4-5 times as melt MgO contents evolve from 6 to 0.5 wt%. The high viscosity and high H2O contents (~2 wt%) of the dacitic melts erupting at Fissure 17 account for the explosive Strombolian behavior exhibited by this fissure, in contrast to the low fountaining and spattering observed at fissures erupting basaltic to basaltic-andesite melts. Saturation pressures calculated from melt inclusions CO2-H2O contents indicate that the magma reservoir(s) supplying these fissures was located at ~2-3 km depth, which is in agreement with the depth of a dacitic magma body intercepted during drilling in 2005 (~2.5 km) and a seismically-imaged low Vp/Vs anomaly (~2 km depth). Nb/Y ratios in erupted products are similar to lavas erupted between 1955-1960, indicating that melts were stored and underwent variable amounts of crystallization in the LERZ for >60 years before being remobilized by a dike intrusion in 2018. We demonstrate that extensive fractional crystallization generates viscous and volatile-rich magma with potential for hazardous explosive eruptions, which may be lurking undetected at many ocean island volcanoes.

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