S U M M A R Y Volcanoes usually show signs of unrest before an eruption. Establishing physical controls on the duration of precursory activity, that is run-up time, could improve understanding of the dynamics of magma ascent from a shallowmagma reservoir to the surface. Another observable indicative of eruption dynamics is the interevent repose time, that is, the time betweenmagmatic eruptions....

[1] Thermal infrared (TIR) data from the MASTER airborne imaging spectrometer were acquired over Mount St. Helens in Sept and Oct, 2004, before and after the onset of recent eruptive activity. Pre-eruption data showed no measurable increase in surface temperatures before the first phreatic eruption on Oct 1. MASTER data acquired during the initial eruptive episode on Oct 14 showed maximum tempe...

The youngest volcanism of the Ecuadorian Volcanic Front (Western Cordillera) is mainly dominated by highly explosive events, including growth and violent destruction lava domes, formation thick pyroclastic sequences. Deposits associated with such eruptive dynamics have been identified at Iliniza, a compound volcano located in Western Cordillera poorly defined evolutionary history. We present fi...

Abstract An electrical resistivity model beneath Azumayama Volcano, NE Japan, is explored using magnetotelluric method to probe the magma/hydrothermal fluid distribution. one of most concerning active volcanoes capable producing a potential eruption triggered by 2011 Tohoku-Oki Earthquake. The three-dimensional reveals conductive magma reservoir (< 3 ?m) at depths 3–15 km below sea level (bs...

New 40Ar/39Ar ages and paleomagnetic data are presented from a wide range of ignimbrites lava flows the region east Atacama Desert in northern Chilean part Central Volcanic Zone Andes. Eight dacitic to rhyolitic ignimbrites, 12 one shallow intrusion were dated by incremental heating method, first reported for these units. Ignimbrites age 4.2 Ma 0.5 Ma, with ~100 km3 Puripicar ignimbrite at 4.18...

Llallagua is one of the world's biggest tin deposits and part metallogenic Bolivian Tin Belt, which occurs in inner arc Central Andes. The deposit formed through emplacement a subvolcanic porphyry stock, intermediate dacitic to rhyodacitic composition, metasomatism, hydrothermal mineralization. subject well-established geochronologic controversy that includes contradictory ages (≈40 20 Ma) from...

The subaerial surface of Koolau volcano is composed of lavas that define the distinctive endmember composition for Hawaiian shield lavas, known as the Koolau component, now designated as the Makapuustage. The geochemical characteristics of lavas recovered by the Koolau Scientific Drilling Project (KSDP) show that this distinctive composition forms a <300-m thick veneer. Below this veneer, from ...

The 3.22-3.10 Ga old Moodies Group, uppermost unit of the Swaziland Supergroup in the Barberton Greenstone Belt (BGB), is the oldest exposed, well-preserved quartz-rich sedimentary sequence on earth. It is preserved in structurally separate blocks in a heavily deformed fold-and-thrust belt. North of the Inyoka Fault, Moodies strata reach up to 3700 m in thickness. Detailed mapping, correlation ...

We present a quantitative assessment of the thermal and dynamic response of an amphibolitic lower crust to the intrusion of basaltic dike swarms in an arc setting. We consider the effect of variable intrusion geometry, depth of intrusion, and basalt flux on the production, persistence, and interaction of basaltic and crustal melt in a stochastic computational framework. Distinct melting and mix...

we present new whole major and trace elements data for a suite of adakitic dacite to rhyolite rocks from the sahand region. these rocks formed in the pliocene to pleistocene during the the collision between the arabian and eurasian plates following subduction of neo–tethys ocean. these subvolcanic intrusions were emplaced into late cretaceous and eocene sedimentary، volcano–clastic and volcanic...