Podrobnosti záznamu

    Seismic activity around and under Krakatau Volcano, Sunda Arc : constraints to the source region of Island Arc Volcanics
Údaj o odpovědnosti
    Aleš Špičák, Václav Hanuš, Jiří Vaněk
    Hanuš, Václav
    Špičák, Aleš
    Vaněk, Jiří, 1927-
Zdrojový dokument - seriál
    Studia geophysica et geodaetica
    Vol. 46, no. 3
    p. 545-565
    7 obr., 1 tab.
    Obsahuje bibliografické odkazy
    Zkr. název ser.: Stud. geophys. geod. (Praha)
Klasifikační znak
Skupina konspektu
Předmětová skupina
    Benioffova zóna
    vulkán ostrovní
    zemětřesení středně hluboké
    zemětřesný roj
Geografické jméno
Klíčové slovo
Abstrakt (anglicky)
   There is general agreement that calc-alkaline volcanic rocks at convergent plate margins are genetically related to the process of subduction (Ringwood, 1974; Maaloe and Petersen, 1981; Hawkesworth et al, 1997). However, opinions on the mode and site of generation of primary magma for island arc volcanism differ substantially. The site of generation of calc-alkaline magma is thought to be either in the mantle wedge (Plank and Langmuir, 1988; McCulloch and Gamble, 1991) or in the subducting slab (White and Dupre, 1986; Defant and Drummond, 1990; Edwards et al., 1993; Ryan and Langmuir, 1993). We present seismological evidence in favour of the latter concept. A distinctive seismicity pattern around and under the Krakatau volcano was identified during systematic studies of the SE Asian convergent plate margins by means of global seismological data.
   A column-like cluster of events, probably associated with the dynamics of the volcano, is clearly separated from the events in the Wadati-Benioff zone. The accuracy of hypocentral determinations of the events of the cluster does not differ from the accuracy of the events belonging to the subducting slab. The depths of the cluster events vary from very shallow to about 100 km without any apparent discontinuity. On the other hand, there is a pronounced aseismic gap in the Wadati-Benioff zone directly beneath the volcano at depths between 100-150 km. The Krakatau cluster connects this aseismic gap to the volcano at the surface. The pervasive occurrence of earthquakes in the continental wedge between the subducting slab and the Earth surface bears witness to the brittle character of the continental lithosphere and casts doubt on the existence of large-scale melting of mantle material.
   The aseismic gap (Hanuš and Vaněk, 1985), interpreted by us as a partially melted domain occurring in subducted slabs in practically all active subduction zones that reach depths greater than 100 km, is here used as evidence for the location of the primary source region of island arc volcanics in the subducting plate
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
Datum vložení
    5. 12. 2006
Datum importu
    8. 8. 2012