کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4678139 1634831 2011 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Shallow seismicity and tectonics of the central and northern Lau Basin
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علوم زمین و سیاره ای (عمومی)
پیش نمایش صفحه اول مقاله
Shallow seismicity and tectonics of the central and northern Lau Basin
چکیده انگلیسی

The Lau basin is an active backarc comprising several spreading centers and microplates rapidly evolving in time. As such, crustal earthquakes within the Lau Basin derive from intrabasin tectonic, volcanic, and hydrothermal sources. Because of high mantle attenuation, small earthquakes from the basin are seldom recorded on land seismographs and it has been difficult to study the pattern of crustal seismicity. However, the 1994 LABATTS ocean bottom seismograph experiment in the Lau basin recorded more than 100,000 local T- and body phases allowing for a detailed examination of basin seismotectonics. Nearly 1000 events are located within the basin proper, with another 2000 associated with the forearc and the aseismic front. We identify two previously undocumented tectonic features, a triple junction in the northwestern basin and a nanoplate in the central Lau basin. The single most seismically active feature within the Lau basin is the Lau extensional transform zone (LETZ) just north of the Central Lau Spreading Center. Significant seismicity also occurs near the northern extension of the Eastern Lau Spreading Center and along a southeast extension of the LETZ delineating the boundary of a previously unknown nanoplate. Swarm activity is common in the backarc basin and dominates regions associated with actively reorganizing tectonics. We see no evidence of deformation along the southern boundary of the Niuafo'ou microplate, where 4.5 cm/yr of strain is predicted. It is possible that the plate boundary extends eastward from the Fonualei rift (FR) tip towards the trench creating a Niuatoputapu–Tonga plate division rather than westward implied by the currently accepted Niuafo'ou–Tonga plate system, but more data are necessary from the FR to test that hypothesis. Instead, we suggest that the Niuafo'ou–Tonga pole is ~ 1.5° further north than previously proposed, reducing the predicted strain in this region to < 2 cm/yr.

Research highlights
► Delineation of small tectonic plates making up northern Lau basin.
► Discovery of nanoplate in central Lau basin.
► Swarm activity associated with evolving plate boundaries.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Earth and Planetary Science Letters - Volume 304, Issues 3–4, 15 April 2011, Pages 538–546
نویسندگان
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