Spatial and temporal distribution of low frequency volcanic earthquakes in the southern Okinawa Trough back-arc basin

Spatial variations in the frequency-magnitude distribution of earthquakes in the southwestern Okinawa Trough

The relations between the frequency of occurrence and the magnitude of earthquakes are established in the southern Okinawa Trough for 2823 relocated earthquakes recorded during a passive ocean bottom seismometer experiment. Three high b-values areas are identified: (1) for an area offshore of the Ilan Plain, south of the andesitic Kueishantao Island from a depth of 50 km to the surface, thereby...

Temporal and spatial distribution of extreme precipitation indices over the lake Urmia Basin, Iran

Distribution of low-frequency earthquakes accompanying the very low frequency earthquakes along the Ryukyu Trench

This study investigated the activity and distribution of low-frequency earthquakes (LFEs) accompanying the very low frequency earthquakes (VLFEs) in the central and southern Ryukyu Trench. This investigation was based on shortperiod seismometer waveforms obtained by the Japan Meteorological Agency from April 2004 to December 2015. The LFEs were detected using the Envelope Correlation Method, an...

Thematic Article Noble gases in pillow basalt glasses from the northern Mariana Trough back-arc basin

Noble gas concentrations and isotopic compositions have been measured in eight samples of pillow basalt glasses collected from seven different localities along 250 km of the Mariana Trough spreading and rifting axis. The samples have uniform and mid-ocean ridge basalt (MORB)-like He/He values of 9±12 ́ 10 (6.4±8.6 times atmospheric) despite large variations in He. Concentrations of the noble ga...

Peridotites from the Mariana Trough: first look at the mantle beneath an active back-arc basin

Two dives of the DSV Shinkai 6500 in the Mariana Trough back-arc basin in the western Pacific sampled back-arc basin mantle exposures. Reports of peridotite exposures in back-arc basin setting are very limited and the lack of samples has hindered our understanding of this important aspect of lithospheric evolution. The Mariana Trough is a slow-spreading ridge, and ultramafic exposures with asso...