Focal depth, magnitude, and frequency distribution of earthquakes along oceanic trenches

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...

Global frequency of magnitude 9 earthquakes

For decades seismologists have sought causal relationships between maximum earthquake sizes and other properties of subduction zones, with the underlying notion that some subduction zones may never produce a magnitude ~9 or larger event. The 2004 Andaman Mw 9.2 earthquake called into question such ideas. Given multicentury return times of the greatest earthquakes, ignorance of those return time...

Focal Mechanism Determination Using High Frequency Waveform Matching and Its Application to Small Magnitude Induced Earthquakes

We present a new method using high frequency full waveform information to determine the focal mechanisms of small, local earthquakes monitored by a sparse surface network. During the waveform inversion, we maximize both the phase and amplitude matching between the observed and modeled waveforms. In addition, we use the polarities of the first P-wave arrivals and the average S/P amplitude ratios...

Impact of Channel-like Erosion Patterns on the Frequency Magnitude Distribution of Earthquakes

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...