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Comment on “Origin of temporal changes of inner-core seismic waves” by Yang and Song (2020)

Global variations of Earth's 520- and 560-km discontinuities

1. We perform a global survey of the 520- and 560-km mantle discontinuity by analyzing SS precursors. 2. Our observations confirm the global existence of the 520-km discontinuity. 3. Depth variations of the 520-km discontinuity correlate with the mid-MTZ temperature. 4. Compositional heterogeneity also contributes to the 520-km discontinuity topography. 5. A 560-km discontinuity is sporadically detected in subduction zones and mantle upwells. 6. The existence of the 560-km discontinuity may imply localized Ca-enrichment in the mid-MTZ possibly related to the recycling of oceanic crust.

The Generic Mapping Tools version 6

The Generic Mapping Tools (GMT) software is ubiquitous in the Earth and ocean sciences. As a cross‐platform tool producing high‐quality maps and figures, it is used by tens of thousands of scientists around the world. The basic syntax of GMT scripts …

Temporal change of seismic Earth's inner core phases: inner core differential rotation or temporal change of inner core surface?

We discuss the question whether inner core (IC) differential rotation or temporal change of the IC surface provides a consistent interpretation for temporal changes of the IC‐related phases and their coda. While temporal change of the IC surface is …

Complex and diverse rupture processes of the 2018 Mw 8.2 and Mw 7.9 Tonga-Fiji deep earthquakes

Deep earthquakes exhibit strong variabilities in their rupture and aftershock characteristics, yet their physical failure mechanisms remain elusive. The 2018 Mw 8.2 and Mw 7.9 Tonga-Fiji deep earthquakes, the two largest ever recorded in this …

Source characteristics of North Korea's 3 September 2017 nuclear test

By using an on-site collapse event as a reference and eliminating path effects of seismic-wave propagation, we constrain source characteristics of North Korea's 3 September 2017 nuclear test. In the framework of a complete source model for an …

Triggered seismicity after North Korea's 3 September 2017 nuclear test

The 3 September 2017 nuclear test conducted by the Democratic People's Republic of Korea was followed by a series of small seismic events. In this study, we conduct a survey of small seismic events from 1 May 2017 to 25 April 2018 near North Korea's …

Collapse and earthquake swarm after North Korea's 3 September 2017 nuclear test

1. We present high-precision locations and detailed source information of four small seismic events following North Korea's 2017 nuclear test. 2. The first event is an on-site collapse 440 m northwest of the test site and best explained by a near vertical single force. 3. The later events are an earthquake swarm located 8.4 km north of the test site with a focal depth of at least 2.4 km.

Seismic structure and dynamic process of the Earth's inner core and its boundary

Modern seismology has revealed complex structures of the Earth's inner core and its boundary. The interior of the Earth’s inner core exhibits both velocity and attenuation anisotropy, and hemispherical variations of velocity, attenuation and …

Seismological evidence for a localized mushy zone at the Earth’s inner core boundary

Although existence of a mushy zone in the Earth's inner core has been hypothesized several decades ago, no seismic evidence has ever been reported. Based on waveform modeling of seismic compressional waves that are reflected off the Earth's inner …