Recent News

  • Apr. 27, 2018: Our seismic analysis reveals that North Korea’s 3 September 2017 nuclear test has resulted in an on-site collapse toward the nuclear test center, and possibly triggered an earthquake swarm ~8.4 km north of the test site. This paper is now available on Geophysical Research Letters.

  • Mar. 12, 2018: Dongdong Tian is awarded the Outstanding Graduate Student Award from University of Science and Technology of China.

  • Nov. 30, 2017: Dongdong Tian is awarded the 2017 CGU Outstanding Student Paper Award for his presentation at the 2017 CGU annual meeting.

  • Nov. 20, 2017: Dongdong Tian is awarded the National Scholarship for Doctoral Students from the Ministry of Education, China.

  • Aug. 1, 2017: We present the first seismological evidence for a localized mushy zone across the Earth’s inner core boundary beneath southwest Okhotsk Sea. This paper is now available on Nature Communications.

Researches

Inner Core Boundary

Use pre-critically reflected PKiKP waves to study the fine-scale structure of the Earth’s inner core boundary.

North Korea Nuclear Tests

High-precision locations and source characteristics of North Korea’s nuclear tests and associated small seismic events.

Selected Publications

North Korea’s 3 September 2017 nuclear test was followed by several small seismic events, with one eight‐and‐a‐half minutes after the test and three on and after 23 September 2017. Seismic analysis reveals that the first event is a near vertical on‐site collapse toward the nuclear test center from 440 ± 260 m northwest of the test site, with its seismic source best represented by a single force with a dip angle of 70°–75° and an azimuth of ~150°, and the later events are an earthquake swarm located 8.4 ± 1.7 km north of the test site within a region of 520 m, with a focal depth of at least 2.4 km and a focal mechanism of nearly pure strike slip along the north‐south direction with a high dip angle of 50°–90°. The occurrence of the on‐site collapse calls for continued monitoring of any leaks of radioactive materials from the test site.
Geophysical Research Letters, 2018

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 core boundary, here we present seismic evidence for a localized 4–8 km thick zone across the inner core boundary beneath southwest Okhotsk Sea with seismic properties intermediate between those of the inner and outer core and of a mushy zone. Such a localized mushy zone is found to be surrounded by a sharp inner core boundary nearby. These seismic results suggest that, in the current thermo-compositional state of the Earth’s core, the outer core composition is close to eutectic in most regions resulting in a sharp inner core boundary, but deviation from the eutectic composition exists in some localized regions resulting in a mushy zone with a thickness of 4–8 km.
Nature Communications, 2017

Publications

. Collapse and earthquake swarm after North Korea's 3 September 2017 nuclear test. Geophysical Research Letters, 2018.

PDF Project

. Seismic structure and dynamic process of the Earth's inner core and its boundary. Chinese Journal of Geophysics (in Chinese), 2018.

PDF Project

. Microseismic sources during Hurricane Sandy. Journal of Geophysical Research: Solid Earth, 2015.

PDF

. A new method for earthquake depth determination: stacking multiple-station autocorrelograms. Geophysical Journal International, 2014.

PDF

Recent & Upcoming Talks

Resources

Softwares &
Documentations &
Websites

Softwares

  • HinetPy: A python package to request and process seismic waveform data from Hi-net.

Documentations

Websites

Professional Services

Awards & Honors

  • 2018: Outstanding Graduate Student, University of Science and Technology of China, China [top 15%]
  • 2017: Outstanding Student Paper Award, 2017 Annual Meeting of Chinese Geoscience Union, China
  • 2017: National Scholarship for Doctoral Students, Ministry of Education, China [top 5%]
  • 2014: Guanghua Scholarship for Graduate Students, Guanghua Education Fund, China
  • 2010: Guanghua Scholarship for Undergraduate Students, Guanghua Education Fund, China
  • 2009: Outstanding Volunteer, University of Science and Technology of China, China

Contact

  • dongzhi@mail.ustc.edu.cn
  • Room 1127, Research Building, University of Science and Technology of China, No. 96, Jinzhai Road, Hefei, Anhui 230026, China.