Author: epssadmin
Date: 1/15/2026
Time: 12:00 – 1:00 pm
Location: 3853 Slichter Hall
Presented By: Prof. Man Hoi Lee – University of Hong Kong
Abstract:
In our Solar System, there are numerous mean-motion resonances for the minor bodies and satellites, but there are no mean-motion resonances between the planets. The first mean-motion resonance in an extrasolar planetary system – the 2:1 resonance between two Jupiter-mass planets around the star GJ 876 – was discovered in 2001. Since then, an increasing number of pairs of planets in or near mean-motion resonances and resonant chains of three or more planets have been detected. I will discuss the dynamics of these systems and the constraints that they provide on the formation and dynamical evolution of planets. Topics will include high-order mean-motion resonances in the HD 202206 and nu Ophiuchi systems and the formation of resonant chains near the inner edge of protoplanetary disks.
A new study led by Professor Lingsen Meng and Dr. Liuwei Xu (UCLA Department of Earth, Planetary, and Space Sciences) reveals that the devastating 2025 Mandalay, Myanmar earthquake (Mw 7.7) produced one of the fastest and longest earthquake ruptures ever recorded on land.
The research, published in Science on October 29, 2025, shows that the earthquake ruptured more than 530 kilometers along the Sagaing Fault, with a 450-kilometer supershear segment that propagated faster than the speed of seismic shear waves—an extremely rare phenomenon.
Using global seismic data, satellite radar, and optical imagery, the team reconstructed the rupture in unprecedented detail. Their findings highlight how fault geometry, long-term stress accumulation, and contrasting rock properties combined to enable the exceptional rupture speed, offering new insights into how devastating earthquakes evolve in continental regions.
🧭 Read the paper: Science — Bimaterial Effect and Favorable Energy Ratio Enable Supershear Rupture in the 2025 Myanmar Quake
📰 Read the UCLA press release: UCLA Newsroom — Why the 2025 Myanmar Earthquake Happened and What It Reveals About Fault Dynamics
(Image: Cover of the October 29, 2025 issue of Science featuring studies of the 2025 Myanmar earthquake)
Lecturer
This new SpinLab video shows the Newton’s Bucket experiment in which the free surface of water in a rotating tank takes on a paraboloidal shape. Made by UCLA undergraduate Ryan Landayan, it is a beautiful realization of a classic experiment that was discussed in great detail by Isaac Newton and his colleagues, and is still taught in fluid dynamics courses throughout the world.