Phyo Maung Maung

Bio: Phyo Maung Maung is an academic researcher from Nanyang Technological University. The author has contributed to research in topics: Seismic hazard & Monsoon. The author has an hindex of 3, co-authored 4 publications receiving 45 citations.

On the glacial-interglacial variability of the Asian monsoon in speleothem δ18O records.

Abstract: While Asian monsoon (AM) changes have been clearly captured in Chinese speleothem oxygen isotope (δ18O) records, the lack of glacial-interglacial variability in the records remains puzzling. Here, we report speleothem δ18O records from three locations along the trajectory of the Indian summer monsoon (ISM), a major branch of the AM, and characterize AM rainfall over the past 180,000 years. We have found that the records close to the monsoon moisture source show large glacial-interglacial variability, which then decreases landward. These changes likely reflect a stronger oxygen isotope fractionation associated with progressive rainout of AM moisture during glacial periods, possibly due to a larger temperature gradient and suppressed plant transpiration. We term this effect, which counteracts the forcing of glacial boundary conditions, the moisture transport pathway effect.

A 3-D Shear Wave Velocity Model for Myanmar Region

Abstract: Myanmar is located at the eastern margin of the ongoing Indo-Eurasian collision system, has experienced a complex tectonic history and is threatened by a high level of seismic hazard. Here we develop a crustal scale 3-D seismic velocity model of Myanmar, which is not only critical for understanding the regional tectonic setting and its evolution but can also provide the foundation for a variety of seismological studies, including earthquake location determinations, earthquake focal mechanism inversions, and ground motion simulations. We use the newly deployed Earth Observatory of Singapore-Myanmar broadband seismic network and other seismic stations in and around Myanmar to study the station-based 1-D velocity structure through a joint inversion of receiver functions, H/V amplitude ratio of Rayleigh waves, and surface wave dispersion measurements. Our results reveal a highly variable crustal structure across Myanmar region, characterized by a series of N-S trending sedimentary basins, with thicknesses up to ~15 km in central Myanmar and an ~5-km step in the depth of the Moho across the Sagaing-Shan Scarp fault system. We interpolate our station-based 1-D velocity profiles to obtain an integrated 3-D velocity model from southern Bangladesh to Myanmar. Using three regional earthquakes located to the south, within, and north of the seismic network, we show that our proposedmodel performs systematically better than the CRUST 1.0 model for both Pnl waves and surface waves. Our study provides a preliminary community velocity model for the region, with further refinements and interpretations anticipated in the near future.

The January 11, 2018, Mw 6.0 Bago-Yoma, Myanmar Earthquake: A Shallow Thrust Event Within the Deforming Bago-Yoma Range

Abstract: On 11 January 2018 (18:26 UTC), a Mw 60 earthquake occurred approximately 30 km west of the Sagaing Fault in the Bago-Yoma Range (BYR) Using a local broadband seismic network and regional seismic

High-Resolution Anisotropic Prestack Kirchhoff Dynamic Focused Beam Migration

Abstract: Kirchhoff beam migration is a kind of ray-based seismic imaging method boasting the advantages of both high efficiency and high accuracy. In this paper, anisotropic ray tracing will be applied to extend it to an anisotropic seismic imaging method. However, two problems exist in this method for imaging calculation: Firstly, the conventional local plane wave decomposition method has a low computational precision; secondly, the original beam propagator diverges quickly when the propagation distance increases. These two problems can both increase imaging noise, and finally reduce the resolution of the final imaging results. In this paper, the high-resolution anisotropic Kirchhoff dynamic focused beam migration is proposed to solve these two problems. Local plane wave decomposition method considered from the perspective of inversion is employed to obtain higher-quality slant stack data and dynamic focused beam propagator is adopted to control the divergence of beams. Both the anisotropic layer model and Hess model are adopted to test the imaging ability of the new method.

Orbital-scale Asian summer monsoon variations: Paradox and exploration

Abstract: The Asian summer monsoon (ASM) is a vast climate system, whose variability is critical to the livelihoods of billions of people across the Asian continent. During the past half-century, much progress has been made in understanding variations on a wide range of timescales, yet several significant issues remain unresolved. Of note are two long-standing problems concerning orbital-scale variations of the ASM. (1) Chinese loess magnetic susceptibility records show a persistent glacial-interglacial dominated ~100 kyr (thousand years) periodicity, while the cave oxygen-isotope (δ18O) records reveal periodicity in an almost pure precession band (~20 kyr periodicity)—the “Chinese 100 kyr problem”. (2) ASM records from the Arabian Sea and other oceans surrounding the Asian continent show a significant lag of 8–10 kyr to Northern Hemisphere summer insolation (NHSI), whereas the Asian cave δ18O records follow NHSI without a significant lag—a discrepancy termed the “sea-land precession-phase paradox”. How can we reconcile these differences? Recent and more refined model simulations now provide spatial patterns of rainfall and wind across the precession cycle, revealing distinct regional divergences in the ASM domain, which can well explain a large portion of the disparities between the loess, marine, and cave proxy records. Overall, we also find that the loess, marine, and cave records are indeed complementary rather than incompatible, with each record preferentially describing a certain aspect of ASM dynamics. Our study provides new insight into the understanding of different hydroclimatic proxies and largely reconciles the “Chinese 100 kyr problem“ and “sea-land precession-phase paradox”.