Qi Ou

Dr. Qi Ou


Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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9 June 2022 in Journal of Geophysical Research: Solid Earth
Verified
Journal Article
Open access
QOQi Ou
Qi Ou
SDSimon Daout
Simon Daout
JWJ. R. Weiss
J. R. Weiss
LSLin Shen
Lin Shen
MLMilan Lazecky
Milan Lazecky
BPB. E. Parsons
B. E. Parsons
The launches of the Sentinel‐1 synthetic aperture radar satellites in 2014 and 2016 started a new era of high‐resolution velocity and strain rate mapping for the continents. However, multiple challenges exist in tying independently processed velocity data sets to a common reference frame and producing high‐resolution strain rate fields. We analyze Sentinel‐1 data acquired between 2014 and 2019 over the northeast Tibetan Plateau, and develop new methods to derive east and vertical velocities with ∼100 m resolution and ∼1 mm/yr accuracy across an area of 440,000 km2. By implementing a new method of combining horizontal gradients of filtered east and interpolated north velocities, we derive the first ∼1 km resolution strain rate field for this tectonically active region. The strain rate fields show concentrated shear strain along the Haiyuan and East Kunlun Faults, and local contractional strain on fault junctions, within the Qilianshan thrusts, and around the Longyangxia Reservoir. The Laohushan‐Jingtai creeping section of the Haiyuan Fault is highlighted in our data set by extremely rapid strain rates. Strain across unknown portions of the Haiyuan Fault system, including shear on the eastern extension of the Dabanshan Fault and contraction at the western flank of the Quwushan, highlight unmapped tectonic structures. In addition to the uplift across most of the lowlands, the vertical velocities also contain climatic, hydrological or anthropogenic‐related deformation signals. We demonstrate the enhanced view of large‐scale active tectonic processes provided by high‐resolution velocities and strain rates derived from Sentinel‐1 data and highlight associated wide‐ranging research applications.

13 August 2020 in Journal of Geophysical Research: Solid Earth
Verified
Journal Article
Open access
PDF file
QOQi Ou
Qi Ou
GKG. Kulikova
G. Kulikova
JYJ. Yu
J. Yu
AEA. Elliott
A. Elliott
BPB. Parsons
B. Parsons
RWR. Walker
R. Walker
Reported magnitudes ranging between 7.8 and 8.7 highlight a confusion about the true size of the 1920 Haiyuan earthquake, the largest earthquake recorded in the northeast Tibetan Plateau. We compiled a global data set of previously unlooked‐at historical seismograms and performed modern computational analyses on the digitized seismic records. We found the epicenter to be near Haiyuan town and obtained a moment magnitude of MW=7.9±0.2. Following traditional approaches, we obtained mB=7.9±0.3 with data from 21 stations and MS(20)=8.1±0.2 with data from three stations. Geomorphologically, we mapped the surface rupture and horizontal offsets on high‐resolution Pleiades satellite and drone imagery that covered the entire western and middle sections of the 1920 Haiyuan earthquake rupture and compiled offsets reported on the eastern section from field measurements in the 1980s. Careful discrimination between single‐event and cumulative offsets suggests average horizontal slips of 3.0±1.0 m on the western section, 4.5±1.5 m on the middle section, and 3.5±0.5 m on the eastern section, indicating a total moment magnitude of MW=7.8±0.1. Thus, the seismological and geomorphological results agree within the uncertainties, a weighted average giving a moment magnitude of MW=7.9±0.2 for the 1920 Haiyuan earthquake. It is likely that earthquake magnitudes based on the historical M were systematically overestimated.

15 November 2022 in Journal of Geophysical Research: Solid Earth
Verified
Journal Article
Open access
JFJin Fang
Jin Fang
QOQi Ou
Qi Ou
TWTim Wright
Tim Wright
RORyo Okuwaki
Ryo Okuwaki
RARuth M. J. Amey
Ruth M. J. Amey
YMYasser Maghsoudi
Yasser Maghsoudi
In the continents, the importance of earthquakes that occur away from major block‐bounding faults is still debated. The 21 May 2021 MW ∼ 7.4 Maduo earthquake occurred on a secondary fault away from previously‐identified major block boundaries. Here we use 7 years of Sentinel‐1 Interferometric Synthetic Aperture Radar (InSAR) time series (between October 2014 and November 2021) to determine the distribution of coseismic slip and early postseismic afterslip following the Maduo earthquake, and the preceding interseismic strain accumulation. We devised a 13‐segment 3‐D fault geometry constrained by the SAR range offsets and the distribution of relocated aftershocks and used a Bayesian method incorporating von Karman regularization to solve for coseismic slip and afterslip models. We also used teleseismic waveforms as a standalone inversion to show the rupture evolution in space and time during the earthquake, finding that it propagates bilaterally with three notable rupture episodes. Our preferred coseismic self‐similar slip model shows a moderate shallow slip deficit, with the majority of moment release occurring in the depth interval of 1–10 km. The coseismic slip deficit is taken up in part by afterslip at shallow (10 km depths where afterslip grows logarithmically with time. We suggest that this heterogeneity is likely controlled by spatial variations in fault friction related to lithology. We discuss the implications for seismic hazard away from major tectonic block boundaries in light of our observations of the earthquake cycle on this intrablock fault.

3 October 2024 in Geophysical Research Letters
Verified
Journal Article
Open access
JFJin Fang
Jin Fang
TWTim Wright
Tim Wright
KJKaj M. Johnson
Kaj M. Johnson
QOQi Ou
Qi Ou
RSRichard Styron
Richard Styron
GZGang Zheng
Gang Zheng
Fault slip rates estimated from geodetic data are being integrated into seismic hazard models. The standard approach requires modeling velocities and relative (micro‐)plate motions, which is challenging for fault‐based models. We present a new approach to directly invert strain rates to solve for slip rates and distributed strain simultaneously. We generate velocity and strain rate fields over the southeastern Tibetan Plateau, utilizing Sentinel‐1 Interferometric Synthetic Aperture Radar data spanning 2014–2023. We derive slip rates using block modeling and by inverting strain rates. Our results show a partitioning between localized strain on faults and distributed deformation. The direct inversion of strain rates matches the geodetic data best when incorporating distributed moment sources, accounting for a similar proportion to on‐fault sources. The direct strain methodology also aligns best with the independent geological slip rates, especially near fault tips. As high‐resolution strain rate fields become increasingly available, we recommend direct inversion as the preferred practice.

29 January 2026 in Science
Verified
Journal Article
Closed access
TWTim Wright
Tim Wright
GHG. A. Houseman
G. A. Houseman
JFJ. Fang
J. Fang
YMYasser Maghsoudi
Yasser Maghsoudi
AHAndrew Hooper
Andrew Hooper
DWD. Wang
D. Wang
Understanding the key mechanisms that control the tectonic deformation of the continents remains a fundamental challenge in geodynamics. We present a high-resolution geodetic velocity field of the Tibetan Plateau, which shows that a few major strike-slip fault systems separate regions of more uniformly distributed deformation. We suggest that focused strain on major fault systems is enabled by relatively low-viscosity ductile shear zones extending through the lithosphere beneath the seismically active fault planes. Simple model calculations show that high slip rates on the Kunlun Fault enable east-west extension to be distributed broadly across the relatively weak southern and central Tibetan Plateau. Activation of the Kunlun fault in the Miocene at the same time as the onset of rifting in the north-south grabens suggests a causal relationship.

7 January 2026 in EarthArXiv
Verified
Preprint
Open access
PDF file
JEJohn Elliott
John Elliott
JFJin Fang
Jin Fang
MLMilan Lazecky
Milan Lazecky
YMYasser Maghsoudi
Yasser Maghsoudi
QOQi Ou
Qi Ou
TWTim Wright
Tim Wright
Surface velocities and strain rates from satellite geodesy have become essential tools for understanding the distribution of tectonic deformation, faulting and seismic hazard. However, across large regions of distributed continental deformation, such as the Alpine-Himalayan Belt, data are only sparsely available. While previous studies have mainly used spatially sparse GNSS to measure deformation at such large scales, these approaches cannot characterize shorter wavelength features of deformation in many places. We use Sentinel-1 radar images acquired during 2016-2024 to provide trans-national average surface velocities and time series at 1 km spatial resolution stretching a distance of over 11,000 km from south-western Europe to eastern China, covering an area more than 20 million square kilometres. We produce the velocity field by combining data from over 222,000 Sentinel-1 SAR images with a new belt-wide compilation of GNSS velocities, all combined in a consistent Eurasian reference frame. Horizontal strain rates are derived from gradients of the velocity field, yielding near-continuous spatial deformation information over the entirety of the largest deforming region on the planet. The horizontal velocities and strains are dominated by tectonic deformation, which has a bimodal behaviour -- focused on major faults but distributed elsewhere. Shorter-wavelength vertical velocities are dominated by non-tectonic processes, in particular the widespread over-exploitation of groundwater. Our new velocity and strain rates are foundational data sets that reveal the details of how the continents deform for the first time at trans-continental scale.