Multi-Array Multi-Phase Back-Projection: Improving the imaging of earthquake rupture complexities

<p><span>We present a back-projection method capable of being parameterized with multiples arrays. The rupture imaging is weighted to restrict uncertainties induced by non-symmetric azimuthal coverage of seismic arrays. The strategy also exploits the differences in time delays between </span><em><span>P</span></em><span> and depth phase (</span><em><span>pP)</span></em><span> waveforms by assuming them as proxies of the rupture that can be simultaneously back-projected. Surprisingly, this helps to improve the final results, even when depth phases overlap with the direct arrivals due to the rupture time exceeding the <em>pP-P</em> delay. Thus, the approach heightens the spatiotemporal resolvability enough to image rupture complexities. The rupture image of two large events demonstrates its robustness. The first one is the 14 November 2007 Mw 7.7 Tocopilla earthquake in northern Chile. The high-frequency rupture (0.5 - 2.0 Hz) encircles two asperities while the short-period energy radiated predominates up-dip of the coseismic slip. We propose the contribution of asperity rupture complexities and along-dip barriers to high-frequency emissions beyond the megathrust frictional structure. The second one is the Mw 7.5 Palu strike-slip earthquake, which occurred on 28 September 2018 in Sulawesi island. The back-projection reveals a prominent supershear rupture at a speed of 4.5 km/s. The result correlates with space geodesy data highlighting the successful recovery of fault structures. Finally, we discuss the potential and challenges of automating this analysis for near-real-time applications</span>, including near-source back-projection with strong-motion data.</p>

Current and Emerging Imaging Techniques in Patients with Genetic Aortic Syndromes

Background Patients with genetic aortic syndromes such as Marfan or Loeys-Dietz syndrome have a decreased life expectancy due to the risk of aortic dissection and rupture. Imaging plays an important role in the acute setting but also in the initial diagnosis and image-based monitoring. In this article, we provide an overview of the most common genetic aortic syndromes and recommended imaging strategies. Furthermore, we highlight modern imaging methods allowing for the quantification of hemodynamic changes in aortic disease. Method This is a narrative review article on genetic aortic syndromes and recommended imaging strategies, where we take into account expert opinions and standard-of-care practices from our own center. Results and Conclusion Radiological imaging plays a key role in the initial diagnosis and surveillance of patients with genetic aortic syndromes. Radiologists contribute significantly to the multi-disciplinary setting of genetic aortic syndromes with knowledge of special features and recommended imaging methods. Accurate measurement of the aorta is crucial, particularly in terms of diameter-based surgical treatment algorithms. Modern imaging methods like 4D-flow MRI and pulse wave velocity have a potential to further improve individualized risk stratification in patients with genetic aortic syndromes. Key points: Citation Format