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The Guerrero seismic gap is presumed to be a major source of seismic and tsunami hazard along the Mexican subduction zone. Until recently, there were limited observations at the shallow portion of the plate interface offshore Guerrero, so we deployed instruments there to better characterize the extent of the seismogenic zone. Here we report the discovery of episodic shallow tremors and potential slow slip events in Guerrero offshore. Their distribution, together with that of repeating earthquakes, seismicity, residual gravity and bathymetry, suggest that a portion of the shallow plate interface in the gap undergoes stable slip. This mechanical condition may not only explain the long return period of large earthquakes inside the gap, but also reveals why the rupture from past M

This study presents new seismic imaging of the Andean subduction zone through P‐wave hybrid finite‐frequency and ray‐theoretical tomography. We measured both differential and absolute traveltimes using broadband seismic waveforms from stations in an array of ocean‐bottom seismographs near the Chile Triple Junction (CTJ) and stations within 30° of the array. These data were combined with the global traveltime data set to obtain a global P‐wave velocity structure with a focus on central to southern South America. The new tomographic image showed the Nazca slab geometry as a continuous fast anomaly, which is consistent with seismic activity and prior slab models. Furthermore, two notable structures were observed: a broad extension of the fast anomaly beneath the Nazca slab at 26–35°S and a slow anomaly east of the CTJ. The checkerboard resolution and recovery tests confirmed the reliability of these large‐scale features. The fast anomaly, isolated from the Nazca slab, was interpreted as a relic Nazca slab segment based on its strong amplitude and spatial coincidence with the current Pampean and past Payenia flat slab segments. The slow anomaly near the CTJ was consistent with the previously inferred extent of the Patagonian slab window. Moreover, the active adakitic volcanoes are aligned with the southern edge of the anomaly, and the plateau basalts are located within the anomaly. Our model showed that the slow anomaly extended to a depth of up to 250 km, suggesting a depth limit that the asthenospheric window can influence. Plain Language Summary: The western margin of South America is one of the largest subduction zones on the Earth and has provided insights into the subduction dynamics of relatively young oceanic plates. We developed a new seismic P‐wave velocity model beneath the Central to Southern South America. Using broadband seismograms, we measured differential traveltimes between two stations by cross‐correlation method and picked P‐wave onsets, and performed tomographic inversion in combination with the global traveltime data from the International Seismological Centre catalog. Our model shows mantle structure to the uppermost part of the lower mantle at a depth of ∼1,000 km. The geometry of the Nazca slab in our model agrees well with other seismic imagings and slab models. Beneath the Nazca slab, a fast velocity anomaly was observed and interpreted as a relic Nazca slab segment. Moreover, strong, slow anomalies in the upper mantle were observed to be located on east side of where the actively spreading Chile Ridge is subducting. The extent of the anomalies, and comparison with volcanism, suggest that the influence of the asthenospheric window extends to a depth of up to 250 km. Key Points: The results of a P‐wave teleseismic tomography study of the central to southern Andean subduction zones are presentedA fast‐velocity anomaly beneath the Nazca slab was revealed and interpreted as a relic Nazca slab segmentA slow‐velocity anomaly associated with the slab window was observed, constraining the maximum depth the asthenospheric window affects [ABSTRACT FROM AUTHOR]

Makito Miyake,1 Nobutaka Nishimura,1,2 Takuto Shimizu,1,3 Mikiko Ohnishi,4 Masaomi Kuwada,4 Yoshitaka Itami,5 Takeshi Inoue,5 Kenta Ohnishi,6 Yoshihiro Matsumoto,6 Takanori Yoshida,7 Yoshihiro Tatsumi,8 Masatake Shinohara,9 Shunta Hori,1 Yosuke Morizawa,1 Daisuke Gotoh,1 Yasushi Nakai,1 Satoshi Anai,1 Kazumasa Torimoto,1 Katsuya Aoki,1 Tomomi Fujii,10 Nobumichi Tanaka,1,11 Kiyohide Fujimoto1 1Department of Urology, Nara Medical University, Kashihara, Nara, 634-8522, Japan; 2Department of Urology, Okanami General Hospital, Iga, Mie, Japan; 3Department of Urology, Saiseikai Chuwa Hospital, Nara, Japan; 4Department of Urology, Matsusaka Chuo General Hospital, Matsusaka, Mie, Japan; 5Department of Urology, Nara Prefecture General Medical Center, Nara, Japan; 6Department of Urology, Hoshigaoka Medical Center, Hirakata, Osaka, Japan; 7Department of Urology, Tane General Hospital, Osaka, Japan; 8Department of Urology, JCHO Yamato Koriyama Hospital, Koriyama, Nara, Japan; 9Department of Urology, Osaka Gyoumeikan Hospital, Osaka, Japan; 10Department of Diagnostic Pathology, Nara Medical University, Kashihara, Nara, 634-8522, Japan; 11Department of Prostate Brachytherapy, Nara Medical University, Kashihara, Nara, 634-8522, JapanCorrespondence: Makito Miyake, Department of Urology, Nara Medical University, 840 Shijo-cho, Nara, 634-8522, Japan, Tel +81-744-22-3051 (ext 2338), Fax +81-744-22-9282, Email makitomiyake@yahoo.co.jpPurpose: The treatment landscape for advanced, unresectable, or metastatic urothelial carcinoma (aUC) has shifted substantially since the advent of immune checkpoint inhibitors (ICIs). We investigated the extent to which pembrolizumab therapy is superior to conventional chemotherapy as a second-line treatment.Patients and Methods: A multicenter-derived database registered 454 patients diagnosed with aUC between 2008 and 2020. Of these, 94 patients (21%) who received second-line pembrolizumab and 75 (17%) who received second-line chemotherapy but never received third-line or later ICI therapy were included. We compared overall survival (OS) from the initial date of first-line chemotherapy between two groups by adjusting for prognostic factors through propensity score matching (PSM) and inverse probability of treatment weighting (IPTW). The IPTW-adjusted hazard ratio and 95% confidence interval were estimated using a multivariate Cox regression analysis. To identify patients who were more likely to benefit from second-line pembrolizumab than from chemotherapy, we performed a subgroup analysis for OS with an IPTW-adjusted model.Results: The PSM-adjusted comparison showed a significant improvement in the prognosis with second-line pembrolizumab use (P = 0.01). The OS benefit with the advent of pembrolizumab was 8 months (18 months vs 26 months). Multivariable analyses using IPTW adjustment demonstrated that lymph node metastasis (P = 0.001), lung metastasis (P = 0.013), and bone metastasis (P = 0.003) were poor independent prognostic factors, and pembrolizumab use (P = 0.021) was a favorable independent prognostic factor. Subgroup analyses revealed that pembrolizumab was associated with survival benefits over chemotherapy in all subgroups, including young patients (age < 70 years), those who received radical surgery, and those without visceral metastasis.Conclusion: We demonstrated a significant improvement in prognosis after the advent of pembrolizumab for patients with aUC. ICIs should not be restricted based on patient characteristics.Keywords: urinary bladder neoplasms, immunotherapy, chemotherapy, survival, propensity score