We report the first paleoseismic evidence jointly documenting coseismic subsidence and tsunami inundation from the 1730 Chile earthquake (Mw >= 9) and its trans-Pacific tsunami. At Campiche, a former coastal lagoon in Chile's Metropolitan Region, multiproxy stratigraphic, sedimentological, and microfossil data reveal a laterally continuous tsunami sand sheet that extends similar to 2 km inland, sharply disrupts lagoonal mud, and shows an erosional lower contact, rip-up clasts, and mud drapes from waning flow. Accompanying shifts from freshwater to brackish-marine diatom assemblages and the sudden appearance of salt-tolerant plant remains record a persistent increase in tidal influence, indicating coseismic subsidence. Radiocarbon and luminescence ages constrain its deposition to 1698-1782 CE, consistent with historical accounts of the 1730 tsunami and the absence of any other comparable event in the written record. Campiche thus complements previously reported uplift-dominated mid-Holocene records by showing that infrequent, subsidence-generating shallow ruptures-not just deeper, uplift-producing earthquakes-are an integral component of central Chile's megathrust behavior. Remarkably, this paleoseismic archive, formed during a brief window within a similar to 4000-year marine-to-terrestrial transition and preserved in an emergent, semiarid, preservation-limited margin, suggests that similar evidence may exist in other unfavorable settings. Integration of the Campiche record with historical, geophysical, and geodetic data indicates that a shallow slip deficit of similar to 20 m may have accumulated since 1730, consistent with highly coupled shallow asperities, the recent shift from coastal stability to gradual subsidence, and proposed 200-650 yr recurrence intervals for large tsunamis. Taken together, these lines of evidence suggest that Chile's Metropolitan Region now lies within a plausible near-term window for another large tsunamigenic rupture. These findings underscore the need to integrate paleoseismic records and deep-shallow rupture interplay-including infrequent shallow Mw >= 9 events superimposed on more frequent Mw similar to 8 deeper earthquakes-into tsunami-hazard models for Chile and the wider Pacific.

Abstract Jara‐Muñoz et al. (2024), https://doi.org/10.1029/2024gc011541, presented a new reconstruction of the lake level for the transition between paleolake Lisan and the Dead Sea, which prompted further discussion by Torfstein et al. (2025), https://doi.org/10.1029/2024gc011972. We appreciate their interest in our work, although their critique partly relies on inaccurate statements and methodological misconceptions regarding our approach. Our study reconstructs past lake levels using lake‐level index points derived from dated stromatolites and surveyed paleoshorelines corrected for ground deformation. It thus appears that these methodological details may not have been fully considered in their evaluation. Contrary to their claim, earlier data sets were not ignored by us but compared based on a critical assessment. Our systematic approach requires index points with well‐constrained vertical and temporal uncertainties, a condition often not achieved in earlier data sets of lake level histories. While facies data remain important for interpreting lake dynamics, these cannot serve as index points in our reconstruction framework. Based on 89 radiocarbon and U‐series ages, our reconstruction constrains the Lisan highstand to 30–28.5 ka, approximately 5 ka earlier than previously estimated. This discrepancy does not arise from omission but from improved handling of uncertainties and tectonic corrections. The U‐Th dating bias alleged by Torfstein et al. (2025), https://doi.org/10.1029/2024gc011972, to be caused by acid leaching seems to stem from a misunderstanding of our methods. In light of the careful data collection and analysis, our reconstruction remains internally consistent, statistically robust, and fully reproducible, qualities we hope will guide future discussions toward data‐based observations.

Coseismic uplift along convergent margins drives rapid coastal progradation, yet its short-term morpho-stratigraphic response remains poorly documented at human timescales. Here we integrate four complementary high-resolution proxies: satellite-derived shorelines, multi-temporal mapping of the seaward dune vegetation line (SVDL), ground-penetrating radar stratigraphy, and UAV–LiDAR topographic surveys to reconstruct 15 years of post-seismic coastal evolution at Laraquete–Horcones Beach following the 2010 Mw 8.8 Maule earthquake. Pre-seismic records confirm a sediment-starved coast lacking long-term progradation. The earthquake produced an instantaneous shoreline advance of 25 ± 4.9 m, followed by sustained post-seismic SVDL progradation of 45–48 m. This distance closely matches the mean inter-ridge spacing of the adjacent Holocene Laraquete–Carampangue strandplain (48.9 m). GPR data reveal a replicable prograding beach–berm stratigraphic succession (PBF→BBF), locally capped by an aeolian drape, with abrupt landward signal attenuation indicating rapid coastal abandonment and subaerial stabilization. By integrating short-term morphodynamics with subsurface stratigraphy, these results provide the first multi-proxy observational evidence consistent with repeated coseismic uplift driving Holocene strandplain construction along sediment-limited convergent margins, supporting this mechanism as a first-order control in sediment-starved convergent settings. Coseismic uplift thus functions as a recurring tectonic buffer, temporarily offsetting sediment deficits and interseismic subsidence, with implications for coastal resilience under sea-level rise.

Abstract Field observations of past sea-level variations are needed to validate models predicting future sea-level rise. Along tectonically active coasts, separating tectonic and non-tectonic sea-level components is challenging as both have similar amplitudes but necessary to decipher sea-level histories driven by climate forcing. Here, we present a new framework to decipher Holocene sea-level changes using marine terraces–geomorphic features formed by wave erosion of bedrock–mapped with high-resolution LiDAR data and numerical modelling. Applied to 266 sites along 500 km of central Chilean coast, we found that Holocene terrace elevations linearly correlate with Late Pleistocene terrace elevations, evidencing steady-state tectonics over the past 125,000 years. This proof of steady-state uplift allows subtracting tectonic components from Holocene elevations using uplift rates from Pleistocene terraces. We find that during the mid-Holocene, sea level reached 3.18 ± 0.15 m above modern elevation, only 0.33 m below glacial isostatic model predictions with 2·1020 Pa·s mantle viscosity. We validated this relationship by reproducing Holocene terrace elevations using a landscape evolution model and glacial isostatic sea-level curves. Our results suggest that accounting for millennial-scale vertical land motion rates that average many seismic cycles may improve future relative sea-level change projections, highlighting the potential of rocky-shore geomorphology for sea-level research along tectonically active coastlines.

The Central Andes forearc preserves extensive low-relief marine and continental landforms that record long-term margin uplift, yet the timing and driving mechanisms of this deformation remain debated. Here we present eleven new in situ Be-10 exposure ages from high fluvial terraces and four ages from a lower terrace, combined with geomorphic analyses across eight adjacent catchments (29.5-32.5 degrees S), to reassess the chronology and tectonic significance of the degradational surfaces (pediplains). Exposure ages indicate that the high terrace was abandoned between similar to 1 and 2 Ma (Early Pleistocene), while a lower terrace records a subsequent incision phase at similar to 0.4-0.8 Ma. Morphometric analysis reveals a systematic upstream-decreasing pediplain relief pattern that terminates within the surface projection of the 50-55 km slab-depth contour, a region coincident with the downdip limit of megathrust Domain-C and deep coseismic deformation. In peninsular settings, notably the Altos de Talinay, this long-wavelength signal is overprinted by short-wavelength uplift likely related to localized underplating. Integrating our findings into a regional perspective, we identify a continuous Early Pleistocene uplift phase spanning a large segment of the Andean margin, from 16 degrees to 42 degrees S. This orogen-scale emergence implies a subtle but widespread change in subduction dynamics during the last similar to 2 Myr.

Abstract Uplifted Pleistocene marine terraces in the Illapel area along the forearc of central Chile record spatially and temporally variable uplift rates on glacial‐cycle timescales. However, the underlying mechanisms for this uplift variability and its potential relationship with the megathrust‐earthquake cycle remain poorly understood. The Illapel region was affected by the 2015 MW8.3 Illapel earthquake and provides an opportunity to assess the relationship between the megathrust seismic cycle and permanent coastal uplift. We combined mapping of late Pleistocene marine terraces along 300 km of coast with stratigraphic and sedimentological analyses, luminescence dating, morphometry, and numerical modeling to constrain the timing and rates of deformation. Our results reveal modest uplift rates of 0.1–0.2 m/ka during Marine Isotope stages (MIS) 9 and 5e that were superseded by rates between 0.5 and 0.9 m/ka during MIS 7, lasting for about 200 ka. The lack of a correlation between terrace‐uplift rates and GPS velocities at the decadal scale suggests that permanent forearc deformation is unrelated to the coseismic and interseismic phases of the Illapel earthquake cycle. We also discard the influence of upper‐plate normal faulting on patterns of surface deformation, as our dislocation modes suggest that it plays a secondary role. Instead, we propose that the short period of uplift acceleration was linked with changes in the margin boundary conditions caused by subduction of bathymetric anomalies from adjacent sea‐mount chains. These results highlight the complexity of mechanisms controlling forearc deformation and the hidden dynamics of deep processes in subduction systems.

Chile's west coast is frequently struck by megathrust earthquakes and tsunamis, as illustrated by the CE 2010 Maule ( M w 8.8) and CE 1960 Valdivia ( M w 9.5) events. Despite numerous palaeoseismic and palaeotsunami studies, uncertainties remain regarding the rupture extent and tsunamigenic potential of M w 8–9 earthquakes. This study examines the sedimentary record of Laguna Gemela West, a coastal lake at 5–6 m a.s.l. and of 17.5 m depth. It is separated from the Pacific by a 400 m long channel bordered by northward‐propagating dunes and controlled by Pleistocene sandstones forming a knickpoint in the channel profile. Multiple sedimentary proxies (e.g. grain‐size, X‐CT, XRF scanning) identified five distinct sand‐enriched layers, interpreted as tsunami deposits. Age‐depth modelling (based on 137Cs and 14C) allowed linking these deposits to the CE 2010, 1960, 1837, 1737 and 1575 megathrust earthquakes. While historical records confirm significant tsunamis in CE 2010, 1960, 1837 and 1575, no reports exist for a CE 1737 tsunami. However, a potential tsunami deposit and evidence for subsidence were found at the nearby Chaihuín site, albeit with large dating uncertainty (CE 1600–1820). The more precise age for a sand layer at Laguna Gemela West (CE 1672–1746) supports the occurrence of a local tsunami in CE 1737. Additionally, deposits linked to the CE 1837 and 2010 events suggest tsunamis can impact sites >100 km adjacent to megathrust ruptures. A second pulse in the uppermost sand layer may reflect the CE 2011 Japan tsunami, which reached a similar height (~1.6 m a.s.l.) in the nearest tide gauge as the CE 2010 tsunami. Unlike coastal plain sites, which often require coseismic subsidence for deposit preservation, coastal lakes can capture a more complete tsunami history. This study highlights their complementary role in palaeotsunami research, providing insights in local, regional and transoceanic tsunami events.

Overlying the subducting Nazca Plate, Chile’s coastline is notoriously prone to megathrust earthquakes and associated tsunamis, as illustrated by the 2010 Maule (Mw 8.8) and 1960 Valdivia (Mw 9.5) events. Despite numerous geophysical and paleoseismic studies, many questions remain about the timing, location and rupture extent of great tsunamigenic earthquakes. To study past tsunami inundation, coastal lakes may form complementary sedimentary archives to classical coastal plain studies as they have more accommodation space and a better preservation potential for tsunami deposits. Moreover, tsunami inundation may lead to prolonged changes in the lake system that are reflected in its sedimentary record. Here we present an overview of published and ongoing research on four coastal lake systems in Chile, i.e. Lake Gemelas West, Lake Huelde, Lake Cucao and Lake Huillinco. Due to their different basin and barrier morphologies, distance to the ocean and temporally-changing ocean connectivity, we expect significant differences in how tsunami inundation is recorded in their sediments. We used the 1960 tsunami deposit in these systems as a reference for which we constrain its sedimentological characteristics and spatial distribution within the lakes. Geochemistry of the pre- and post-1960 sediments is compared based on XRF scans, carbon isotopes and microfacies analysis. This comparison shows that lakes close to the Pacific (i.e. Lake Cucao, Huelde and Gemelas West) contain typical tsunami sands sometimes with mud-rip up clasts, whereas the inland Lake Huillinco exhibits a drastic change in inorganic geochemistry (e.g. a sudden increase in S) that persists until present. We propose that a large amount of salt water propagated in Lake Huillinco, leading to a permanent stratified water body, anoxic bottom water conditions and the preservation of varves. Similar long-lived impacts are also inferred for prehistoric tsunami events in Lake Huelde, where post-tsunami sediments often show varves during a few decades, whereas pre-tsunami sediments are typically homogenous. This study shows that besides tsunami sands, tsunami inundation can also produce long-lived changes in coastal lake systems that are recorded in their sedimentary archive and can be used to infer past tsunami occurrence.

Understanding vertical deformation associated with cycles of great megathrust earthquakes is crucial for assessing coastal hazards and advancing in our knowledge of tectonic processes in subduction zones. However, this requires long datasets that extend beyond the era of space geodesy. Here, we use paleoseismological evidence, including lithological and paleoecological data, from a former coastal lagoon in central Chile to reconstruct land-level changes during the 20th century, spanning two great (M >= 8) megathrust earthquakes in 1906 and 1985. Diatom and seed assemblages across an abrupt lithological change from mud to peat recorded a sudden relative sea level (RSL) fall in the early 20th century. This environmental shift correlates with the disappearance of the lagoon between 1904 and 1914 as documented in historical maps, revealing an emergence event most likely associated with similar to 0.7 m of coseismic uplift in 1906. For the following eight decades, diatoms suggest relatively stable RSL conditions, implying that the coast remained emerged. This is partially supported by the record of a nearby tide gauge showing relatively stable RSL between 1944 and the mid-1980s. Around the time of the 1985 earthquake, both diatoms and tide gauge records suggest the onset of a gradual RSL rise. The inferred long-term trend aligns with modern GPS measurements showing persistent coastal subsidence since 1997 until today. This multiproxy RSL history reveals a more complex vertical deformation pattern than previosuly assumed in the central Chile subduction zone, with subsidence starting eight decades after sustained post-1906 uplift. Our findings provide key insights into the vertical deformation cycles of great subduction zone earthquakes in central Chile and elsewhere.

This study investigates the Holocene evolution of the Laraquete-Carampangue strandplain on the tectonically active coast of south-central Chile using ground penetrating radar and light detection and ranging data. The Laraquete-Carampangue strandplain, on the tectonically active coast of south-central Chile, is a rare accretionary feature in a region dominated by rocky shorelines and limited sediment supply. The light detection and ranging data-derived digital elevation model reveals a complex geomorphology comprising 52 beach ridges, aeolian dunes, and fluvial paleochannels, while ground penetrating radar radargrams uncover marine and aeolian facies influenced by past seismic and climatic events. We interpret these units in the frame of past seismic and climatic events. Our geomorphological and stratigraphic findings suggest that the strandplain progradation was driven by relative sea-level changes associated with Holocene seismic cycles and climate change. We propose that the transition from drier to humid conditions in the late Holocene triggered the onset of dune formation at the end of the Little Ice Age. This integrated approach highlights the interplay of tectonic and climatic forcings in shaping coastal landforms, offering insights into their long-term response to environmental change.

TerraceM is an open-source software written in MATLAB for mapping and analyzing marine terraces. In this latest release, TerraceM-3 has undergone significant evolution, which leverages the capabilities of machine learning to introduce an automated marine terrace mapping feature. This new version includes a neural network that has been meticulously trained with over 1000 mapped marine terraces. This allows TerraceM-3 users to effortlessly map marine terraces and precisely determine their elevation through the automated mapping of their shoreline angles. In addition, TerraceM-3 incorporates two new functionalities: 1) Photon profile mapping, which includes mapping of satellite LiDAR profiles from the IceSat-2 mission, which broadens the applicability of TerraceM-3 beyond the availability of topographic data. 2) Indicative meaning calculator that accounts for the factors that can alter the initial sea-level position using global datasets (wave conditions and tidal ranges). This method facilitates the direct assessment of uncertainties in the reconstructions of the paleo-sea-level based on marine terraces. TerraceM-3 is a complete toolkit for researchers and students engaged in marine terrace analysis by offering a unique blend of numerical methods, statistical analyses techniques and additional enhanced functionalities to precisely map marine terraces and using them as markers of tectonic deformation.

TerraceM is an open-source software for mapping and analysing marine terraces. One of the primary challenges in accurately mapping marine terraces is the limited availability of digital elevation data with the resolution necessary to capture the subtle and ephemeral morphology of these geomorphic features. Recent advancements in remote sensing, such as NASA's ICESat-2 satellite mission, offer new opportunities to address this limitation. The ICESat-2 was designed to study Earth's polar ice, land canopy, and bare-earth topography using its Advanced Topographic Laser Altimeter System (ATLAS), a laser-based instrument similar to a LiDAR sensor, providing highly accurate surface elevation measurements in the form of geolocated photons along profiles. While the data are not continuous, the mission has completed thousands of orbits, densely covering most of the world's coastal areas with photon profiles, making it possible to achieve highly accurate mapping of marine terraces. The latest version of TerraceM introduces new scripts and graphical user interfaces (GUIs) to efficiently interact with ICESat-2 photon data. These features enable users to select, download, preprocess, and map marine terraces interactively. Preprocessing capabilities include filtering canopy signals and reconstructing nearshore bathymetry, allowing the analysis of both subaerial and submarine terraces. Additionally, the new version of TerraceM supports MATLAB and Python, broadening its accessibility to a wider range of users. TerraceM-3 delivers advanced modelling and mapping functionalities, empowering researchers and students involved in marine terrace studies. By leveraging ICESat-2 data, TerraceM significantly extends our ability to analyse past sea-level changes and understand the interplay between tectonics and climate processes in coastal environments.

The southward propagation of the southern Main Ethiopian Rift (sMER) and the northward propagation of the Kenya Rift have generated the Broadly Rifted Zone (BRZ), a ~40-km-wide region of extensional overlap between the Chew Bahir Basin-Gofa Province and the sMER. However, the tectonic interaction between these propagating rifts is not well-understood. We present new paleomagnetic and geochronologic data from Eo–Oligocene (45–35 Ma) and Miocene (18–11 Ma) volcanic and sedimentary rocks from the BRZ. Rock magnetic, alternating field and thermal demagnetization experiments indicate simple titanomagnetite mineralogies carrying a characteristic remanent magnetization from which straightforward magnetization directions were obtained. Site-mean paleomagnetic directions obtained from the analyzed samples reflect stable normal and reversed polarity directions. A comparison of the mean directions obtained for the Eo–Oligocene and Miocene rocks relative to the pole for stable South Africa at the corresponding ages reveals a significant counterclockwise (CCW) rotation of ~11.1° ± 6.4° and insignificant CCW rotation of ~3.2° ± 11.5°, respectively, reflecting a decrease in the extent of block rotations through time. Our results are consistent with the regional migration patterns of deformation during rifting. In the context of the regional tectonic evolution toward a narrow zone of extension, much of the deformation associated with block rotations probably occurred prior to the final stages of the emplacement of the Miocene volcanic flows. In light of the structural fabrics in the basement rocks exposed in the sMER, the observed CCW block rotations were likely accompanied and aided by the reactivation of NW-SE-striking basement heterogeneities, supporting the notion that inherited crustal-scale structures play a significant role during rifting across the BRZ.

Crustal reverse faults are recognized for their potential to generate devastating earthquakes, making them a focus of seismic hazard assessment. Along the Chilean Andes, the Western Andean Thrust System (WATS)—a structure marking the Central Valley-Principal Cordillera border—includes several probable late Quaternary faults. However, evidence for large Holocene earthquakes (M~7) has only been confirmed on two faults at ~32-33°S. This study focuses on the WATS at ~36°S, where a hectometer-scale escarpment dominates the border between the Central Valley and Principal Cordillera. LiDAR-derived topography, new geologic mapping of Pliocene to Quaternary units, and morphological analysis reveal that the mountain front and surrounding areas have undergone tectonic deformation since at least the Pliocene. Approximately 200 m west of the mountain front, we mapped a 0.7-to-8.7-m-high fault scarp in alluvial deposits dated at ~14 ka with Optically Stimulated Luminescence (OSL). Morphotectonic analysis of the scarp and faults mapped in two trenches demonstrates that the scarp formed during moderate to large Holocene earthquakes along the newly identified Mesamávida fault. A local seismic network also detected crustal seismicity likely attributable to the fault. At least one branch fault of the WATS at 36°S—the Mesamávida fault—has the potential to generate earthquakes with magnitudes up to ~7.1. The seismic potential of the Mesamávida fault should be incorporated into hazard analyses for central-southern Chile. Study of similar faults within the WATS to the north and south will enhance understanding of this thrust system's seismic hazard and its role in Quaternary tectonics of the Andes.

South-Central Chile is a geodynamically very active area that experiences great subduction megathrust earthquakes, mass-wasting processes and frequent volcanic eruptions. These processes can induce sudden landscape changes that leave long-lasting geomorphological and sedimentary traces. They can also lead to significant lake level rise, but evidence for this is exclusively found under water and hardly investigated. Lago Llanquihue (41.156°S; 72.816°W) is a large and deep (40 x 40 km; 317 m deep) piedmont lake at the western foot of the Andes, and forms an important touristic hotspot. Its current outflow is at the western edge and its small catchment is dominated by two active volcanoes: Osorno and Calbuco. Based on previous geomorphological studies in the 1960-70s, it was hypothesized that the lake level of Lago Llanquihue was much lower during most of the Holocene and rose to its present level only in the Late Holocene. According to the hypothesis, lahars and/or lava flows in the late Holocene dammed the outflow in the eastern part of the lake system leading to lake level rise and subsequent drainage towards the west through the frontal moraine belts. In this study, we aim to test and constrain this hypothesis by investigating the submerged geomorphological features and sedimentation patterns in Lago Llanquihue. We complement this data by a sedimentary study of Laguna La Poza, a small lake (1.7 x 0.2 km; 6 m deep) in a fluvial valley that is believed to have been inundated by the Late-Holocene lake level rise. Seismic-stratigraphic analysis of Lago Llanquihue reveals submerged lake level terraces (ca. 35-55 m water depth) of which individual levels can be traced in different parts of the lake. These terraces are constituted of erosional unconformities and delta topset geometries, and are covered only by a thin (0.5-3 m) drape of lacustrine sediments. Short sediment cores show different lithologies below these unconformities: fine-grained grey laminated sediments with dropstones, or coarse sand with shell fragments. These are interpreted as glaciolacustrine sediments from Late Glacial times and as sandy beach environments, respectively. Additionally, Laguna La Poza shows a significant change in sedimentation at about 1 m depth, where a laterally-variable fining-upwards medium sand to gravel unit with pronounced cross-stratification is covered by horizontally-stratified fine-grained organic-rich lake sediments. We interpret this sequence as evidence for a sudden inundation of a fluvial valley by a rising Lago Llanquihue. Given the rather thin drape of lake sediments over the unconformity (Llanquihue) and fluvial sediments (La Poza), a Late Holocene timing of lake level rise is plausible. Current investigations aim at correlating both lacustrine sedimentary records by geochemical analysis of tephra marker layers and use 14C dating to constrain the timing of the sudden lake level rise.

Multi-millennial records of great megathrust earthquakes have highlighted differences in periodicity and recurrence behavior. Understanding tectonic processes responsible for these differences is relevant for fault mechanics and hazard models. Here, we present a paleoseismic record inferred from raised beach ridges in the 2010 Maule earthquake (Mw 8.8) segment in south-central Chile that includes 24 interseismic intervals over 4.5 kyr suggesting a weakly-periodic recurrence behavior. In turn, great earthquakes in the adjacent 1960 Valdivia earthquake (Mw 9.5) segment occurred with periodic recurrence over the same time span. Both segments have similar trench sediments thicknesses as well as rheological and geometrical boundary conditions, but Maule has a wider frontal accretionary wedge and several splay faults rooted in the seismogenic zone whereas Valdivia lacks splay faults and trench sediments are mostly subducted and underplated. These differences may have an impact on upper-plate compliance and megathrust friction, affecting earthquake size and recurrence periodicity. A paleoseismic record inferred from raised beach ridges along the Maule earthquake segment of the south-central Chilean margin displays weakly-periodic recurrence behaviour in comparison to strong periodicity over the nearby Valdivia segment

Damming rivers by landslides and ensuing outburst flooding is a common and potentially hazardous phenomenon worldwide, especially in tectonically active regions. Remarkable examples are the damming of the upper course of the San Pedro River (SPR) in south Chile during the 1960 Chile earthquake (M9.5) and its predecessor in 1575. Outburst floods following both events had tragic consequences for downstream communities. Here, we study both events from multiple sources of information, including previously published and newly found historical records, satellite imagery, LiDAR topography, and sedimentological and geomorphological field observations. We present the first detailed geomorphic map of the region. Morphological similarities between ancient deposits at the SPR and those associated with the 1960 earthquake suggest that the SPR has been dammed repeatedly in the past. The steep incision of the SPR and the sediments of glacio-lacustrine origin in the surrounding slopes facilitate the initiation of large landslides. The knowledge gained from studying these past events provides important implications for future risk assessments. We propose that besides large earthquakes, smaller and more frequent earthquakes as well as changes in land use, can also result in river-damming events.

Supporting information accompanying a paper entitled "Magma-assisted Continental Rifting: The Broadly Rifted Zone in SW Ethiopia, East Africa" submitted to AGU publications, Tectonics. The dataset contains apatite and zircon (U-Th-Sm)/He data from the southern Main Ethiopian Rift, Gofa Province and Chew Bahir Basin, as well as additional QTQt thermal models that are discussed in the paper. Table 1 and 2 contain apatite (AHe) (U-Th-Sm)/He (Table 1) and zircon (ZHe) (U-Th-Sm)/He (Table 2) single grain ages. Sampling locations are indicated in figure 2a in the main text. Data table 1 and 2 are similar with Table 1 and 2 in the main text. Table 3: Show Onset of cooling and cooling rate estimated for each model. Supplementary information S1A and S1B show model input data and modeling strategy for QTQt (S1A1) and HeFTy (S1A2). Supplementary information S2A1–S2A4: Show AHe single grain ages plot against effective uranium concentration (eU) and grain size (ESR) colored with grain geometry (1, 2 or 0 terminations). Single grain ages excluded for QTQt modeling are denoted as asterisk. S2A5: AHe single grain ages plot against effective uranium concentration (eU) and grain size (ESR) colored with grain geometry (1, 2 or 0 terminations). Supplementary information S3A1 shows all QTQt thermal modeling results for individual and elevation profile samples. The expected thermal history represents the weighted mean of all the models sampled (solid lines). For elevation profile samples, thermal history for the topmost and lowermost samples plotted in blue and red, respectively. For all models, the 95% confidence interval drawn as stippled lines. For elevation profile samples, thermal histories for samples in between the top and lower are drawn in gray. Supplementary information S3A2: Shows individual HeFTy inverse and forward modeling results. Excluded single grain ages are denoted as transparent. Accepted thermal histories are indicated as green and the ''good'' fits are light purple. The orange boxes are time-temperature constraints. Note: M-1A and M-1B are model results for sample M-1. We rerun the same model to increase the number of "good" fit time temperature history paths for model M-1A..

Earthquakes and tsunamis are natural phenomena that have strongly affected communities located along the Chilean active plate margin. Large-magnitude megathrust earthquakes produced at the plate interface of the subduction zone and their associated tsunamis have repeatedly impacted the Chilean coast, leaving a sedimentary record at particular sites from historic and prehistoric times. Here we assess paleoseismic sites related to late Holocene (< 1.5 ka) earthquakes and tsunamis that occurred along the Pacific coastline of south-central Chile (38°-42°S), which record critical information for the study of megathrust earthquakes. We focus on sites along the Valdivia segment that were affected by the great earthquake and tsunami of 1960 (Mw = 9.5; the largest recorded by modern seismology), which host geologic evidence of coseismic land-level changes found in tidal marshes and wetlands. We present an inventory of seven paleoseismic geosites composed mainly of different layers of buried soils and sand deposits, and a quantitative assessment of their scientific value, their potential touristic and educational value, and their degradation risk. These sites are considered part of the paleoseismic heritage of Chile and are relevant globally. Our inventory contributes to the establishment of management strategies for geoconservation of the coastal area of south-central Chile, and the mitigation of the effects of seismological hazards through the promotion of educational, touristic and outreach activities.