The Huangzuei complex is a volcanic complex within the 25 km-wide Tatun Volcanic Group (TVG), which is situated on the northern tip of Taiwan and poses significant potential hazards to the Taipei metropolitan area. The Huangzuei complex has well-preserved landforms with three sets of lava flows that radiate northwestward, northeastward and southeastward up to several kilometers from Mt. Huangzuei, the 250-m-high cratered summit of the Huangzuei complex.High-resolution topography from a LiDAR-based bare-earth DEM enables detailed demarcation and characterization of individual flows, including volume, thickness, and profiles. Results of our geomorphological mapping and 40Ar/39Ar dating of volcanic matrix reveal that eruption of the Huangzuei complex began at 139 ka, was most vigorous from ~129 ka to 133 ka and resumed at ~116 ka. The south-eastern branch of lavas partially overlap ~264-298 ka lavas that may have erupted from Dajianhou, another neighboring volcanic complex. It is likely that the Huangzuei volcanism ended in the formation of domes and a summit crater at 85 ka or later.Disequilibrium textures, including oscillatory zoning, reverse zoning, partial resorption, and development of reaction rims, are common in samples from the Huangzuei complex. These textures, together with the wide ranges of mineral compositions (Mg# of pyroxenes and An content of plagioclase), indicate that the magma that formed the Huangzuei complex underwent intense magma hybridism, likely involving periodic replenishment by more primitive magmas during crystallization differentiation. We propose the latter as the cause of the voluminous lava emplacement from ~129 to ~133 ka.

Emotions coordinate our behavior and physiological states during survival-salient events and pleasurable interactions. Even though we are often consciously aware of our current emotional state, such as anger or happiness, the mechanisms giving ...Emotions are often felt in the body, and somatosensory feedback has been proposed to trigger conscious emotional experiences. Here we reveal maps of bodily sensations associated with different emotions using a unique topographical self-report method. In ...

The Sumatran Fault Zone (SFZ) of the Indonesian island of Sumatra, which is broken up into 19 fault segments, accommodates much of the trench-parallel component of the oblique convergence between the Indo-Australian and Sunda plates. To understand the potential hazard of SFZ earthquakes to the local population, we investigate slip rates and locking depths of three SFZ segments in southern Sumatra using previously unpublished data from our Sumatran Fault Monitoring (SuMo) campaign Global Positioning System (GPS) network. We model the GPS data using a 2-D interseismic dislocation model optimized using a Bayesian approach. For the Musi segment of the SFZ, we find that slip rates ranging from 10 to 22 mm yr-1 and locking depths from 1 to 20 km fit the data similarly well, suggesting a lack of resolution for the SuMo network in this segment. For the Manna and Kumering segments where the resolution is better, the estimated slip rates are 18 [12-22, 95 per cent confidence intervals] mm yr-1 and 12 [9-15] mm yr-1, respectively, while the estimated locking depths are 29 [15-47] km and 5 [3-16] km, respectively. The deep locking depth estimated for the Manna segment can be explained by the large station gap in this segment. Considering the uncertainty, all the estimated slip rates from our study remains aligned with the SFZ's average slip rate of similar to 15 mm yr-1, which was previously derived using updated geological slip rates and geodetic block modelling of the entire SFZ. Our results support the idea that the forearc sliver west of the SFZ behaves as a rigid microplate.

Sediments in southern Laos and eastern Thailand confirm that the Australasian tektite strewn field came from an extraterrestrial impact crater on the Bolaven Plateau of southern Laos. The principal evidence is the Bolaven diamicton, a pebbly to bouldery breccia that is thickest and coarsest on the plateau. Tektites, the melted target material strewn widely by the forces of the impact 789.0 ± 1.8 ka ago, lie either within the uppermost part of the diamicton or atop it. On the flanks of the plateau, the basal diamicton often contains clasts from preimpact lavas and gravels and sometimes mantles broken Mesozoic bedrock. Locally, its upper portions contain unweathered boulders of basalt or sandstone. Its sharp upper contact with a thick sandy silt implies that the two beds formed in rapid succession. These characteristics of the Bolaven diamicton show that it resulted primarily from the excavation, comminution, and launch of sandstone and weathered basaltic lavas from a crater on the Bolaven Plateau, and entrained other materials while in transit.

Southeast Asia is home to a large number of active and well-studied volcanoes, the majority of which are located in Indonesia and the Philippines. Northern Southeast Asia (Myanmar, Cambodia, Laos, Thailand and Vietnam) also hosts volcanoes that for several reasons (post-World War II conflicts, poor accessibility due to dense vegetation, no known historical activity) have been poorly studied. Systematic assessments of the threat these volcanoes pose to resident populations do not exist, despite evidence of numerous eruptions through the late Pleistocene and likely even during the Holocene. A recent study inferred the location of the Australasian meteorite impact to be beneath the Bolaven Volcanic Field in southern Laos; this study provided a wealth of data for the field: in particular, mapping of vents and flows, and their relative or absolute ages. The Bolaven Volcanic Field (16 Ma—< 40 ka) has a surface area of about 5000 km2, contains nearly 100 scoria cones and more than 100 individual lava flows. Some lava flow systems are as long as 50 km, with thickness ranging from a few meters at the flow edges, up to > 50 m in some locations. Building upon this foundation, we used the Bolaven Volcanic Field as a case study for assessing the potential exposure of populations and infrastructure to lava flows during future effusive eruptions. Our study uses remote sensing to map past flows and vents (i.e. scoria cones), lava-flow simulations from new simulated vents, and open-access exposure data, to assess hazards and exposure. Our results show that future vents are most likely to occur in a N-S band atop the Bolaven plateau, with some flows channelling into canyons and spilling down the plateau flanks onto lower plains that support more populated areas such as the provincial centre, Pakse. Our exposure assessment suggests that around 300,000 people could experience socio-economic impacts from future lava flow inundations. The largest impacts would be on two of the main economic sectors in the region, agriculture and hydropower. The potential also exists for life-threatening explosions from interactions between magma and surface waters, which are abundant in the region. We estimate an average recurrence interval of approximately 10,400 years, based on information from lava flows and scoria cones.

This study presents a distinctive type of Muslim gravestone found on the northern coast of Sumatra, Indonesia, that dates to the 15th century. These grave markers, locally known as plang-pleng, provide evidence for the formation and disappearance of an early form of vernacular Muslim material culture in Southeast Asia. We documented over 200 of these gravestones during a large-scale archaeological landscape survey. In this article, we present a typology of these gravestones based upon shape, morphology and ornamentation. We then discuss their geographical distribution and periodisation based on examples with dated Arabic inscriptions. Our results show that these gravestones were initially a cultural product of the historic trading settlement of Lamri dating from the early 15th century. By the middle of the 15th century, variations of these stones started to appear widely near the Aceh river. The plang-pleng tradition was displaced in the early 16th century by the batu Aceh gravestones associated with the Aceh sultanate, which became a standardised part of Muslim material culture in the region for the next two centuries.

We review published literature and historical texts to propose that three periods of official Chinese maritime bans impacted the composition and circulation of trade ceramics along Asian trade routes: Ming Ban 1 (1371 – 1509), Ming Ban 2 (1521 – 1529), and Qing Ban (1654 – 1684). We use ceramics collected during a landscape archaeology survey along 40km of coast in Aceh, Indonesia to show how the three ban periods manifest in the ceramic record of settlements along an important stretch of the maritime silkroad. All three ban periods overlap with reductions in the quantity of Chinese ceramics. Within several decades of the start of Ming Ban 1, people in Aceh began importing ceramics from production centers in Burma and Thailand as a substitute for Chinese ceramics. Following Ming Ban 2, there is an increase in imports from Chinese production centers, albeit from new kilns sites. While brief, the Qing ban resulted in an almost immediate influx of ceramics from Japan and Vietnam, which maintained some market share until the mid-17th century, after which Chinese ceramics dominate the record until the end of the Qing dynasty. Our data show both the importance of Chinese ceramics within regional trade networks and how those networks and local patterns of consumption adapted to disruptions of supply.

Surface projection of the slip model for the 1966-1981 slow-slip event (SSE) in the Sumatran subduction zone

Sudden breaching of a saddle dam on July 23, 2018, on the perimeter of the Xe Nammoy hydroelectric-power reservoir, recently constructed in the Mekong basin, southern Laos, caused catastrophic flooding that resulted in fatalities and displaced thousands of individuals. This study aims to (1) assess the cause of the dam breach, and (2) understand the hydrologic and geomorphic impact of the flood. Our analysis shows that the collapse of the dam occurred as the reservoir was nearly full, and the water level was rising against the inner slope of the earthen dam. As the water discharged through the breach, we calculate that the reservoir fell similar to 22 m and lost similar to 350 million m(3). more than a third of the total stored volume on July 23. Inspection of publicly available photographs of the failed dam confirms our interpretation that the failure was structural, involving both piping and rotational slumping, and not due to overtopping of the dam. Failure to properly process the local materials before construction of the earth-core of the dam is the likely cause of failure. Our analysis of satellite imagery, bolstered by field observations, reveals that the flooding inundated an area of similar to 46 km(2) of villages and rural land in the Vang Ngao River, a tributary of the Mekong River basin. By using 1D and 2D hydrological modeling, we calculate a peak flood discharge of similar to 8500 m(3)/s, about half the mean discharge of the Mississippi River. The dam failure and concomitant losses are consistent with common inadequacies in this region in assessing potential hazards, challenges of geomorphological-geotechnical engineering when using tropical materials for construction, and emergency planning and warning. Thus, this analysis has important implications for the safer design and construction of the myriad of other dams that are either operating or planned within the multi-national Mekong River basin. (C) 2020 The Authors. Published by Elsevier B.V.

The crater and proximal effects of the largest known young meteorite impact on Earth have eluded discovery for nearly a century. We present 4 lines of evidence that the 0.79-Ma impact crater of the Australasian tektites lies buried beneath lavas of a long-lived, 910-km3volcanic field in Southern Laos: 1) Tektite geochemistry implies the presence of young, weathered basalts at the site at the time of the impact. 2) Geologic mapping and40Ar-39Ar dates confirm that both pre- and postimpact basaltic lavas exist at the proposed impact site and that postimpact basalts wholly cover it. 3) A gravity anomaly there may also reflect the presence of a buried ∼17 × 13-km crater. 4) The nature of an outcrop of thick, crudely layered, bouldery sandstone and mudstone breccia 10–20 km from the center of the impact and fractured quartz grains within its boulder clasts support its being part of the proximal ejecta blanket.

Nous présentons les preuves archéologiques d’un établissement commercial datant du XIIIe au milieu du XVIe siècle EC sur un promontoire élevé du village de Lamreh, à environ 30 km à l’est de Banda Aceh, sur la côte nord de Sumatra, en Indonésie. Nous l’identifions au site historique de Lamri, décrit par les sources textuelles comme un noeud important de la « route de la soie » maritime entre le IXe et le XVIe siècle EC. Notre prospection a révélé de grandes concentrations de céramiques sur le promontoire, qui datent du début du XIIIe siècle jusqu’au milieu du XVIe siècle, certaines de qualité impériale. Plusieurs des stèles funéraires musulmanes de ce site sont d’un type particulier et datent de la quasi-totalité du XVe siècle. Les données géologiques suggèrent que les parties basses de Lamri ont été détruites par un fort tsunami à la fin du XIVe siècle. Cependant, nos données montrent que l’activité sur le promontoire s’est poursuivie jusqu’à ce que le site soit abandonné au milieu du XVIe siècle. L’absence de culture matérielle datant du IXe au XIIIe siècle suggère que les références textuelles antérieures à Lamri se référaient plus généralement à une grande partie de la côte nord de Sumatra, le village de Lamreh ne devenant le centre géographique du Lamri historique qu’après le tournant du XIIIe siècle.

Due to an unfortunate oversight we did not publish the hypothetical slip model

Propagation of fault rupture to the seafloor is a likely cause of enhanced tsunami generation during megathrust earthquakes. New, high-resolution seismic reflection profiles and swath bathymetry collected across the northern limit of the M-w 7.8, 25 October 2010 Mentawai tsunami earthquake rupture reveal significant and systematic lateral variations in both the stratigraphic level of the frontal Sunda megathrust and the vergence of its frontal ramp faults. Where ramp faults are uniformly seaward vergent, the decollement resides on top of a strong reflector marking the inferred top of pelagic sediments. Where ramp faults are bivergent (both landward and seaward), the decollement is localized within the subducting clastic sequence, above a xseismically transparent unit inferred to be distal fan muds. Where ramp faults are uniformly landward vergent, the decollement is directly on top of the oceanic crust of the subducting Investigator Fracture Zone. Enhanced surface uplift and tsunamigenesis during the 2010 tsunamigenic earthquake appear to have coincided with propagation of rupture into frontal areas with well-developed structural bivergence. Frontal bivergence is a geological signal of low basal traction during accrual of slip, and offshore of Sumatra this structural style may mark areas of enhanced tsunami hazard posed by small-magnitude, shallow megathrust ruptures that propagate into the incoming terrigenous sequence at near-trench levels. Plain Language Summary Very large magnitude subduction earthquakes commonly produce huge tsunamis that devastate shorelines great distances away from the source. These tsunamis are generally preceded by strong ground shaking that warns coastal residents near the rupture area to evacuate. Over the last several decades, the subduction zone south of Sumatra and Java has produced three deadly tsunamis that were caused by much smaller-magnitude earthquakes. The high casualty count of these events, called tsunamigenic earthquakes, is largely due to the lack of warning from major ground shaking before arrival of the tsunami waves. The cause of these earthquakes remains poorly understood and few studies have directly examined the fault systems that produce the excessively large waves. We used seismic reflection and bathymetry data to study an area of the Sumatran subduction zone that produced a tsunamigenic earthquake in 2010 and killed more than 500 people. We focused on understanding the different kinds of rock the shallowest megathrust fault cuts through, which might have different frictional properties. By comparing the stratigraphic position of the fault with the geological structure of the overlying wedge, we show that excessive slip occurred in a specific geological context that indicates low friction on the fault surface. This is a significant step in better understanding how tsunamigenic earthquakes happen in this region.

Significance We demonstrate that a tsunami in the late 14th century CE destroyed coastal sites along a critical part of the maritime Silk Road and set in motion profound changes in the political economy of Southeast Asia. Our results provide a precise chronology of settlement and trade along a historically strategic section of the Sumatran coast and are robust physical evidence for the rise of the Aceh Sultanate. Tragically, coastal areas impacted by the late 14th century tsunami were devastated by the 2004 Indian Ocean tsunami. This makes our findings relevant to debates about hazard mitigation and risk reduction. This example shows that archaeological, historical, and geological data are relevant in discussions about the long-term sustainability of communities exposed to geological hazards.

The Wharton Basin in the Indian Ocean is one of the most extensively deforming ocean basins, as confirmed by the occurrence of several very large earthquakes starting from January 12, 2012 with Mw 7.2 followed by the great earthquakes of April 11, 2012 with Mw 8.6 and Mw 8.2. Although the Mw 7.2 and Mw 8.2 earthquakes seem to have ruptured the re-activated N-S striking fracture zones, the largest event (Mw 8.6) required the rupturing of several faults, oblique to each other, in a very complex manner. In order to understand the nature of deformation in these earthquakes rupture zones, we recently acquired 90 000 km(2) of bathymetry, 11 400 km of sub-bottom profiling, gravity and magnetic data covering the rupture areas of the 2012 earthquakes east of the Ninety-East Ridge, in the northwestern Wharton Basin. These new data reveal six N8 degrees E striking re-activated fracture zones (F5b, F6a, f6b, F7a, F7b and F8), where the fracture zone F6a can be followed for over 400 km and seems to be most active. The epicenters of the Mw 8.6 and Mw 8.2 earthquakes lie on the fracture zones F6a and F7b, respectively. The newly observed fracture F5b in the east is short, and has an extensional basin at its southern tip. The fracture zone F8 defines the eastern boundary of the Ninety-East Ridge. The presence of en echelon faults and pull-apart basins indicate left-lateral motion along these fracture zones. In between these fracture zones, we observe pervasive 290 degrees striking right-lateral shear zones at 4-8 km intervals; one of which has cut through a seamount that might have ruptured during the Mw 8.6 earthquake. We also observe another N20 degrees E striking left-lateral shear zones in the vicinity of F7b and F8, which is coincident with the strike of one of the nodal planes of the Mw 8.6 focal mechanism. These N20 degrees E striking shear zones are interpreted as R Riedel shears and the N290 degrees E striking shear zones as R' Riedel shears. These shear zones are formed by a series of N335 degrees E striking en echelon normal faults. Our data also show the presence of N65 degrees E striking thrust faults east of the Ninety-East Ridge, orthogonal to the regional principal direction of compression. Furthermore, extensive bending-related faulting is also observed close to the Sumatra trench with normal faults also striking at N335 degrees E, similar to the normal faults that form the shear zones. Normal faults with a similar orientation are also present at the southern tip of F5b. We explain all these observations with a single coherent model of deformation in the Wharton Basin, where a dominant part of the regional NW-SE compressional stress is accommodated along the N8 degrees E re-activated fracture zones, and the rest is distributed along shear zones, thrust and normal faults between these fracture zones. The thrust and normal faults are orthogonal to each other and define the direction of principal compressive and extensive stresses in the region whereas the two shear zone systems form a conjugate pair. (C) 2018 The Authors. Published by Elsevier B.V.