Historical intensity VIII earthquakes along the Rhone valley (Valais, Switzerland): primary and secondary effects

In recent years the upper Rhone Valley has been one of the most intensively investigated regions by the Swiss Seismological Service. The high seismicity in the region encourages research in the seismological field and one main focus has been historical seismology. This report presents the state of the art of our historical investigations by giving an overview of the effects of four damaging earthquakes with intensity larger than VII, for which a fairly large number of documents could be found and analyzed. The overview includes the events of 1584 (Aigle, epicentral intensity VIII), 1755 (Brig, epicentral intensity VIII), 1855 (Visp, epicentral intensity VIII), and 1946 (Sierre, epicentral intensity VIII for the main shock and intensity VII for the largest aftershock). The paper focuses mainly on primary and secondary effects in the epicentral region, providing the key data and a general characterization of the event. Generally, primary effects such as the reaction of the population and impact on buildings took more focus in the past. Thus building damage is more frequently described in historic documents. However, we also found a number of sources describing secondary effects such as landslides, snow avalanches, and liquefaction. Since the sources may be useful, we include citations of these documents. The 1584 Aigle event, for example, produced exceptional movements in Lake Geneva, which can be explained by an expanded sub aquatic slide with resultant tsunami and seiche. The strongest of the aftershocks of the 1584 event triggered a destructive landslide covering the villages Corbeyrier and Yvorne, VD. All macroseismic data on the discussed events are accessible through the webpage of the Swiss Seismological Service (http://www.seismo.ethz.ch).     

Applying GNSS and DTM Technologies to Monitor the Ice Balance of the Horcones Inferior Glacier, Aconcagua Region, Argentina

This work provides results and analysis of the behavior in a reconstituted debris covered glacier, Horcones Inferior (HIG). This glacier is located at 32° 41′ S and 69° 57′ W in the Aconcagua region, Mendoza, Argentina. The HIG has experienced surges events in 1984 and 2003. GNSS techniques and Digital Terrain Models (DTMs) derived from ASTER optical imagery, were used to detect movements and altimetric changes of the HIG in the 2001–2012 period. Based on a GNSS semi - continuous station, N and E mean velocities of 0.9 cm/d and 1.1 cm/d and in U direction were 1.1 cm/d and 1.5 cm/d were obtained respectively in 2009–2010 period. Additionally, GNSS profiles showed a velocity range between 0.5 cm/d and 2.8 cm/d. Finally, through a DTM comparison the altimetric change before and after the last surge in 2003 was obtained. The applied techniques allowed accurate and reliable change detection of the HIG.     

Microseismicity, tectonics and seismic potential in southern Caribbean and northern Venezuela

Approximately one thousand microearthquakes with body-wave magnitude mb have been located in northern Venezuela and the southern Caribbean region (9–12° N; 64–70° W) since the installation in 1980 of the Venezuelan Seismological Array, together with forty events of mb 4, one of them with surface-wave magnitude Ms 6. Focal depths are in the range of 0 to <15 km. This geologically complex region is part of the boundary between the Caribbean and the South American Plates. Epicentral locations indicate that this E–W oriented portion of the boundary is formed by two 400 km long subparallel fault zones: San Sebastián fault zone (SSF), 20 km north of Caracas along the coast; and La Victoria fault zone (LVF), 25 km south of the city. They are clearly delineated by the microseismicity. New composite focal mechanism solutions (CFMS) along these faults show right-lateral strike-slip (RLSS) motion on nearly E–W oriented fault planes. NW-striking subsidiary active faults occur in the region and intercept the two main E–W fault zones. These interceptions show high levels of microearthquake activity and seismic moment release when compared to other portions of both, the main and subsidiary faults. New CFMS at those fault crossing sites show NW-striking RLSS motion and normal faulting, in an en-echelon-like structural behavior. Geological data and quantitative comparisons with other transcurrent plate boundaries in the world suggest that the rate of plate motion in this area is on the order of 20 mm/y. Several moderate and large shocks have occurred along the SSF and LVF since 1640, including an Ms 7.6 event in 1900 on SSF. Although the region may be relatively far from a repeat of this earthquake, seismicity data indicate that strong shocks could take place along segments of the seismically active faults identified in this study.     

Late Miocene calc-alkalic volcanism in northwestern Mexico: an expression of rift or subduction-related magmatism?

Magmatism in NW Mexico records a Late Miocene transformation from convergence to extension in the Gulf of California rift system. Miocene calc-alkalic rocks in the Baja California peninsula are related to the final subduction of the Farallon plate system, but the heterogeneous nature of volcanism younger than 12.5 Ma has led to conflicting tectonic interpretations. Neogene volcanic rocks in the Sierra Santa Ursula, Sonora, were emplaced in three magma pulses, according to mapping, K–Ar geochronology, and geochemistry. From 23.5 to 15 and 14 to 11.4 Ma, calc-alkalic rocks show an arc-like signature. The 12–11 Ma calc-alkalic dacites, however, are characterized by higher K, Rb, ⁸⁷Sr/⁸⁶Sr, and light REE abundances than are the older rocks. The timing, petrography, and geochemistry of the 12–11 Ma rocks are interpreted to reflect postsubduction magmatism. A change in magma chemistry from predominantly calc-alkalic to tholeiitic rocks at 10.3 Ma corresponds to orthogonal extension during early Gulf of California evolution. Sr, Nd, and Pb radiogenic isotope signatures show minor changes over time. The volcanic record for 20–12.5 Ma at Sierra Santa Ursula and adjacent areas is consistent with the reconstructed history of the Guadalupe microplate. The interval of magmatism produced from 12 to 11 Ma appears to reflect changes in plate geometry during the transition from subduction to rifting.     

Variations in some physico-chemical parameters in a hypersaline coastal lagoon of Baja California,Mexico

San Jose lagoon is a hypersaline body of water located in Mexico in the Baja California Peninsula. The lagoon belongs to a system that lies between the fault ridge known as San Jose Creek. Because of its marine origin, it can be considered as thalassohaline, but its isolation from the ocean has brought about changes in its salt composition. It has an area of 13,500 m², a mean depth of 80 cm and a total volume of 10,000 m³. It does not desiccate and can be considered as a permanent lagoon. Seasonal variations are small. TheArtemia population in San Jose produces cysts all year. To determine the physico-chemical conditions inducing permanent production of cysts, temperature, salinity, dissolved oxygen, and pH of the lagoon were monitored, as well as relative humidity and wind conditions in the region in different seasons of the year. From spring to summer, differences of 1 mg L^–1 of O₂, 1°C in water temperature, and 8 g L^–1 in salinity were observed, and from summer to winter differences of 3.3 mg L^–1, 6.5°C, and 14 g L^–1, respectively. Despite small seasonal variations, the lagoon exhibits strong spatial and daily changes that are important for cyst production.     

A review of the tectonic evolution of the Sunsás belt,SW Amazonian Craton

The Sunsás–Aguapeí province (1.20–0.95 Ga), SW Amazonian Craton, is a key area to study the heterogeneous effects of collisional events with Laurentia, which shows evidence of the Grenvillian and Sunsás orogens. The Sunsás orogen, characterized by an allochthonous collisional-type belt (1.11–1.00 Ga), is the youngest and southwesternmost of the events recorded along the cratonic fringe. Its evolution occurred after a period of long quiescence and erosion of the already cratonized provinces (>1.30 Ga), that led to sedimentation of the Sunsás and Vibosi groups in a passive margin setting. The passive margin stage was roughly contemporary with intraplate tectonics that produced the Nova Brasilândia proto-oceanic basin (<1.21 Ga), the reactivation of the Ji-Paraná shear zone network (1.18–1.12 Ga) and a system of aborted rifts that evolved to the Huanchaca–Aguapeí basin (1.17–1.15 Ga). The Sunsás belt is comprised by the metamorphosed Sunsás and Vibosi sequences, the Rincón del Tigre mafic–ultramafic sill and granitic intrusive suites. The latter rocks yield ε_Nd(t) signatures (?0.5 to ?4.5) and geochemistry (S, I, A-types) suggesting their origin associated with a continental arc setting. The Sunsás belt evolution is marked by “tectonic fronts” with sinistral offsets that was active from c. 1.08 to 1.05 Ga, along the southern edge of the Paraguá microcontinent where K/Ar ages (1.27–1.34 Ga) and the Huanchaca–Aguapeí flat-lying cover attest to the earliest tectonic stability at the time of the orogen. The Sunsás dynamics is coeval with inboard crustal shortening, transpression and magmatism in the Nova Brasilândia belt (1.13–1.00 Ga). Conversely, the Aguapeí aulacogen (0.96–0.91 Ga) and nearby shear zones (0.93–0.91 Ga) are the late tectonic offshoots over the cratonic margin. The post-tectonic to anorogenic stages took place after ca. 1.00 Ga, evidenced by the occurrences of intra-plate A-type granites, pegmatites, mafic dikes and sills, as well as of graben basins. Integrated interpretation of the available data related to the Sunsás orogen supports the idea that the main nucleus of Rodinia incorporated the terrains forming the SW corner of Amazonia and most of the Grenvillian margin, as a result of two independent collisional events, as indicated in the Amazon region by the Ji-Paraná shear zone event and the Sunsás belt, respectively.     

A note on Einstein-Maxwell solutions and vacuum to electrovac solutions transforms

We discuss a direct construction of solitonic solutions in the Einstein-Maxwell system and analyze the connection of these with vacuum to electrovac transforms of the usual Belinskii-Zakharov vacuum solutions in the static and Einstein-Rosen waves cases.It should be noted that the construction of Belinskii is the same as the one that appears in the Kaluza-Klein ansatz, although in his case there is no direct interpretation to the scalarg ₅₅ fieldSupported by a CONICET fellowship.     

National climate change mitigation legislation,strategy and targets: a global update

Global climate change governance has changed substantially in the last decade, with a shift in focus from negotiating globally agreed greenhouse gas (GHG) reduction targets to nationally determined contributions, as enshrined in the 2015 Paris Agreement. This paper analyses trends in adoption of national climate legislation and strategies, GHG targets, and renewable and energy efficiency targets in almost all UNFCCC Parties, focusing on the period from 2007 to 2017. The uniqueness and added value of this paper reside in its broad sweep of countries, the more than decade-long coverage and the use of objective metrics rather than normative judgements. Key results show that national climate legislation and strategies witnessed a strong increase in the first half of the assessed decade, likely due to the political lead up to the Copenhagen Climate Conference in 2009, but have somewhat stagnated in recent years, currently covering 70% of global GHG emissions (almost 50% of countries). In comparison, the coverage of GHG targets increased considerably in the run up to adoption of the Paris Agreement and 89% of global GHG emissions are currently covered by such targets. Renewable energy targets saw a steady spread, with 79% of the global GHG emissions covered in 2017 compared to 45% in 2007, with a steep increase in developing countries.

Key policy insights

• The number of countries that have national legislation and strategies in place increased strongly up to 2012, but the increase has levelled off in recent years, now covering 70% of global emissions by 2017 (48% of countries and 76% of global population).

• Economy-wide GHG reduction targets witnessed a strong increase in the build up to 2015 and are adopted by countries covering 89% of global GHG emissions (76% not counting USA) and 90% of global population (86% not counting USA) in 2017.

• Renewable energy targets saw a steady increase throughout the last decade with coverage of countries in 2017 comparable to that of GHG targets.

• Key shifts in national measures coincide with landmark international events – an increase in legislation and strategy in the build-up to the Copenhagen Climate Conference and an increase in targets around the Paris Agreement – emphasizing the importance of the international process to maintaining national momentum.