ALBERT

Description: We assess uncertainties in projecting future changes in extreme storm surge height (SSH) based on typhoon data extracted from ensemble experiment results with four sea surface temperature (SST) conditions and three global warming scenarios using a single atmospheric global climate model. In particular, this study focus on typhoons passing around the Korean Peninsula (KP) defined as the region of 32 to 40° N and 122 to 132° E. It is predicted the number of the typhoons affecting the KP will decrease by 4~73% while their strength will increase by 0.8~1.4% under the given future conditions. The locations of genesis and lysis of the typhoons are expected to be shifted towards the northwest and northeast for all ensemble experiment conditions, respectively. However, the extent of their change varies depending on the future SST and global warming conditions. Storm surge simulations were carried out by using predicted typhoon data as an external force. It is found that future SST patterns and climate warming scenarios affect future typhoon characteristics, which influences values of extreme SSH and locations of the vulnerable area to storm surge under the future climate conditions. In particular, the values of extreme SSH and the locations of the vulnerable area to storm surge appear to be strongly influenced by both pathway and frequency of intense typhoons.

Description: Here, we investigate the seasonal variability in the dissolved inorganic carbon (DIC) cycle in the Northwest Pacific using a high-resolution biogeochemical and carbon model coupled with an operational ocean model. Results show that the contribution to DIC from air–sea CO2 exchange is generally offset by vertical mixing at the surface at all latitudes, with some seasonal variation. Biological processes in subarctic regions are evident at the surface, whereas in the subtropical region these processes take place within the euphotic layer and then DIC consumption deepens southward with latitude. Such latitudinal differences in biological processes lead to marked horizontal and vertical contrasts in the distribution of DIC, with modulation by horizontal and vertical advection–diffusion processes.

Description: Previous observational and modeling studies indicate that the wintertime North Pacific Oscillation (NPO) could significantly impact the following winter El Niño-Southern Oscillation (ENSO) variability via the seasonal footprinting mechanism (SFM). This study explores climate projections of this winter NPO-ENSO relation in a warming climate based on a 50-member large ensemble of climate simulations conducted with the second-generation Canadian Earth System Model (CanESM2). The ensemble mean of the 50 members can well reproduce the observed winter NPO pattern, the NPO-ENSO relationship, and the SFM process over the historical period 1950–2003. These 50 members are then employed to examine climate projections of the NPO-ENSO connection over the anthropogenic forced period 2020–2073. Results indicate that there exists a large spread of projected NPO-ENSO connections across these 50 ensemble members due to internal climate variability. Internal climate variability brings uncertainties in the projection of the winter NPO-ENSO connection originally seen in projected changes of the subtropical center of the winter NPO. The spread of projections of winter NPO-associated atmospheric anomalies over the subtropical North Pacific further results in various responses in the projections of winter and spring precipitation anomalies over the tropical North Pacific, as well as spring zonal wind anomalies over the tropical western Pacific, which eventually lead to uncertainties in the projection of the sea surface temperature anomalies in the tropical central-eastern Pacific from the following summer to winter.

Description: The interdisciplinary exchange in climate engineering research offers a unique opportunity to make assumptions more explicit for such research projects. While making assumptions explicit is the standard in all disciplinary sciences, some assumptions in the context of societal challenges can only be usefully unveiled, discussed, and verified from the perspective of other research disciplines. Results from successful interdisciplinary collaborations are then more accessible and more generalizable to actors beyond the confines of the academic community. We aim to illustrate how interdisciplinary exchange helps to unveil assumptions in research endeavors and why this is important for successful interdisciplinary collaborations. We therefore follow different stages of the German Priority Program on Climate Engineering (SPP 1689), which we use as an example case of a successful interdisciplinary project. SPP 1689 focused on risks, challenges, and opportunities of Climate Engineering from the perspectives of numerous disciplines. Major results were that the initial assessments of technologies had to be sobered, the consideration of trade-offs is crucial for the potential assessment, and governance issues appeared larger than previously considered. From the reflections of SPP 1689, we conclude with three lessons learned: (1) The project profited from egalitarian organizational structures and communicative practices, preventing the predominance from single disciplines. (2) Within the project continuous efforts were undertaken to foster interdisciplinary understanding. In addition, the flexible project structure allowed for the accommodation of research needs arising as a result of these exchanges. (3) SPP 1689 offered early career researchers a platform for professional exchange on common challenges and best practices of being a part of an interdisciplinary research project.

Description: Climate change is threatening food security in many tropical countries, where a large proportion of food is produced by vulnerable smallholder farmers. Interventions are available to offset many of the negative impacts of climate change on agriculture, and they can be tailored to local conditions often through relative modest investments. However, little quantitative information is available to guide investment or policy choices at a time when countries and development agencies are under pressure to implement policies that can help achieve Sustainable Development Goals while coping with climate change. Among smallholder adaptation options, developing seeds resilient to current and future climate shocks expected locally is one of the most important actions available now. In this paper, we used national and local data to estimate the costs of climate change to smallholder farmers in Malawi and Tanzania. We found that the benefits from adopting resilient seeds ranged between 984 million and 2.1 billion USD during 2020–2050. Our analysis demonstrates the benefits of establishing and maintaining a flexible national seed sector with participation by communities in the breeding, delivery, and adoption cycle.

Description: Uranium groundwater anomalies, observed before the L’Aquila earthquake (April 6th, 2009) and before the seismic swarm, which occurred in the second half of 2010, represent a key geochemical signal of a progressive increase of deep fluids fluxes at middle–lower crustal levels associated with the geodynamics of the earthquake. In this paper, temporal variations of uranium groundwater are studied in association with the seismic pattern around Gran Sasso National Laboratory (LNGS-INFN). The normalized seismic energy release and the number of earthquakes are analyzed in detail by means of monthly sliding time windows. They are compared with uranium anomalies to highlight any possible correlation.

Description: We report the result of a 2010 survey of the effects on the Iranian coastline of the tsunami which followed the earthquake of 27 November 1945 ( M 0  = 2.8 × 10 28  dyn cm; M w  = 8.2), the only large event recorded along the Makran subduction zone since the onset of instrumental seismology. Based on the interview of elderly survivors of the event, we obtained a database of nine values of run-up or splash amplitudes on a segment of shore extending 280 km from Souraf in the West to Pasabandar near the Pakistani border, and ranging in vertical amplitude from 2.3 to 13.7 m. Witness reports are consistent with a significant delay (estimated at ~2.5 h) of the tsunami waves, suggesting that they were generated by an ancillary phenomenon, such as a landslide triggered by the earthquake. None of our witnesses bore ancestral memory of comparable events in the past, suggesting that reported predecessors to the 1945 earthquake may have been smaller in size. The survey also allowed the compilation of previously unreported data concerning the effects of the 2004 Sumatra–Andaman tsunami.

Description: Multi-scale scratch analysis on a regional gravity field is a new data processing system for depicting three-dimensional density structures and tectonic features. It comprises four modules including the spectral analysis of potential fields, multi-scale wavelet analysis, density distribution inversion, and scratch analysis. The multi-scale scratch analysis method was applied to regional gravity data to extract information about the deformation belts in the Qinghai-Tibet Plateau, which can help reveal variations of the deformation belts and plane distribution features from the upper crust to the lower crust, provide evidence for the study of three-dimensional crustal structures, and define distribution of deformation belts and mass movement. Results show the variation of deformation belts from the upper crust to the lower crust. The deformation belts vary from dense and thin in the upper crust to coarse and thick in the lower crust, demonstrating that vertical distribution of deformation belts resembles a tree with a coarse and thick trunk in the lower part and dense and thin branches at the top. The dense and thin deformation areas in the upper crust correspond to crustal shortening areas, while the thick and continuous deformation belts in the lower crust indicate the structural framework of the plateau. Additionally, the lower crustal deformation belts recognized by the multi-scale scratch analysis coincide approximately with the crustal deformation belts recognized using single-scale scratch analysis. However, deformation belts recognized by the latter are somewhat rough while multi-scale scratch analysis can provide more detailed and accurate results.

Description: It is firmly established in the hydrologic literature that flooding depends on both antecedent watershed wetness and precipitation. One could phrase this relationship as “heavy precipitation does not necessarily lead to high stream discharge”, but rarely do studies directly affirm this statement. We have observed several non-hydrologists mistake trends in heavy precipitation as a proxy for trends in riverine flooding. If the relationship between heavy precipitation and high discharge was more often explicitly presented, heavy precipitation may less often be misinterpreted as a proxy for discharge. In this paper, we undertake such an analysis for 390 watersheds across the contiguous U.S. We found that 99th percentile precipitation only results in 99th percentage discharge 36 % of the time. However, when conditioned on soil moisture from the Variable Infiltration Capacity model, 62 % of 99th percentile precipitation results in 99th percentile discharge during wet periods and only 13 % during dry periods. When relating trends in heavy precipitation to hydrologic response, precipitation data should, therefore, be segregated based on concurrent soil moisture. Taking this approach for climate predictions, we found that CMIP-5 atmosphere–ocean global circulation model (AOGCM) simulations for a RCP 6.0 forcing project increases in concurrence of greater than median soil wetness and extreme precipitation in the northern United States and a decrease in the south, suggesting northern regions could see an increase in very high discharges while southern regions could see decreases despite both regions having an increase in extreme precipitation. While the actual outcome is speculative given the uncertainties of the AOGCM’s, such an analysis provides a more sophisticated framework from which to evaluate the output as well as historic climate data.

Description: Probabilistic event attribution (PEA) is an important tool for assessing the contribution of climate change to extreme weather events. Here, PEA is applied to explore the climate attribution of recent extreme heat events in California’s Central Valley. Heat waves have become progressively more severe due to increasing relative humidity and nighttime temperatures, which increases the health risks of exposed communities, especially Latino farmworkers and other socioeconomically disadvantaged communities. Using a superensemble of simulations with the Hadley Centre Regional Model (HadRM3P), we find that (1) simulations of the hottest summer days during the 2000s were twice as likely to occur using observed levels of greenhouse gases than in a counterfactual world without major human activities, suggesting a strong relationship between heat extremes and the increase in human emissions of greenhouse gases, (2) detrimental impacts of heat on public health-relevant variables, such as the number of days above 40 °C, can be quantified and attributed to human activities using PEA, and (3) PEA can serve as a tool for addressing climate justice concerns of populations within developed nations who are disproportionately exposed to climate risks.

Description: The complexity of the modeling of the rotational motion of the Earth in space has produced that no single theory has been adopted to describe it in full. Hence, it is customary using at least a theory for precession and another one for nutation. The classic approach proceeds by deriving some of the fundamental parameters from the precession theory, like, e.g., the dynamical ellipticity \(H_{\mathrm{d}}\) , and then using those values in the nutation theory. The former IAU 1976 precession and IAU 1980 nutation theories followed that scheme. Along with the improvement of the accuracy of the determination of Earth orientation parameters, IAU 1980 was superseded by IAU2000, based on the application of the MHB2000 transfer function to the previous rigid Earth analytical theory REN2000. The latter was derived while the precession model IAU 1976 was still in force, therefore it used the corresponding values for some of the fundamental parameters, as the precession rate, associated to the dynamical ellipticity. The new precession model P03 was adopted as IAU 2006. That change introduced some inconsistency since P03 used different values for some of the fundamental parameters that MHB2000 inherited from REN2000. Besides, the derivation of the basic Earth parameters of MHB2000 itself comprised a fitted variation of the dynamical ellipticity adopted in the background rigid theory. Due to the strict requirements of accuracy of the present and coming times, the magnitude of the inconsistencies originated by this twofold approach is no longer negligible as earlier, hence the need of discussing the effects of considering slightly different values for \(H_\mathrm{d}\) in precession and nutation theories.

Description: Data assimilation is a critical component for short-range weather forecasting; a number of algorithms have been developed and applied for assimilation of different kind of observations. However, an important but less explored question is the (optimal) amount of observation for maximum improvement in forecasts through data assimilation. Because the meteorological fields at different spatial and temporal resolutions are not necessarily mutually independent, indefinite increase in resolution of observations may be ineffective; thus data optimality in this sense can be defined as the maximum resolution of observation beyond which no appreciable improvement occurs due to assimilation of data. Based on forecasts of seven events over a complex terrain (urban location, Delhi) with different combinations of observations, we show that improvement in forecast skill does not saturate even with assimilation of observations a few kilometers (〈10 km) apart. The improvement due to assimilation of data from each of the profilers is appreciable; however, the impact was generally the highest for assimilation of data from all the four profilers. Applicable strategies for observation system design over high-impact areas are discussed.

Description: People have calculated Rayleigh-wave phase velocities from vertical component of ambient seismic noise for several years. Recently, researchers started to extract Love waves from transverse component recordings of ambient noise, where “transverse” is defined as the direction perpendicular to a great-circle path or a line in small scale through observation sensors. Most researches assumed Rayleigh waves could be negligible, but Rayleigh waves can exist in the transverse component when Rayleigh waves propagate in other directions besides radial direction. In study of data acquired in western Junggar Basin near Karamay city, China, after processing the transverse component recordings of ambient noise, we obtain two energy trends, which are distinguished with Rayleigh-wave and Love-wave phase velocities, in the frequency–velocity domain using multichannel analysis of surface waves (MASW). Rayleigh waves could be also extracted from the transverse component data. Because Rayleigh-wave and Love-wave phase velocities are close in high frequencies (〉0.1 Hz), two kinds of surface waves might be merged in the frequency–velocity domain. Rayleigh-wave phase velocities may be misidentified as Love-wave phase velocities. To get accurate surface-wave phase velocities from the transverse component data using seismic interferometry in investigating the shallow geology, our results suggest using MASW to calculate real Love-wave phase velocities.

Description: Uruk archaeological site, which located in Al-Muthanna Governorate southern Iraq, was investigated by integrated geophysical methods, ground penetration radar (GPR) and electric resistivity tomography (ERT) to image the historical buried structures. The GPR images show large radar attributes characterized by its continuous reflections having different widths. GPR attributes at shallower depth are mainly representing the upper part of Babylonian Houses that can often be found throughout the study area. In addition, radargrams characterized objects such as buried items, buried trenches and pits which were mainly concentrated near the surface. The ERT results show the presence of several anomalies at different depths generally having low resistivities. It is clear that the first upper zone can be found throughout the whole area and it may represent the top zone of the Babylonian houses. This zone is characterized by its dry clay and sandy soil containing surface broken bricks and slag mixed with core boulders. The second one underneath the top shows a prominent lower resistivity zone. It is probably caused by the moisture content that reduces the resistivity. The thickness of this zone is not equal at all parts of the site. The third deeper zone typically represents the archaeological walls. Most of the main anomalies perhaps referred to the buried clay brick walls. The map of the archaeological anomalies distribution and 3D view of the foundations at the study area using GPR and ERT techniques clearly show the characteristics of the Babylonian remains. A contour map and 3D view of Uruk show that the archaeological anomalies are concentrated mainly at the NE part of the district with higher values of wall height that range between 6 and 8 m and reach to more than 10 m. At the other directions, there are fewer walls with lower heights of 4–6 m and reach in some places the wall foot.

Description: Extreme weather events are a significant cause of loss of life and livelihoods, particularly in vulnerable countries and communities in Africa. Such events or their probability of occurring may be, or are, changing due to climate change with consequent changes in the associated risks. To adapt to, or to address loss and damage from, this changing risk we need to understand the effects of climate change on extreme weather events and their impacts. The emerging science of probabilistic event attribution can provide scientific evidence about the contribution of anthropogenic climate change to changes in risk of extreme events. This research has the potential to be useful for climate change adaptation, but there is a need to explore its application in vulnerable developing countries, particularly those in Africa, since the majority of existing event attribution studies have focused on mid-latitude events. Here we explain the methods of, and implications of, different approaches to attributing extreme weather events in an African context. The analysis demonstrates that different ways of framing attribution questions can lead to very different assessments of change in risk. Crucially, defining the most appropriate attribution question to ask is not a science decision but one that needs to be made in dialogue with those stakeholders who will use the answers. This is true of all attribution studies but may be particularly relevant in a tropical context, suggesting that collaboration between scientists and policy-makers is a priority for Africa.

Description: We develop a methodology with which to assess the effects of policy instruments on the long-term abatement and costs of carbon capture and storage (CCS) technologies for coal power plants. Using an expert elicitation, historical data on the determinants of technological change in energy, values from the engineering literature, and demand estimates from an integrated assessment model, we simulate ranges of outcomes between 2025 and 2095. We introduce probability distributions of all important parameters and propagate them through the model to generate probability distributions of electricity costs, abatement costs, and CO 2 avoided over time. Carbon pricing has larger effects than R&D and subsidies. But much of the range of outcomes is driven by uncertainty in other parameters, such as capital costs and returns to scale. Availability of other low carbon technologies, particularly bioenergy with CCS affects outcomes. Subsidies have the biggest impacts when they coincide with expanding manufacturing scale of CCS components. Our results point to 4 parameters for which better information is needed for future work informing technology policy to address climate change: capital costs, demonstration plants, growth constraints, and knowledge spillovers among technologies.

Description: Future bitumen production in the Athabasca Oil Sands, one of the largest remaining reserves of petroleum on the planet, is a key factor in global climate policy and politics. Climate warming in the Athabasca River Basin (ARB) has the potential to limit future streamflow availability for aquatic ecosystem needs, as well as for water withdrawals in oil sands mining operations. This study applies the land surface model IBIS and the hydrological routing algorithm THMB, with forced output from CMIP5 global climate models, to examine the response of streamflow in the ARB to climate change this century. In comparison to the small impact of water withdrawals on streamflow, climate change impacts are projected to be the primary driver of future low flow occurrences. Although winter flows are most sensitive to water withdrawals under the historical hydroclimatological regime, future climate change is projected to increase winter flows and decrease summer flows instead, with the frequency of summer low flows projected to rise by up to 85 % in the highest future emissions scenario by the end of the century. A decline in water availability due to more frequent low flows could interrupt oil sands water withdrawals and subsequent daily bitumen production for an additional 2–3 months each year by mid-century. Adaptation to climate warming in the ARB will need to recognize these changing seasonal patterns of flow in order to maintain available flows for ecological needs and water withdrawals.

Description: The model based on rate- and state-dependent friction law reproduces the temporal decay of an aftershock sequence with the p  value of the Omori–Utsu law equal to 1, if we simply assume a constant stress rate over time. However, because p  values vary in real aftershock sequences, this model requires some modification. This study examined the effect of secondary aftershocks on the variety of the p  value. A large aftershock causes a stepwise stress increase in the aftershock area, and the expected seismicity rate derived from the friction law also increases abruptly. These multiple increases in the seismicity rate during its decay following a mainshock could cause variation in the apparent p  value. In this study, a model incorporating this idea is applied to two aftershock sequences observed in Japan and is shown to substantially modify the modeling of aftershock activity.

Description: Recent trends in the frequency and intensity of extreme weather events have raised the concern that climate change could increase flooding risks and property damage. However, a major challenge in attributing and projecting changes in disaster risk is that damage is influenced not only by the physical climate hazard, but also by non-climatic factors that shape exposure and vulnerability. Recent assessments of integrated disaster risk have been hampered by the paucity of literature analyzing local-scale interactions between hazard, exposure and vulnerability in the historical record. Here we develop an integrated empirical analysis of historical flood damage that emphasizes spatial and temporal heterogeneity in flood hazard, economic exposure and social vulnerability. Using the Midwestern United States as a testbed, we show that annual property damage from flooding is projected to increase by 13 to 17.4 % over the next two decades. At the state level, over half of the increase is driven by projected growth in housing units. However, at the county level, the dominant factor causing future damage varies, emphasizing the value of a fully integrated, spatially and temporally resolved approach to assessing flooding risk and control strategies.

Description: We present the analysis of the subsurface structure of the Auca Mahuida volcano based on high-resolution aeromagnetic data integrated with the available geological information. Most of the detected magnetic anomalies have a dipolar structure opposite to that of the present geomagnetic field. According to the available geochronological data and paleomagnetic measurements, the source bodies of Auca Mahuida mainly emplaced in the Matuyama reverse polarity chron. The Reduction-to-the-Pole map confirms that the magnetization direction is mainly reverse with only few anomalies normally magnetized. Two opposite, coexisting polarities do not allow to fully remove the dipolar character of the field in the Reduction-to-the-Pole transformation. Therefore, we model the measured anomaly field by applying analytical techniques that are independent of the magnetization direction. The obtained anomaly strikes and source geometries indicate an emplacement of intrusive bodies controlled by the regional faults affecting the Auca Mahuida basement and the sedimentary successions of the Neuquén basin. Magma upraised along these faults and fractures feeding the volcanic activity and subsequently crystallized. The averaged power spectrum and Euler Deconvolution indicate source depths consistent with those of the intrusions recognized in wells. Borehole data highlight the widespread presence of intrusive bodies below the Auca Mahuida central crater and the peripheral sectors at depth of 2 km below sea level. These bodies have played a major role in the thermal maturation of hydrocarbons and in the subsequent accumulation of oil below the volcano. The obtained results shed light on the Auca Mahuida feeding system and on the intrusions geometry, also pointing out the effectiveness of the magnetic prospecting in the oil industry even in presence of strong remanent magnetization.

Description: Considering the importance of snow and glaciers in the Himalayas for understanding the water cycle and for water resource management of the rivers originating from the Himalayan, interannual variability of snow accumulation process over Himalayas and surrounding region has been studied using snow water equivalent (SWE) data. Remote sensing data from National Snow and Ice Data Centre have been used. These data have been compared against ground (in situ) observations of SWE measured at several gauge stations in the Indian part of the Satluj River basin. Accumulated SWE from remote sensing data and ground observations in the Satluj River basin have good and significant correlation. These data have also been compared against the Climate Forecast System Reanalysis and the European Centre for Medium Range Weather Forecast reanalysis-Interim (ERA-I). Upper air and surface data from the reanalyses have also been used to examine the atmospheric conditions when snowfall occurs and snow accumulates for the season. In this study, it is found that there is large interannual variation in SWE over western Himalayas and Satluj River basin (domain of interest). During excess years of snowfall, strong westerly winds are observed at 500 hPa over India. In wind anomaly, a cyclonic circulation is seen over northern parts of India with a deep trough along Pakistan, Rajasthan and Gujarat region. As a consequence of this trough, a moisture convergence zone is established in the region leading to more amount of snowfall. At the same time, during excess snow accumulation years, the air temperature from the surface to 500 hPa is colder than other years enabling the fallen snow to accumulate through the season.

Description: Religious beliefs, an important element of culture, influence adaptation to climate change. Less understood is how changing beliefs shape the adaptive capacity of communities responding to climate change. In the last century sub-Saharan Africa has experienced a transformation in beliefs. Since 1900 Christians have increased 70-fold while in rural areas Traditional Beliefs and associated Traditional Ecological Knowledge (TEK) continue to influence the lived practices of vulnerable rural communities. Using two case studies of rural communities in Malawi (Bolero) and Zambia (Monze) we explore how Christianity and Traditional beliefs (and associated TEK) co-exist and assess if, and how, holding multiple belief systems affects climate-sensitive livelihood practices of food production. In Bolero we observed a lack of tensions between belief systems with Traditional leaders and elders noting the flexibility of adhering to both belief systems. In Monze however, basing livelihood decisions on the practice of rain-rituals resulted in strong tensions. In both communities elders noted their concern of how changing beliefs affect adherence to TEK management practices. We find that culture and beliefs play an important role in adaptive capacity but are not static. In the context of changing beliefs, adaptive capacity will be influenced by how different belief systems co-exist and how epistemological and intergenerational frictions are negotiated. As climate services become the focus of research and government interventions in vulnerable regions, avoiding culturally and economically expensive mal-adaptation will require giving attention to the complexity and dynamism of changing religious landscapes.

Description: On June 22, 1932, a 10- to 12-m-high tsunami wave struck ~60 km off the Mexican Pacific coast. The associated earthquake that apparently produced this tsunami is questionable because of its relatively small magnitude ( M s  = 6.9) to produce such tsunami heights. Historical documents, survivor testimony, tsunami catalogs, a post-tsunami survey report, together with geomorphological interpretation of the continental shelf and slope, and numerical modeling were combined to characterize the tsunami parameters. Our results suggest that recorded maximum tsunami wave height, horizontal inundation, arrival time, directivity, effects, and damage are compatible with those characteristics related to an underwater landslide tsunami. The associated landslide (slump) is 4.2 km long, 3.9 km wide, 0.448 km thick, and is located in the upper continental shelf of the Armería Canyon. Elucidating the cause and mechanisms of the near-field 1932 tsunami would aid in considering a wider spectrum of tsunami sources in hazard mitigation programs of the Mexican Pacific coast.

Description: The main objective of this study is the determination of the Moho discontinuity in the Hellenic area based on gravity data inversion. High-resolution (2 arcmin) and accuracy (±2 to ±3 mGal) gravity data were used in the computations following the Parker–Oldenburg iterative method, and a low-pass filter was applied to gravity information towards the convergence of the final solution. To determine the cut-off wavenumber of the filter, we tested different mean depths and density contrasts of the crust and the mantle (Mohorovičić discontinuity). The selected density contrast and mean depth of the Mohorovičić discontinuity are those which agree with the Moho depth interpreted from deep seismic imaging data. By comparing the Moho depth estimated, covering both land and marine areas and including the Ionian and Aegean Sea, with those interpreted from previous studies, it is shown that our solution is consistent with the available seismic data interpretation. Moreover, the resolution of the gravity data and the appropriate filtering used in this study contributed to the representation of local features of the Moho discontinuity. Finally, area-dependent discrepancies detected between the Moho depths of the current solution and those derived from previous studies are extensively discussed.

Description: Not much attention is given to direct wave arrivals in marine seismic data that are acquired for petroleum exploration and prospecting. These direct arrivals are usually muted out in routine seismic data processing. In the present study, we process these direct arrivals to accurately estimate soundspeed in near-surface seawater and invert for sea surface temperature. The established empirical equation describing the relationships among temperature, salinity, pressure and soundspeed is used for the inversion. We also discuss processing techniques, such as first-break picking and cross-correlation for the estimation of soundspeed, that are well known among petroleum-industry geophysicists. The accuracy of the methods is directly linked to the data quality and signal processing. The novelty in our approach is in the data conditioning, which consists essentially of spectral balancing based on a wavelet transform that compensates for spherical spreading and increases the signal-to-noise ( S / N ) ratio. The 2D seismic data used in this paper are from the offshore Krishna-Godavari Basin east of India. We observe a significantly higher soundspeed of 1545 m/s for near-surface water than the commonly used value of ~1500 m/s. The estimated temperature (from velocity) is about 30 °C. Interestingly, the estimated temperature matches well with the temperature recorded in the CTD profile acquired in the study area during the month of May, the month corresponding to the acquisition of seismic data. Furthermore, the estimated temperatures during different times of data acquisition correlate well with the expected diurnal variation in temperature.

Description: In the present study, advanced research WRF (ARW) model is employed to simulate convective thunderstorm episodes over Kharagpur (22°30′N, 87°20′E) region of Gangetic West Bengal, India. High-resolution simulations are conducted using 1 × 1 degree NCEP final analysis meteorological fields for initial and boundary conditions for events. The performance of two non-local [Yonsei University (YSU), Asymmetric Convective Model version 2 (ACM2)] and two local turbulence kinetic energy closures [Mellor–Yamada–Janjic (MYJ), Bougeault–Lacarrere (BouLac)] are evaluated in simulating planetary boundary layer (PBL) parameters and thermodynamic structure of the atmosphere. The model-simulated parameters are validated with available in situ meteorological observations obtained from micro-meteorological tower as well has high-resolution DigiCORA radiosonde ascents during STORM-2007 field experiment at the study location and Doppler Weather Radar (DWR) imageries. It has been found that the PBL structure simulated with the TKE closures MYJ and BouLac are in better agreement with observations than the non-local closures. The model simulations with these schemes also captured the reflectivity, surface pressure patterns such as wake-low, meso-high, pre-squall low and the convective updrafts and downdrafts reasonably well. Qualitative and quantitative comparisons reveal that the MYJ followed by BouLac schemes better simulated various features of the thunderstorm events over Kharagpur region. The better performance of MYJ followed by BouLac is evident in the lesser mean bias, mean absolute error, root mean square error and good correlation coefficient for various surface meteorological variables as well as thermo-dynamical structure of the atmosphere relative to other PBL schemes. The better performance of the TKE closures may be attributed to their higher mixing efficiency, larger convective energy and better simulation of humidity promoting moist convection relative to non-local schemes.

Description: In western Mexico, the subduction of the Rivera and Cocos plates beneath the North America plate has deformed and fragmented the overriding plate, forming several structural rifts and crustal blocks. To obtain a reliable subsurface image of the continental crust and uppermost mantle in this complex area, we used P-wave arrivals of local earthquakes along with the Fast Marching Method tomography technique. We followed an inversion scheme consisting of (1) the use of a high-quality earthquake catalog and corrected phase picks, (2) the selection of earthquakes using a maximum location error threshold, (3) the estimation of an improved 1-D reference velocity model, and (4) the use of checkerboard testing to determine the optimum configuration of the velocity nodes and inversion parameters. Surprisingly, the tomography results show a very simple δVp distribution that can be described as being controlled by geologic structures formed during two stages of the separation of the Rivera and Cocos plates. The earlier period represents the initial stages of the separation of the Rivera and Cocos plates beneath western Mexico; the later period represents the more advanced stage of rifting where the Rivera and Cocos plates had separated sufficiently to allow melt to accumulate below the Colima Volcanic complex. During the earlier period (14 or 10–1.6 Ma), NE–SW-oriented structures/lineaments (such as the Southern Colima Rift) were formed as the two plates separated. During the second period (1.6 Ma to the present), the deformation is attributed to magma, generated within and above the tear zone between the Rivera and Cocos plates, rising beneath the region of the Colima Volcanic Complex. The rising magma fractured the overlying crust, forming a classic triple-rift junction geometry. This triple-rift system is confined to the mid- to lower crust perhaps indicating that this rifting process is still in an early stage. This fracturing, along with fluid circulation and associated heat advection within the fractures, can easily explain the observed distribution of δVp, as well as many of the results of previous seismological studies. Also surprisingly, we find no evidence at deep crustal depths to support either a trenchward migration of the volcanic arc or toroidal asthenospheric flow through the slab tears bounding the Jalisco Block to the NW and SE.

Description: Identifying correct modes of surface waves and picking accurate phase velocities are critical for obtaining an accurate S-wave velocity in MASW method. In most cases, inversion is easily conducted by picking the dispersion curves corresponding to different surface-wave modes individually. Neighboring surface-wave modes, however, will nearly meet (kiss) at some frequencies for some models. Around the frequencies, they have very close roots and energy peak shifts from one mode to another. At current dispersion image resolution, it is difficult to distinguish different modes when mode-kissing occurs, which is commonly seen in near-surface earth models. It will cause mode misidentification, and as a result, lead to a larger overestimation of S-wave velocity and error on depth. We newly defined two mode types based on the characteristics of the vertical eigendisplacements calculated by generalized reflection and transmission coefficient method. Rayleigh-wave mode near the kissing points (osculation points) change its type, that is to say, one Rayleigh-wave mode will contain different mode types. This mode type conversion will cause the mode-kissing phenomenon in dispersion images. Numerical tests indicate that the mode-kissing phenomenon is model dependent and that the existence of strong S-wave velocity contrasts increases the possibility of mode-kissing. The real-world data shows mode misidentification caused by mode-kissing phenomenon will result in higher S-wave velocity of bedrock. It reminds us to pay attention to this phenomenon when some of the underground information is known.

Description: In this paper, we report on a preliminary investigation into a semi-empirical method for derivation of depth–age relationship for oceanic lithosphere. The global 30-arcsecond bathymetry data from the General Bathymetric Charts of the Oceans (GEBCO) were corrected for (1) sediment thickness using the Total Sediment Thickness of the World’s Oceans and Marginal Seas and (2) isostasy. The corrected bathymetry was processed to obtain the empirical bathymetric curve, the solution computed with 50 m elevation bin. Subsequently, the data-based curve was approximated with the optimal polynomial model. By combining the model with a formula for derivative of area with respect to age, we obtained the approximate differential equation for depth–age relationship. We solved the equation numerically. The solution was compared with (1) depth–age relationships derived empirically using the combination of the corrected GEBCO bathymetry with digital isochrons of the oceans, (2) Parsons Sclater Model (PSM) and (3) Global Depth Heatflow model (GDH1). In the new depth–age curve, three sections with specific relationships of ocean depth versus age of the crust are identified: (1) moderate increase in depth from 2500 to 5900 m for lithospheric ages 0–118 Ma, (2) more pronounced increase in depth from 5900 to 6700 m for the lithosphere 118–147 Ma old, (3) stabilization of ocean depth at 6700–6760 m for the lithosphere older than 147 Ma. The fit to empirical data as well as PSM and GDH1 models is good for the first section, but rather imperfect for the other two. Reasons for mismatches are complex and probably different for dissimilar sections of the curve.

Description: Fog affects human life in a number of ways by reducing the visibility, hence affecting critical infrastructure, transportation, tourism or by the formation of frost, thus harming the standing crops. Smog is becoming a regular phenomenon in urban areas which is highly toxic to humans. Delhi was chosen as the area of study as it encounters all these hazards of fog stated apart from other political and economic reasons. The complex relationship behind the parameters and processes behind the formation of fog makes it extremely difficult to model and forecast it accurately. It is attempted to forecast the fog and understand its dynamics through a statistical downscaling technique of artificial neural network which is deemed accurate for short-term forecasting and usually outperform time-series models. The backpropagation neural network, which is a gradient descent algorithm where the network weights are moved along the negative of the gradient of the performance function, has been used for our analysis. Indian Meteorological Department (IMD) supported National Oceanic and Atmospheric Administration (NOAA) data had been used for carrying out the simulations. The model was found to have high accuracy but lacking in skill. An attempt has been made to present the data in a binary form by determining a threshold by the contingency table approach followed by its critical analysis. It is found that the calculation of an optimum threshold was also difficult to fix as the parameters of fog formation on which the model has been has been trained had shown some changes in their trend over a period of time.

Description: The data from suite of in situ sensors, passive and active remote sensing instruments dedicated to document simultaneously radiative and thermo-dynamical processes driving the fog life cycle at the SIRTA Observatory (instrumented site for atmospheric remote sensing research) near Paris during two periods of 6 months are analysed. The study focuses on the analysis of the relative role of key physical processes and their interactions during fog formation, development and dissipation phases. This work presents, from analysis of detailed observations, the range of values that critical parameters have to take for fog and quasi-fog formation. In our study, we consider fog (horizontal visibility lower than 1 km, a dataset of 300 h) and quasi-fog (horizontal visibility ranging from 1 to 2 km, a dataset of 400 h) events induced by radiative cooling (53 events) and stratus lowering (64 events). For the radiative fog events, (with radiative cooling during prefog conditions), we note that the longwave net radiative flux (around −60 ± 5 W/m 2 ) induces a cooling of the surface layer. The vertical structure of this cooling is controlled by dynamics, that is, wind shear and horizontal and vertical velocities. In case of very low mixing (wind speed below 0.6 m/s), the thermal stability is very strong with a temperature inversion around 3.5 °C for 10 m and a humidity gradient reaching 10 % preventing vertical development of the fog layer. For stratus-lowering fog events, the altitude of the stratus layer, the vertical mixing and the absolute value of humidity are driving parameters of the fog formation. Our statistical analysis shows that a stratus cloud with a cloud base around 170 m and with a small cloud-base subsidence rate of 50 m/h leads to fog, whereas a stratus cloud with a base around 800 m agl, with a larger cloud-base subsidence rate of 190 m/h conducts to quasi-fog situations with an important increase of the stratus liquid water path.

Description: The isostatic modeling represents one of the most useful “geological” reduction methods of the gravity field. With the isostatic correction, it is possible to remove a significant part of the effect of deep density heterogeneity, which dominates in the Bouguer gravity anomalies. Although there exist several isostatic compensation schemes, it is usually supposed that a choice of the model is not an important factor to first order, since the total weight of compensating masses remains the same. We compare two alternative models for the Arabian plate and surrounding area. The Airy model gives very significant regional isostatic anomalies, which cannot be explained by the upper crust structure or disturbances of the isostatic equilibrium. Also, the predicted “isostatic” Moho is very different from existing seismic observations. The second isostatic model includes the Moho, which is based on seismic determinations. Additional compensation is provided by density variations within the lithosphere (chiefly in the upper mantle). According to this model, the upper mantle under the Arabian Shield is less dense than under the Platform. In the Arabian platform, the maximum density coincides with the Rub’ al Khali, one of the richest oil basin in the world. This finding agrees with previous studies, showing that such basins are often underlain by dense mantle, possibly related to an eclogite layer that has caused their subsidence. The mantle density variations might be also a result of variations of the lithosphere thickness. With the combined isostatic model, it is possible to minimize regional anomalies over the Arabian plate. The residual local anomalies correspond well to tectonic structure of the plate. Still very significant anomalies, showing isostatic disturbances of the lithosphere, are associated with the Zagros fold belt, the collision zone of the Arabian and Eurasian plates.

Description: Climate-related extreme weather events can result in the loss of drinking water access. We assessed the relative vulnerability of 3143 United States (U.S.) counties to loss of drinking water access due to droughts, floods, and cyclones. Five vulnerability assessment models from the literature were compared, each differing in the aggregation method used to combine the three determinants of vulnerability (V) – exposure (E), sensitivity (S), and adaptive capacity (AC). Exposure scores were calculated using historical occurrence data, sensitivity scores were determined from the intrinsic resilience of the drinking water technologies, and adaptive capacity scores were calculated from nine socioeconomic indicators. Our results showed that models V  =  E  +  S  +  AC and V  =  E  +  S – AC were the same, as were models V  =  E  ×  S  ×  AC and V  =  E  ×  S  ÷  AC . Between these two model forms (form 1: V  =  E  +  S  +  AC and V  =  E  +  S – AC ; form 2: V  =  E  ×  S  ×  AC and V  =  E  ×  S  ÷  AC ), scores from one model form could be used to predict scores from the second model form, with R-squared values ranging from 0.61 to 0.82 depending on the extreme weather event type. A fifth model, V  = ( E – AC ) ×  S was not found to correlate with any of the other four models. We used V  =  E  +  S  +  AC as our reference model as this resulted in a more uniform distribution of counties in each of the five intervals of vulnerability. Comparing the vulnerability scores identified the counties with greatest vulnerability to losing access to drinking water due to floods, droughts, and cyclones. Our results can be used to inform evidence-based decisions such as allocation of resources and implementation of adaptation strategies.

Description: Ambient noise correlation analyses are largely used in seismology to map heterogeneities and to monitor the temporal evolution of seismic velocity changes associated mostly with stress field variations and/or fluid movements. Here we analyse a small earthquake swarm related to a main m R 3.7 intraplate earthquake in North-East of Brazil to study the corresponding post-seismic effects on the medium. So far, post-seismic effects have been observed mainly for large magnitude events. In our study, we show that we were able to detect localized structural changes even for a small earthquake swarm in an intraplate setting. Different correlation strategies are presented and their performances are also shown. We compare the classical auto-correlation with and without pre-processing, including 1-bit normalization and spectral whitening, and the phase auto-correlation. The worst results were obtained for the pre-processed data due to the loss of waveform details. The best results were achieved with the phase cross-correlation which is amplitude unbiased and sensitive to small amplitude changes as long as there exist waveform coherence superior to other unrelated signals and noise. The analysis of 6 months of data using phase auto-correlation and cross-correlation resulted in the observation of a progressive medium change after the major recorded event. The progressive medium change is likely related to the swarm activity through opening new path ways for pore fluid diffusion. We further observed for the auto-correlations a lag time frequency-dependent change which likely indicates that the medium change is localized in depth. As expected, the main change is observed along the fault.

Description: The strong development of tsunami instrumentation in the past decade now provides observations of tsunami wave propagation in most ocean basins. This evolution has led to the wide use of tsunami data to image the complexity of earthquake sources. In particular, the 2011 M w 9.0 Tohoku-Oki earthquake is the first mega-event for which such a tsunami instrumentation network was available with an almost complete azimuthal coverage. Source inversion studies have taken advantage of these observations which add a lot of constrain on the solutions, especially in the shallow part of the fault models where other standard data sets tend to lack resolution: while on-land data are quite insensitive to slip on the often-distant shallow part of a subduction fault interface, tsunami observations are directly sensitive to the shallowest slip. And it is in this shallow portion that steep bathymetry combined with horizontal motion, the so-called bathymetry effect, can contribute to the tsunami excitation, in addition to the direct vertical sea-bottom deformation. In this study, we carefully investigate the different steps involved in the calculation of this bathymetry effect, from the initial sea-floor deformation to the prediction of the tsunami records, and evaluate its contribution across the main subduction zones of the world. We find that the bathymetry effect locally exceeds 10 % of the tsunami excitation in all subduction zones and 25 % in those known to produce the largest tsunami, either from mega- or tsunami- earthquakes. We then show how the bathymetry effect can modify the tsunami wave predictions, with time shifts of the wavefront and amplitudes sometimes varying by a factor of two. If the bathymetry effect can have a strong impact on the simulated tsunami, it will also affect the solution of the finite-fault slip inversion. We illustrate this later aspect in the case of the Tohoku-Oki earthquake. We find that not accounting for the bathymetry effect will not necessarily cause strong variations in the spatial extent of the inferred coseismic rupture but can severely distort the solution. We also find that the bathymetry effect improves the consistency of the slip model inverted from tsunami data with seafloor geodesy observations, implying that taking the bathymetry effect into account reduces the epistemic uncertainties on tsunami modeling. Implementing this easily quantifiable effect in the tsunami early warning system could thus lead to improved estimates of the tsunami impact across ocean basins.

Description: We determined source spectral functions, Q and site effects using regional records of body waves from the October 19, 2013 ( M w  = 6.6) earthquake and eight aftershocks located 90 km east of Loreto, Baja California Sur, Mexico. We also analyzed records from a foreshock with magnitude 3.3 that occurred 47 days before the mainshock. The epicenters of this sequence are located in the south-central region of the Gulf of California (GoC) near and on the Farallon transform fault. This is one of the most active regions of the GoC, where most of the large earthquakes have strike–slip mechanisms. Based on the distribution of the aftershocks, the rupture propagated northwest with a rupture length of approximately 27 km. We calculated 3-component P- and S-wave spectra from ten events recorded by eleven stations of the Broadband Seismological Network of the GoC (RESBAN). These stations are located around the GoC and provide good azimuthal coverage (the average station gap is 39°). The spectral records were corrected for site effects, which were estimated calculating average spectral ratios between horizontal and vertical components (HVSR method). The site-corrected spectra were then inverted to determine the source functions and to estimate the attenuation quality factor Q . The values of Q resulting from the spectral inversion can be approximated by the relations \(Q_{\text{P}} = 48.1 \pm 1.1 f^{0.88 \pm 0.04}\) and \(Q_{\text{S}} = 135.4 \pm 1.1 f^{0.58 \pm 0.03}\) and are consistent with previous estimates reported by Vidales-Basurto et al. (Bull Seism Soc Am 104:2027–2042, 2014 ) for the south-central GoC. The stress drop estimates, obtained using the ω 2 model, are below 1.7 MPa, with the highest stress drops determined for the mainshock and the aftershocks located in the ridge zone. We used the values of Q obtained to recalculate source and site effects with a different spectral inversion scheme. We found that sites with low S-wave amplification also tend to have low P-wave amplification, except for stations BAHB, GUYB and SFQB, located on igneous rocks, where the P-wave site amplification is higher.

Description: We present a generic 1D forward modeling and inversion algorithm for transient electromagnetic (TEM) data with an arbitrary horizontal transmitting loop and receivers at any depth in a layered earth. Both the Hankel and sine transforms required in the forward algorithm are calculated using the filter method. The adjoint-equation method is used to derive the formulation of data sensitivity at any depth in non-permeable media. The inversion algorithm based on this forward modeling algorithm and sensitivity formulation is developed using the Gauss–Newton iteration method combined with the Tikhonov regularization. We propose a new data-weighting method to minimize the initial model dependence that enhances the convergence stability. On a laptop with a CPU of i7-5700HQ@3.5 GHz, the inversion iteration of a 200 layered input model with a single receiver takes only 0.34 s, while it increases to only 0.53 s for the data from four receivers at a same depth. For the case of four receivers at different depths, the inversion iteration runtime increases to 1.3 s. Modeling the data with an irregular loop and an equal-area square loop indicates that the effect of the loop geometry is significant at early times and vanishes gradually along the diffusion of TEM field. For a stratified earth, inversion of data from more than one receiver is useful in noise reducing to get a more credible layered earth. However, for a resistive layer shielded below a conductive layer, increasing the number of receivers on the ground does not have significant improvement in recovering the resistive layer. Even with a down-hole TEM sounding, the shielded resistive layer cannot be recovered if all receivers are above the shielded resistive layer. However, our modeling demonstrates remarkable improvement in detecting the resistive layer with receivers in or under this layer.

Description: In this research, remotely sensed data has been used to estimate the volume of pyroclastic deposits and analyze morphological changes that have resulted from the eruption of Sinabung volcano. Topographic information was obtained from these data and used for rapid mapping to assist in the emergency response. Topographic information and change analyses (pre- and syn- eruption) were conducted using digital elevation models (DEMs) for the period 2010–2015. Advanced spaceborne thermal emission and reflection radiometer (ASTER) global digital elevation model (GDEM) data from 2009 were used to generate the initial DEMs for the condition prior to the eruption of 2010. Satellite pour l’observation de la terre 6 (SPOT 6) stereo images acquired on 21 June 2015 and were used to make a DEM for that time. The results show that the estimated total volume of lava and pyroclastic deposits, produced during the period 2010 to mid-2015 is approximately 2.8 × 10 8  m 3 . This estimated volume of pyroclastic deposits can be used to predict the magnitude of future secondary lahar hazards, which are also related to the capacity of rivers in the area. Morphological changes are illustrated using cross-sectional analysis of the deposits, which are currently deposited to the east, southeast and south of the volcano. Such analyses can also help in forecasting the direction of the future flow hazards. The remote sensing and analysis methods used at Sinabung can also be applied at other volcanoes and to assess the threats of other types of hazards such as landslides and land subsidence.

Description: It is well known that small glaciers of mid latitudes and especially those located at low altitude respond suddenly to climate changes both on local and global scale. For this reason their monitoring as well as evaluation of their extension and volume is essential. We present a ground penetrating radar (GPR) dataset acquired on September 23 and 24, 2013 on the Triglav glacier to identify layers with different characteristics (snow, firn , ice, debris) within the glacier and to define the extension and volume of the actual ice. Computing integrated and interpolated 3D using the whole GPR dataset, we estimate that at the moment of data acquisition the ice area was 3800 m 2 and the ice volume 7400 m 3 . Its average thickness was 1.95 m while its maximum thickness was slightly more than 5 m. Here we compare the results with a previous GPR survey acquired in 2000. A critical review of the historical data to find the general trend and to forecast a possible evolution is also presented. Between 2000 and 2013, we observed relevant changes in the internal distribution of the different units (snow, firn , ice) and the ice volume reduced from about 35,000 m 3 to about 7400 m 3 . Such result can be achieved only using multiple GPR surveys, which allow not only to assess the volume occupied by a glacial body, but also to image its internal structure and the actual ice volume. In fact, by applying one of the widely used empirical volume-area relations to infer the geometrical parameters of the glacier, a relevant underestimation of ice-loss would be achieved.

Description: Implementing an effective climate policy is one of the main challenges for the future. Curbing greenhouse gas emissions can prevent future irreversible impacts of climate change. Climate policy is therefore crucial for present and future generations. Nonetheless, one may wonder whether future economic and social development could be harmed by climate policy. This paper addresses this question by examining recent developments in international climate policy and considering different levels of cooperation that may arise in light of the outcomes of the Conference of the Parties held in Doha. The paper analyses how various climate policy scenarios would enhance sustainability and whether there is a trade-off between climate policy and economic development and social cohesion. This is done by using a new comprehensive indicator, the FEEM Sustainability Index (FEEM SI), which aggregates several economic, social, and environmental indicators. The FEEM SI is built into a recursive-dynamic computable general equilibrium model of the world economy, thus offering the possibility of projecting all indicators into the future and of delivering a perspective assessment of sustainability under different future climate policy scenarios. We find that the environmental component of sustainability improves at the regional and world level thanks to the implementation of climate policies. Overall sustainability increases in all scenarios since the economic and social components are affected negatively yet marginally. This analysis does not include explicitly climate change damages and this may lead to underestimating the benefits of policy actions. If the USA, Canada, Japan and Russia did not contribute to mitigating emissions, sustainability in these countries would decrease and the overall effectiveness of climate policy in enhancing global sustainability would be offset.

Description: This study provides the first attempt in quantifying the uncertainties in future urban climate projections due to regional climate models and metropolitan-scale urban planning scenarios. Targeted for the 2050s Augusts in Tokyo, Japan, dynamical downscaling simulations are conducted using two regional climate models, the WRF and NHRCM models, both downscaled from the global climate model MIROC5 under the RCP4.5 scenario. Both regional climate models are coupled with appropriate urban canopy models to accurately evaluate the urban climate. The projected 10-year mean temperature increases for the 2050s Augusts in the central Tokyo are roughly 2.4 °C and 2.2 °C, for the WRF and NHRCM models, respectively, with a roughly 0.2 °C difference between the two. Urban scenario experiments with the WRF model indicate that the compact city urban scenario can reduce the August mean temperature of surrounding residential areas by 0.4 °C, while the dispersed city scenario can increase the temperature by 0.1 °C. On the other hand, impact of urban scenarios on the temperature increase in central Tokyo is comparative or less than the surrounding areas. The impacts of urban scenario and regional climate model differences are larger in nighttime than in daytime, but are at most 0.6 °C. The results indicate that the uncertainties with the regional climate models and urban scenario are significantly less than those in emission scenarios or global climate model projections.

Description: The recent deployment of highly sensitive seafloor magnetometers coinciding with the deep solar minimum has provided excellent opportunities for observing tsunami electromagnetic signals. These fluctuating signals (periods ranging from 10–20 min) are generally found to be within \(\pm\) \(\sim\) 1 nT and coincide with the arrival of the tsunami waves. Previous studies focused on tsunami electromagnetic characteristics, as well as modeling the signal for individual events. This study instead aims to provide the time–frequency characteristics for a range of tsunami signals and a method to separate the data’s noise using additional data from a remote observatory. We focus on four Pacific Ocean events of varying tsunami signal amplitude: (1) the 2011 Tohoku, Japan event (M9.0), (2) the 2010 Chile event (M8.8), (3) the 2009 Samoa event (M8.0) and, (4) the 2007 Kuril Islands event (M8.1). We find possible tsunami signals in high-pass filtered data and successfully isolate the signals from noise using a cross-wavelet analysis. The cross-wavelet analysis reveals that the longer period signals precede the stronger, shorter period signals. Our results are very encouraging for using tsunami magnetic signals in warning systems.

Description: We present a new computational method of automatic normal moveout (NMO) correction that not only accurately flattens and corrects the far offset data, but simultaneously provides NMO velocity ( \(v_\mathrm{nmo}\) ) for each individual seismic trace. The method is based on a predefined number of NMO velocity sweeps using linear vertical interpolation of different NMO velocities at each seismic trace. At each sweep, we measure the semblance between the zero offset trace (pilot trace) and the next seismic trace using a trace-by-trace rather than sample-by-sample based semblance measure; then after all the sweeps are done, the one with the maximum semblance value is chosen, which is assumed to be the most suitable NMO velocity trace that accurately flattens seismic reflection events. Other traces follow the same process, and a final velocity field is then extracted. Isotropic, anisotropic and lateral heterogenous synthetic geological models were built to test the method. A range of synthetic background noise, ranging from 10 to 30 %, was applied to the models. In addition, the method was tested on Hess’s VTI (vertical transverse isotropy) model. Furthermore, we tested our method on a real pre-stack seismic CDP gathered from a gas field in Alaska. The results from the presented examples show an excellent NMO correction and extracted a reasonably accurate NMO velocity field.

Description: While the Intergovernmental Panel on Climate Change (IPCC) is continuously improving its communication, visualisation has taken a back seat to more pressing issues. The consequence is a set of IPCC imagery where our understanding of perception remains empirically unchallenged. The visual design (defined in this study as the method, technique, and style used to create a visual) directly affects perception and yet, we know very little about how people intuitively respond to visuals depicting climate science. This study examines the perception of four images from the IPCC summary report for policymakers and two open sourced infographics. Using a group-administered study we found the visual design to have a significant impact on a novice readers ability to associate relevant words with an image. While the visuals part of the summary for policymakers educed a sense of confidence, a well-designed infographic left readers feeling less confident. The veneer of legitimacy associated with IPCC visuals is because they look scientific, whereas infographic images were found to look less serious. We acknowledge the accessibility of an infographic but urge IPCC authors to use it with caution, as any negative impact on scientific credibility is an unwanted feature in IPCC communication.

Description: Freshwater ecosystems in many parts of the world have been severely affected by past management practices that have altered the volume, timing and quality of water flows and caused a decline in their ecological health. Some of these systems are also experiencing the negative impacts of climate change. Adaptation to climate change and the continual need to address existing ecological damage poses ongoing challenges for freshwater managers. In this paper we propose and discuss a Catchment Assessment Framework (CAF) that is used to evaluate existing and potential freshwater management actions, such as riparian revegetation and habitat connectivity, for their adaptation potential. The CAF was developed as a tool for prioritizing low risk climate change adaptation options in Australian catchment management. The CAF enables catchment managers and technical experts to assess management actions against seven inter-related criteria to provide a holistic assessment: relevance to the catchment; climate change adaptation potential, including potential for maladaptation and benefit under different climate scenarios; ecosystem service benefits; compatibility with other actions; implementation constraints; socio-economic consequences; and a risk assessment. It was developed and applied by assessing nine management options with stakeholders in three catchments within the Murray-Darling Basin in south-eastern Australia. We found that while management options are undertaken as a response to existing degradation, they can be used as building blocks for a climate change adaptation strategy that considers a range of different but complementary measures to better manage climate-related risk. The CAF enables practitioners to assess the advantages of a range of adaptation options and to subject them to their wider decision making and management planning.

Description: This paper compares projections over the twenty-first century of SO 2 , BC, and OC emissions from three technologically detailed, long-term integrated assessment models. The character of the projections and the response of emissions due to a comprehensive climate policy are discussed focusing on the sectoral level. In a continuation of historical experience, aerosol and precursor emissions are increasingly decoupled from carbon dioxide emissions over the twenty-first century due to a combination of emission controls and technology shifts over time. Implementation of a comprehensive climate policy further reduces emissions, although there is significant variation in this response by sector and by model: the response has many similarities between models for the energy transformation and transportation sectors, with more diversity in the response for the building and industrial sectors. Much of these differences can be traced to specific characteristics of reference case end-use and supply-side technology deployment and emissions control assumptions, which are detailed by sector.

Description: The approach in China since the last 1.5 decade for using apparent stress in time-dependent seismic hazard assessment or earthquake forecast is summarized. Retrospective case studies observe that apparent stress exhibits short-term increase, with time scale of several months, before moderate to strong earthquakes in a large area surrounding the ‘target earthquake’. Apparent stress is also used to estimate the tendency of aftershock activity. The concept relating apparent stress indirectly to stress level is used to understand the properties of some ‘precursory’ anomalies. Meanwhile, different opinions were reported. Problems in the calculation also existed for some cases. Moreover, retrospective studies have the limitation in their significance as compared to forward forecast test. Nevertheless, this approach, seemingly uniquely carried out in a large scale in mainland China, provides the earthquake catalogs for the predictive analysis of seismicity with an additional degree of freedom, deserving a systematic review and reflection.

Description: Household flood management measures can significantly reduce the risk from flooding. Understanding the factors that influence the uptake of measures has important implications for the design of measures to induce people to take charge of risk mitigation. We investigate the impact of flood action groups in communities in Scotland on the uptake of four measures: insurance, flood warnings, sandbags and floodgates applying regression analysis using a cross-sectional survey ( n  = 124). The groups were formed in response to the threat from flooding in those communities, and offer information and training on household flood management measures. We use the theoretical framework of Protection Motivation Theory, and compare uptake of the measures before and after the foundation of the flood action groups, as well as in the near future. The models show positive adoption effects for flood warnings, floodgates and to an extent for insurance, and a positive correlation with increased confidence of implementing and belief in the effectiveness of the measures. The effect is significant if specific information on the measures was provided, indicating the importance of tailored content. We conclude that appropriately designed flood action groups can be a cost-effective way of increasing the uptake of household flood management measures.

Description: Research reveals that liberals and conservatives in the United States diverge about their beliefs regarding climate change. We show empirically that political affiliation also matters with respect to climate related risks such as flooding from hurricanes. Our study is based on a survey conducted 6 months after Superstorm Sandy in 2012 of over 1,000 residents in flood-prone areas in New York City. Democrats’ perception of their probability of suffering flood damage is significantly higher than Republicans’ and they are also more likely to invest in individual flood protection measures. However, 50% more Democrats than Republicans in our sample expect to receive federal disaster relief after a major flood. These results highlight the importance of taking into account value-based considerations in designing disaster risk management policies.

Description: A 2030 climate and energy policy framework was endorsed by the European Council in 2014. The main elements are a binding 40 % greenhouse gas (GHG) reduction target compared to 1990, a renewable energy share of 27 %, and an energy savings target of at least 27 % by 2030. In this paper, we assess the impact of these targets on the European land use, land use change, and forestry (LULUCF) sector using a Europe focused global land use model linked with a detailed forest management model. We show that implementing a 40 % GHG emission reduction target by 2030 may only have a small negative impact on the domestic LULUCF sink if the additional biomass demand for energy is mostly met through ligno-cellulosic energy crops rather than forest removals. However, if the increased biomass demand were met through higher rates of forest harvest removals, a more negative impact on the LULUCF sink could be expected.

Description: Transboundary river basins face significant threats from climate change, with the need for adaptation widely noted. In this paper we develop a theoretically-rooted indicator-based evaluation framework to identify transboundary river basins where the need for adaptation support is pronounced and prioritize where attention is best placed. The framework combines indicators which capture the broad level potential to adapt (adaptive capacity) and the actual preparedness for adaptation (adaptation readiness) at the level of transboundary institutions. Adaptive capacity and adaptation readiness have not previously been evaluated and compared within a single framework, and by combining them we gain a more comprehensive and nuanced basis for characterising and evaluating the adaptation landscape and diagnosing opportunities and constraints for adaptation. We apply the framework to 42 transboundary basins in Mediterranean Europe, the Middle East, North Africa and sub-Saharan Africa, which account for 15 % of global transboundary river basins, are home to over 550 million people, and cover 8 % of Earth’s total land area. We find: 1) There is widespread need for improving national and transboundary institutional support for adaptation spanning basins of various economic, physical, and demographic characteristics; 2) Many transboundary basins in Africa have low adaptive capacity, but were found to have high readiness to begin adapting if resources were available; and 3) Improved coverage of River Basin Organisations and treaties with mandates to recognise and respond actively to climate change would underpin adaptation efforts across basins.

Description: By 15 December 2015, 187 countries had submitted their Intended Nationally Determined Contributions (INDCs) summarising their climate actions after 2020 in the context of the Paris Agreement. We used a unified framework to assess the mitigation components of INDCs covering 105 countries (representing approximately 91 % of global greenhouse gas emissions in 2012) with a special focus on the G20 economies. We estimated the required reduction effort by comparing the greenhouse gas emission targets implied by the INDCs with the projected levels resulting from current mitigation policies. The resulting projected global reduction effort amounts to approximately 4–6 GtCO 2 eq by 2030, of which the G20 economies are responsible for the largest share, in particular Brazil, China, the EU, and the United States. Despite these reductions, the global and G20 emission level is still projected to be higher in 2030 than it was in 2010. We compared the ambition levels of individual INDCs by analysing various indicators. Our analysis shows, for instance, that INDCs imply that greenhouse gas emissions of Brazil, Indonesia, Mexico, and South Korea peak before 2025, and of China, India and South Africa by 2030 or later.

Description: We evaluate the applicability and the effectiveness of texture attribute analysis of 2-D and 3-D GPR datasets obtained in different archaeological environments. Textural attributes are successfully used in seismic stratigraphic studies for hydrocarbon exploration to improve the interpretation of complex subsurface structures. We use a gray-level co-occurrence matrix (GLCM) algorithm to compute second-order statistical measures of textural characteristics, such as contrast, energy, entropy, and homogeneity. Textural attributes provide specific information about the data, and can highlight characteristics as uniformity or complexity, which complement the interpretation of amplitude data and integrate the features extracted from conventional attributes. The results from three archaeological case studies demonstrate that the proposed texture analysis can enhance understanding of GPR data by providing clearer images of distribution, volume, and shape of potential archaeological targets and related stratigraphic units, particularly in combination with the conventional GPR attributes. Such strategy improves the interpretability of GPR data, and can be very helpful for archaeological excavation planning and, more generally, for buried cultural heritage assessment.

Description: The 2011 Tohoku tsunami entered the Kitakami river and propagated there as a train of shock waves, recorded with a 1-min interval at water level stations at Fukuchi, Iino, and the weir 17.2 km from the mouth, where the bulk of the wave was reflected back. The records showed that each bore kept its shape and identity as it traveled a 10.9-km-path Fukuchi–Iino–weir–Iino. Shock handling based on the cross-river integrated classical shock conditions was applied to reconstruct the flow velocity time histories at the measurement sites, to estimate inflow into the river at each site, to evaluate the wave heights of incident and reflected tsunami bores near the weir, and to estimate propagation speed of the individual bores. Theoretical predictions are verified against the measurements. We discuss experiences of exercising the shock conditions with actual tsunami measurements in the Kitakami river, and test applicability of the shallow-water approximation for describing tsunami bores with heights ranging from 0.3 to 4 m in a river segment with a depth of 3–4 m.

Description: Large-scale data from digital infrastructure, like mobile phone networks, provides rich information on the behavior of millions of people in areas affected by climate stress. Using anonymized data on mobility and calling behavior from 5.1 million Grameenphone users in Barisal Division and Chittagong District, Bangladesh, we investigate the effect of Cyclone Mahasen, which struck Barisal and Chittagong in May 2013. We characterize spatiotemporal patterns and anomalies in calling frequency, mobile recharges, and population movements before, during and after the cyclone. While it was originally anticipated that the analysis might detect mass evacuations and displacement from coastal areas in the weeks following the storm, no evidence was found to suggest any permanent changes in population distributions. We detect anomalous patterns of mobility both around the time of early warning messages and the storm’s landfall, showing where and when mobility occurred as well as its characteristics. We find that anomalous patterns of mobility and calling frequency correlate with rainfall intensity ( r  = .75, p  〈 0.05) and use calling frequency to construct a spatiotemporal distribution of cyclone impact as the storm moves across the affected region. Likewise, from mobile recharge purchases we show the spatiotemporal patterns in people’s preparation for the storm in vulnerable areas. In addition to demonstrating how anomaly detection can be useful for modeling human adaptation to climate extremes, we also identify several promising avenues for future improvement of disaster planning and response activities.

Description: This paper analyses the response of alcohol thermometers in relation to the departure from linearity and the choice of the calibration points. The result is that alcohol thermometers are affected by large departures that reach a maximum (i.e. −6 °C) at 50 °C ambient temperature. This may have caused a severe bias in early records, when alcohol thermometers were popular, especially during the Little Ice Age. Choosing a lower temperature for the upper point, calibration may substantially reduce this bias. Examples are given with thermometers in use in the 17th and 18th centuries. A careful correction of long series is necessary to avoid misleading climate interpretations.

Description: Crustal earthquake focal mechanisms are investigated in the southeastern margin of the Tibetan Plateau, where the Tibetan Plateau and stable South China Block merge. An updated database of focal mechanisms has been compiled by selecting 132 Global Centroid Moment Tensor solutions and by adding the 173 new solutions (3.5 ≤  M s ≤ 7.4) estimated by waveform inversion in this study. A total of 305 mechanisms are included in this database. These solutions show regionally specific distributions with dominant strike-slip faulting and some normal and reverse faulting. Focal mechanism solutions have also been inverted for the stress tensor orientation to obtain the principal stress axes over the study region. Results show that the horizontal maximum principal σ 1 axes rotate clockwise with a wider range than the geodetically measured surface motion in the east, which is not limited to the Xianshuihe–Xiaojiang fault, but has some overlap with the Zhaotong–Lianfeng fault. Localized normal faulting stress regimes are observed in the Jinshajiang–Litang fault areas and the Baoshan sub-block. The minimum principal axes are oriented with a gradually changing trend from north–south to northwest–southeast, from north to south, indicating diverse compression stress patterns. Significant changes in the crustal stress field after the Wenchuan earthquake are preliminarily observed in the Baoshan sub-block where orientations of two principal axes have changed, and in the Jinggu–Ximeng sub-block areas where the strike-slip faulting stress pattern has transformed to normal faulting.

Description: Recently, coda-wave interferometry has been used to monitor temporal changes in subsurface structures. Seismic velocity changes have been detected by coda-wave interferometry in association with large earthquakes and volcanic eruptions. To constrain the spatial extent of the velocity changes, spatial homogeneity is often assumed. However, it is important to locate the region of the velocity changes correctly to understand physical mechanisms causing them. In this paper, we are concerned with the sensitivity kernels relating travel times of coda waves to velocity changes. In previous studies, sensitivity kernels have been formulated for two-dimensional single scattering and multiple scattering, three-dimensional multiple scattering, and diffusion. In this paper, we formulate and derive analytical expressions of the sensitivity kernels for three-dimensional single-scattering case. These sensitivity kernels show two peaks at both source and receiver locations, which is similar to the previous studies using different scattering models. The two peaks are more pronounced for later lapse time. We validate our formulation by comparing it with finite-difference simulations of acoustic wave propagation. Our formulation enables us to evaluate the sensitivity kernels analytically, which is particularly useful for the analysis of body waves from deeper earthquakes.

Description: Cirrus clouds reflect incoming solar radiation, creating a cooling effect. At the same time, these clouds absorb the infrared radiation from the Earth, creating a greenhouse effect. The net effect, crucial for radiative transfer, depends on the cirrus microphysical properties, such as particle size distributions and particle shapes. Knowledge of these cloud properties is also needed for calibrating and validating passive and active remote sensors. Ice particles of sizes below 100 µm are inherently difficult to measure with aircraft-mounted probes due to issues with resolution, sizing, and size-dependent sampling volume. Furthermore, artefacts are produced by shattering of particles on the leading surfaces of the aircraft probes when particles several hundred microns or larger are present. Here, we report on a series of balloon-borne in situ measurements that were carried out at a high-latitude location, Kiruna in northern Sweden (68N 21E). The method used here avoids these issues experienced with the aircraft probes. Furthermore, with a balloon-borne instrument, data are collected as vertical profiles, more useful for calibrating or evaluating remote sensing measurements than data collected along horizontal traverses. Particles are collected on an oil-coated film at a sampling speed given directly by the ascending rate of the balloon, 4 m s −1 . The collecting film is advanced uniformly inside the instrument so that an always unused section of the film is exposed to ice particles, which are measured by imaging shortly after sampling. The high optical resolution of about 4 µm together with a pixel resolution of 1.65 µm allows particle detection at sizes of 10 µm and larger. For particles that are 20 µm (12 pixel) in size or larger, the shape can be recognized. The sampling volume, 130 cm 3  s −1 , is well defined and independent of particle size. With the encountered number concentrations of between 4 and 400 L −1 , this required about 90- to 4-s sampling times to determine particle size distributions of cloud layers. Depending on how ice particles vary through the cloud, several layers per cloud with relatively uniform properties have been analysed. Preliminary results of the balloon campaign, targeting upper tropospheric, cold cirrus clouds, are presented here. Ice particles in these clouds were predominantly very small, with a median size of measured particles of around 50 µm and about 80 % of all particles below 100 µm in size. The properties of the particle size distributions at temperatures between −36 and −67 °C have been studied, as well as particle areas, extinction coefficients, and their shapes (area ratios). Gamma and log-normal distribution functions could be fitted to all measured particle size distributions achieving very good correlation with coefficients R of up to 0.95. Each distribution features one distinct mode. With decreasing temperature, the mode diameter decreases exponentially, whereas the total number concentration increases by two orders of magnitude with decreasing temperature in the same range. The high concentrations at cold temperatures also caused larger extinction coefficients, directly determined from cross-sectional areas of single ice particles, than at warmer temperatures. The mass of particles has been estimated from area and size. Ice water content (IWC) and effective diameters are then determined from the data. IWC did vary only between 1 × 10 −3 and 5 × 10 −3  g m −3 at temperatures below −40 °C and did not show a clear temperature trend. These measurements are part of an ongoing study.

Description: Different waveform-based discrimination parameters were tested using multivariate statistical analysis to develop a real-time procedure for discriminating explosions from earthquakes at regional distances in the Iberian Peninsula. This work enabled a purge of the Spanish National Seismic Catalogue for the period 2003–2014. The training data consisted of waveform-based signal properties in the time and frequency domain for events (earthquakes and explosions) recorded during the selected time period by the Spanish Broadband National Network and Sonseca short-period Array of the Instituto Geográfico Nacional (IGN). For each station and its associated training dataset, a discriminant function was defined as a linear combination of the measured variables. All station-specific discriminant functions were then combined with a weighting scheme to test the training events, revealing that 86 % of the events were consistent with the analysts’ judgement. The application of this method to the whole of the IGN’s seismic database for the studied period gave an 83 % success rate; however, a 91 % success rate is reached if events are classified using at least three stations and 100 % confidence levels.

Description: We investigated the effect that along-dip slip distribution has on the near-shore tsunami amplitudes and on coastal land-level changes in the region of central Chile (29°–37°S). Here and all along the Chilean megathrust, the seismogenic zone extends beneath dry land, and thus, tsunami generation and propagation is limited to its seaward portion, where the sensitivity of the initial tsunami waveform to dislocation model inputs, such as slip distribution, is greater. We considered four distributions of earthquake slip in the dip direction, including a spatially uniform slip source and three others with typical bell-shaped slip patterns that differ in the depth range of slip concentration. We found that a uniform slip scenario predicts much lower tsunami amplitudes and generally less coastal subsidence than scenarios that assume bell-shaped distributions of slip. Although the finding that uniform slip scenarios underestimate tsunami amplitudes is not new, it has been largely ignored for tsunami hazard assessment in Chile. Our simulations results also suggest that uniform slip scenarios tend to predict later arrival times of the leading wave than bell-shaped sources. The time occurrence of the largest wave at a specific site is also dependent on how the slip is distributed in the dip direction; however, other factors, such as local bathymetric configurations and standing edge waves, are also expected to play a role. Arrival time differences are especially critical in Chile, where tsunamis arrive earlier than elsewhere. We believe that the results of this study will be useful to both public and private organizations for mapping tsunami hazard in coastal areas along the Chilean coast, and, therefore, help reduce the risk of loss and damage caused by future tsunamis.

Description: The consecutive summer monsoons of 2013 and 2014 over the Indian subcontinent saw very contrasting onsets and progressions during the initial month. While the 2013 monsoon saw the timely onset and one of the fastest progressions during the recent decades, 2014 had a delayed onset and a slower progression phase. The monthly rainfall of June 2013 was +34 %, whereas in 2014 it was −43 % of its long-period average. The progress/onset of monsoon in June is influenced by large-scale circulation and local feedback processes. But, in 2013 (2014), one of the main reasons for the timely onset and fastest progression (delayed onset and slower progression) was the persistent strong (weak) convection over the north equatorial Indian Ocean during May. This resulted in a strong (weak) Hadley circulation with strong (weak) ascent and descent over the north equatorial Indian Ocean and the South Indian Ocean, respectively. The strong (weak) descent over the south Indian Ocean intensified (weakened) the Mascarene High, which in turn strengthened (weakened) the cross-equatorial flow and hence the monsoonal circulation.

Description: The stochastic Truncated Lévy Flight model and detrended fluctuation analysis (DFA) are used to investigate the temporal distribution of earthquake magnitudes in Chile. We show that Lévy Flight is appropriated for modeling the time series of the magnitudes of the earthquakes. Furthermore, DFA shows that these events present memory effects, suggesting that the magnitude of impeding earthquakes depends on the magnitude of previous earthquakes. Based on this dependency, we use a non-linear regression to estimate the magnitude of the 2015, M8.3 Illapel earthquake based on the magnitudes of the previous events.

Description: We studied 62 normal-faulting inslab earthquakes in the Mexican subduction zone with magnitudes in the range of 3.6 ≤  M w  ≤ 7.3 and hypocentral depths of 30 ≤  Z  ≤ 108 km. We used different methods to estimate source parameters to observe differences in stress drop, corner frequencies, source dimensions, source duration, energy-to-moment ratio, radiated efficiency, and radiated seismic energy. The behavior of these parameters is derived. We found that normal-faulting inslab events have higher radiated seismic energy, energy-to-moment ratio, and stress drop than interplate earthquakes as expected. This may be explained by the mechanism dependence of radiated seismic energy and apparent stress reported in previous source parameter studies. The energy-to-moment ratio data showed large scatter and no trend with seismic moment. The stress drop showed no trend with seismic moment, but an increment with depth. The radiated seismic efficiencies showed similar values to those obtained from interplate events, but higher than near-trench events. We found that the source duration is independent of the depth. We also derived source scaling relationships for the mentioned parameters. The low level of uncertainties for the seismic source parameters and scaling relationships showed that the obtained parameters are robust. Therefore, reliable source parameter estimation can be carried out using the obtained scaling relationships. We also studied regional stress field of normal-faulting inslab events. Heterogeneity exists in the regional stress field, as indicated by individual stress tensor inversions conducted for two different depth intervals ( Z  〈 40 km and Z  〉 40 km, respectively). While the maximum stress axis ( σ 1 ) appears to be consistent and stable, the orientations of the intermediate and minimum stresses ( σ 2 and σ 3 ) vary over the depth intervals. The stress inversion results showed that the tensional axes are parallel to the dip direction of the subducted plate. At depths greater than 40 km, the maximum horizontal stresses are oblique to the dip direction following the general trend of the slab geometry.

Description: During the TSUJAL marine geophysical survey, conducted in February and March 2014, Spanish, Mexican and British scientists and technicians explored the western margin of Mexico, considered one of the most active seismic zones in America. This work aims to characterize the internal structure of the subduction zone of the Rivera plate beneath the North American plate in the offshore part of the Jalisco Block, to link the geodynamic and the recent tectonic deformation occurring there with the possible generation of tsunamis and earthquakes. For this purpose, it has been carried out acquisition, processing and geological interpretation of a multichannel seismic reflection profile running perpendicular to the margin. Crustal images show an oceanic domain, dominated by subduction–accretion along the lower slope of the margin with a subparallel sediment thickness of up to 1.6 s two-way travel time (approx. 2 km) in the Middle American Trench. Further, from these data the region appears to be prone to giant earthquake production. The top of the oceanic crust (intraplate reflector) is very well imaged. It is almost continuous along the profile with a gentle dip (〈10°); however, it is disrupted by normal faulting resulting from the bending of the plate during subduction. The continental crust presents a well-developed accretionary prism consisting of highly deformed sediments with prominent slumping towards the trench that may be the result of past tsunamis. Also, a bottom simulating reflector (BSR) is identified in the first half a second (twtt) of the section. High amplitude reflections at around 7–8 s twtt clearly image a discontinuous Moho, defining a very gentle dipping subduction plane.