Física de la Tierra (ISSN: 0214-4557, ISSN-e 1988-2440) is an annual journal founded in 1989. It includes works on Geophysics, Geodesics, Meteorology and Oceanography in Spanish, Portuguese, French and English. Each issue focusses on a specific topic and presents the latest research. The indices and summaries of the articles published in the journal are compiled in Bibliografía Española de Revistas Científicas de Ciencia y Tecnología.
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The largest earthquakes in Algeria in the modern period: the El Asnam and Zemmouri-Boumerdès faults
Algeria has experienced many destructive earthquakes during the last few centuries (e.g., Ayadi and Bezzeghoud, 2015). The city of El Asnam (formerly Orléanville, today Chlef) was severely damaged in 1954 and 1980 by magnitude 6.7 and 7.3 earthquakes, respectively. On October 10, 1989, a magnitude 5.9 earthquake struck the Mont Chenoua-Tipasa coastal area approximately 150 km west of Zemmouri, which is where the May 21, 2003 earthquake occurred (Mw6.8). Many other large historical and instrumental earthquakes have severely damaged the coastal cities of Algeria over the last few centuries (i.e., around Algiers, Oran, Mascara, Djidjelli, Constantine and Bejaia). These earthquakes suggest active deformation of the margin in conjunction with the clear offshore extent of active coastal faults. According to several studies, the main active geological structures around El Asnam, Algiers, Zemmouri and Boumerdès have experienced several disastrous earthquakes. Many other earthquakes have occurred in and around the Chlef and Mitidja Basins, underlining the seismic activity in the area. In this chapter, we highlight the main characteristics of the two largest earthquakes that have occurred in Algeria in the modern period: the El Asnam earthquakes of September 9 (Mw6.7) and October 10 1980 (Mw7.3), and the Zemmouri-Boumerdès earthquake of May 21, 2003, (Mw6.8).
The large Algerian earthquakes (267 A.D.-2017)
In northern Algeria, large earthquakes occurred in the past as the El Asnam earthquake of October 10th, 1980 (Ms:7.3), one of the strongest event ever recorded in the western Mediterranean region. There were located mostly in the Tellian Atlas, some of them off the coastline as the Algiers (1365), Oran (1790), Djidjelli (1856) earthquakes or the last Boumerdes earthquake (2003). On land, no strong earthquakes have been recorded in the High plateaus or along the Saharan Atlas. From a synthesis of seismological or geodynamical studies carried out on the Algerian seismicity, we conclude that these main events along the African-Eurasiatic plate boundary are representative of the actual deformation pattern of the different geological domains of northern Algeria. They are generated mainly by reverse faults or strike slip faults in relation with the NW-SE to NNW-SSE stress regime (σ 1 striking N330°- N350°) inherited from the oblique convergence process between the two main plates in the western Mediterranean region. They are in general superficial located in the upper part of the crust (no more than 20 Km). Important earthquakes do not occur very often in Algeria in comparison with other seismic regions of the world. Their return period are estimated in some regions to be of many hundred of years. Large earthquakes still cause important damage to cities and villages, sometimes with the loss of thousand of citizens.
Re-examination of the historical 11 May, 1624 Fez earthquake parameters
The 11 May 1624 Fez earthquake is one of the worst natural disasters in the history of Morocco, and caused serious damage in the city of Fez and its surroundings. It occurred in one of the most active seismic zones in the country, and in an area that is now densely populated. The 1624 earthquake occurred at a crucial time in the history of Morocco (decline of the Saadian dynasty and outbreak of internal wars) which explains the lack of sufficient information on the extensive devastation that resulted from the earthquake. We consulted several Moroccan and European sources, whenever possible first hand. A complete historical review of testimonies and journals of the time describing this particular earthquake has been carried out. Correlation these effects with the local geological setting and the most recent seismological data shows that the focal region of the 1624 Fez earthquake is likely to be located somewhere along the E—W trending Rides Prérifaines, the main frontal thrust of the Rif. An evaluation of the magnitude of the earthquake is proposed, on the basis of existing empirical relationships. Understanding this earthquake may improve the seismic hazard assessment of the region.
This work describes the most important earthquakes (I > VII) that took place in the area close to the Vega Baja of the Segura River. From new works related to the seismicity of the area and considering the known historical documents, an individual analysis of each earthquake in order to assign the parameters of location more accurately is carried out. A new assessment of the points of macroseismic intensity, allowing in some earthquakes to determine its size, either in terms of moment magnitude or maximum intensity, is also conducted.
Los terremotos de 1748 de Montesa (Valencia) y de 1790 de Orán (Argelia)
The Montesa (Valencia) earthquake of 23 March 1748 and the Orán (Algeria) earthquake of 9 October 1790 caused heavy damage and were felt over a wide area. The abundant contemporary documentation about the damage caused by these earthquakes, allows a re-evaluation of the seismic intensity distribution giving a maximum intensity I = IX (EMS-1998) for Montesa and IX-X for Oran. From intensities distribution it is possible to correlate the seismic ruptures with the geological faults in the epicentral area. For the Oran earthquake we propose an off-shore focus due to the occurrence of a tsunami. The Montesa and Oran earthquakes have occurred in a region considered of low seismic hazard where few large earthquakes have happened.
The Large Earthquakes of the XV Century in Catalonia. Clues for the Regional Seismic Hazard.
Catalonia, in the NE part of the Iberian Peninsula, was shaken by large earthquakes in the XV Century. As these are the largest events consigned in the regional catalogues of seismicity, a proper knowledge of their epicentral parameters and their effects is essential for any further analysis of regional seismic hazard and risk. We review the present knowledge of these important events and some applications of the obtained results for the calculation of scenarios and other products really useful for civil protection for present earthquakes.
The Lower Tagus Valley (Portugal) earthquakes: Lisbon 26 January 1531 and Benavente 23 April 1909
The Lower Tagus Valley (LTV) has been the source of several local earthquakes that affected the region of Lisbon, in the central part of Portugal. In spite of absence of strong earthquakes during the last 100 years, past events have produced large damage in this area. We present the state of the art concerning the last two major earthquakes, which occurred in 1531 and 1909. The effects of both events are described, based on coeval reports already interpreted by several authors. The source parameters determined by different authors are also presented. The characterization of the seismogenic potential of the LTV is very important to better estimate the seismic hazard and risk of the region of Lisbon and Tagus Valley.
The Lisbon Earthquake of November 1, 1755
The 1755 earthquake of November 1, also called the Lisbon Earthquake for being the main city that suffered its multiple effects: earthquake, tsunami and fire. However, the affected area was very extensive, could be estimated at ten million square kilometres. The movement of the soil caused much damage in large parts of Spain, Portugal and Morocco, resulting in significant economic and social costs. The earthquake, with marine epicenter, also generated a noticeable alteration of the sea whose waves swept the Atlantic coasts of the Peninsula and North Africa. Also, as with large earthquakes (8,5 Mw, Martínez Solares, 2001), most of the hydrogeological effects that can be produce in nature, from cracks in the field to liquefaction, also occurred.
The history of the Azores archipelago, from its discovery and settlement in the first half of the 15th century through the present, is marked by the social and economic impacts produced by earthquakes, mainly the high-intensity ones. Information that has been compiled leads to the conclusion that in this period, 33 earthquakes with intensity equal to or greater than VII have affected the Azores, which caused approximately 6,300 deaths and widespread destruction on some islands of the archipelago, principally S. Miguel, Terceira, Graciosa, Faial, S. Jorge and Pico Islands. The accommodation of strain resulting from the dynamics of the Azores triple junction (ATJ) plate boundary and volcanism, which also occurs in the region, are the main factors responsible for the intense seismic activity in this archipelago. This work reviews the scientific issues of the known earthquakes that have severely interfered with the lives of the Azorean people throughout their history, which we call large earthquakes.
Earthquakes in the Iberian Peninsula before 1900 in the seismic catalogs
In this work we study the catalogs where earthquakes of the Iberian Peninsula before 1900 are contained. The catalog by Moreira de Mendonça (1758) published after the Lisbon earthquake stands out among those published before 1800 with 45 events in the peninsula. The global catalogs after 1800 give a larger number corresponding to those of larger size. The catalog by Mallet and Mallet (1858) with 110 earthquakes in the peninsula is that with a larger number. A list is given of the 21 earthquakes considered to be the most important and which appeared in several catalogues. The first regional catalog for the Peninsula is that of Perrey (1847) with 220 earthquakes. In regional catalogs the number of earthquakes increases; that by Navarro-Neumann (1921) has 260 and the one by Galvis (1932) has 1200. Modern catalogs have been developed from these ones which add the quantification of location (epicenter) and size (intensity and magnitude). The most complete catalog is that by Martínez-Solares and Mezcua (2002) that contains 2417 earthquakes before 1900. The development of the catalogs is important in the study of seismicity and seismic risk.
Prólogo: Grandes terremotos en la región Ibero-Mogrebi
Una prueba de la técnica multi-espécimen para determinar paleointensidad utilizando material arqueomagnetico: resultados preliminares con arcillas quemadas Tunecinas
The multispecimen palaeointensity technique of Dekkers & Böhnel (2006) has been tested on archaeomagnetic material from five kilns from Tunisia. In a previous study all five kilns yielded good quality archaeointensities based on Thellier-type double heating experiments. Results obtained using the multispecimen technique compared well with the previously studied Thellier-type results, with a slight tendency towards lower values. Markedly lower values were observed in two kilns, results that were improved by increasing the proportion of the natural remanence remagnetised in the partial thermoremanence acquisition. One of the kilns showed a multicomponent remanence (due to partial heating) and gave relatively poor results.
MOURA magnetometer for Mars MetNet Precursor Mission. Its potential for an in situ magnetic environment and surface characterization
MOURA magnetometer and gradiometer is part of the scientific instrumentation for Mars MetNet Precursor mission. This work describes the objective of the investigation, summarizes the work done in the design and development of the sensor as well as its calibration, and shows the demonstration campaigns to show the potential of such instrument for planetary landers and rovers.
Chronogram of Solar Observations for the EXOMARS16 Solar Irradiance Sensor
ExoMars16 is the first mission of the ESA ExoMars programme. Its launch is planned for the Mars 2016 window and the arrival to Mars in October 2016. The mission consists of the Trace Gas Orbiter and an entry, descent and landing demonstrator module known as Schiaparelli. The latter is equipped with new testing technologies; including a Solar Irradiation Sensor (SIS) developed by the Instituto Nacional de Técnica Aeroespacial. SIS belongs to the DREAMS experiment to characterize the atmospheric environment of the Mars surface. SIS main goal is to measure the solar spectrum in Mars, the transparency of the atmosphere and the atmospheric dust content. Combined with the measurement of the electric fields from MicroAres, these measurements will allow to study the role of electric forces on dust lifting, the mechanism that initiates dust storms. The objective of this work is to characterize the visibility of the Sun from the Schiaparelli module and to establish a chronogram of solar observations for SIS. For this establishment the Sun position as seen from SIS has been calculated, determining the sunrises and sunsets times in UT. To obtain local coordinates, azimuth and elevation, a Montecarlo simulation of 1000 random positions within the ESA forecasted landing ellipse for Schiaparelli. Then, the most probable Sun visibility chronogram is determined, as well as the chronogram for the ellipse characteristic points that limit the error margins of this determination. This allows planning adequately the solar irradiation observations for SIS. The Sun will be visible for approximately 12 hours and 26 minutes each sol.
Biomimetic magnetite mediated by magnetosome proteins vs. ALH84001 meteorite magnetite: Are both comparable?
The suggestion in 1996 that the Martian meteorite ALH84001 could contain proof of possible biologic activity in the past have generated a huge controversy that last until today. One of the most discussed evidence is the presence of magnetite crystals that resemble those produced by a particular group of bacteria, the so called magnetotactic bacteria (MTB). These microorganisms are the only known example of biologically controlled biomineralization among the prokaryotes and exert an exquisite control over the biomineralization process of intracellular magnetite that result in crystals with very unique features that, so far, cannot be replicated by inorganic means. These unique features have been used to recognize the biological origin of natural terrestrial magnetites, but the problem arises when those same biogenecity criteria are applied to extraterrestrial magnetites. Most of the problems are caused by the fact that it is not clear whether or not some of those characteristics can be reproduced inorganically. Magnetosome protein mediated magnetite synthesis seems to be the best approach to obtain magnetosome-like magnetites, and such strategy may help clarify what is the specific biosignature of magnetotactic bacteria.
Solar cycle variations in the ionosphere of Mars
Solar cycle variations in solar radiation create notable changes in the Martian ionosphere, which have been analysed with Mars Express plasma datasets in this paper. In general, lower densities and temperatures of the ionosphere are found during the low solar activity phase, while higher densities and temperatures are found during the high solar activity phase. In this paper, we assess the degree of influence of the long term solar flux variations in the ionosphere of Mars.
Seasonal and interannual variability of solar radiation at Spirit, Opportunity and Curiosity landing sites
In this article we characterize the radiative environment at the landing sites of NASA's Mars Exploration Rover (MER) and Mars Science Laboratory (MSL) missions. We use opacity values obtained at the surface from direct imaging of the Sun and our radiative transfer model COMIMART to analyze the seasonal and interannual variability of the daily irradiation at the MER and MSL landing sites. In addition, we analyze the behavior of the direct and diffuse components of the solar radiation at these landing sites.
The revitalizing of Mars exploration in the early 1990s combined with the maturation of terrestrial mesoscale modeling codes provided fertile ground for the application of suitably modified models to the atmosphere of Mars. The use of mesoscale models, particular for Mars, has become an integral part of interpreting the data returned from missions and providing constraints and bounds on environmental conditions in support of mission planning and operations. Mesoscale models are ideal tools for greatly minimize risk during entry, descent, and landing phases. Slope winds, dust injection processes and atmospheric volatiles transport are the main Mars mesoscale circulations that affect the atmospheric structure and dynamics. In this article is also included as an example the meteorological simulation of Gale Crater environment, in which the Mars Science Laboratory (MSL) Rover Curiosity landed in August 2012, with the spanish weather station Rover Environmental Monitoring Station (REMS) aboard. The observational data record provides sufficient means against which to evaluate mesoscale model. Meteorological interpretations show a dynamically complex environment. Local, regional and synoptic scales all interact in nonlinear ways to produce the observed weather. Two different atmospheric periods could be distinguished inside the crater: semi-isolated period during most of the martian year (Ls 0, 90 and 180) and mixing period during the summer (Ls 270). During the semi-isolated period, warm air from south overrides the crater creating a very stable boundary layer. Crater air mass is generally much colder than outside the crater forcing downslope flows, thermodynamically driven, to not scour crater and hence decreasing mixing level in this period. Ls 270 was shown to be an anomalous season when air within and outside the crater was well mixed by strong, flushing, northerly flow and large amplitude breaking mountain waves. At other seasons, the air in the crater was more isolated form the surrounding environment.
Analysis of the environmental conditions at Gale Crater from MSL/REMS measurements
The environmental conditions at Gale Crater during the first 1160 sols of the Mars Science Laboratory (MSL) mission are assessed using measurements taken by the Rover Environmental Monitoring Station (REMS) on-board the MSL Curiosity rover. REMS is a suite of sensors developed to assess the environmental conditions along the rover traverse. In particular, REMS has been measuring atmospheric pressure, atmospheric and ground temperature, relative humidity, UV radiation flux and wind speed. Here we analyze processed data with the highest confidence possible of atmospheric pressure, atmospheric and ground temperature and relative humidity. In addition, we estimate the daily UV irradiation at the surface of Gale Crater using dust opacity values derived from the Mastcam instrument. REMS is still in operation, but it has already provided the most comprehensive coverage of surface environmental conditions recorded by a spacecraft landed on Mars.
Tim Berners Lee uses, for the first time, the HTTP protocol, the embryo of the world wide web (www). At the beginning of the century, the web evolved to web 2.0, which is based on the popularization of new electronic devices and user-friendly software. Its main paradigm is that the user of the www creates their own content and shares it with others in what has been called social media (forums, user communities, blog, social networks, etc). Scientists, technicians and anyone interested in Mars planet have found here the best place/way to express their opinions, listen and dialogue with other individuals, companies and institutions interested in this new challenge for the humanity.
Searching for brine on Mars using Raman spectroscopy
In the last few years, water ice and perchlorate salts capable of melting this ice and producing liquid solutions have been discovered at the surface and shallow subsurface of Mars. In addition to via melting of ice, perchlorate salts may also form liquid solutions by absorbing water vapor when the relative humidity is above a certain threshold in a process known as deliquescence. Formed either by melting or deliquescence, liquid solutions (brine) are the most likely way of liquid water activity on the Martian surface and in the shallow subsurface and are therefore important to understand the habitability of Mars. Using Raman spectroscopy, we provide reference spectra of various mixing states of liquid water, water ice and calcium perchlorate, all of which can occur during brine formation. We focus on the perchlorate symmetric stretching band and the O-H stretching vibrational band to distinguish brine from crystalline salt and water ice. We show that perchlorate brines can be identified by analyzing the peaks and their widths in the decomposed Raman spectra of the investigated samples. This serves as an important reference for future in-situ Raman spectrometers on Mars, such as those on the ExoMars and Mars 2020 rovers and can aid in the detection of brine formation on Mars.
On the surface of Mars several main aspects in combined form are conditioning the existence of life: temperature, humidity, pressure, composition of the atmosphere and radiation. The Earth also presents very dry and/or cold environments, which are close to Martian surface conditions with a high UV radiation. Due to the inability to test the survival capacity of extremely resistant organisms that live on these analog Mars environments, which are referred as extremophiles and extreme tolerant, climatic chambers that mimic the Mars climatology have been used. In this work we report the results obtained with the extreme tolerant lichen species Cicinaria gyrosa exposed at PASC (Planetary Atmospheric Surface Chamber, INTA, CAB) to Mars simulated parameters, that is, to a Mars atmospheric composition of mainly 95% of CO2 and a pressure of 7 mbar, to UV-solar radiation at Mars surface (>200 nm) and to a temperature of -93 ºC, in combined- and independent form, in order to obtain a deeper understanding of the individual and joint effects. The results obtained have demonstrated an extremely high resistance of this lichen species against Mars simulated environmental conditions.
Planetary Simulation Chambers bring Mars to laboratory studies
Although space missions provide fundamental and unique knowledge for planetary exploration, they are always costly and extremely time-consuming. Due to the obvious technical and economical limitations of in-situ planetary exploration, laboratory simulations are among the most feasible research options for making advances in planetary exploration. Therefore, laboratory simulations of planetary environments are a necessary and complementary option to expensive space missions. Simulation chambers are economical, more versatile, and allow for a higher number of experiments than space missions. Laboratory-based facilities are able to mimic the conditions found in the atmospheres and on the surfaces of a majority of planetary objects. Number of relevant applications in Mars planetary exploration will be described in order to provide an understanding about the potential and flexibility of planetary simulation chambers systems: mainly, stability and presence of certain minerals on Mars surface; and microorganisms potential habitability under planetary environmental conditions would be studied. Therefore, simulation chambers will be a promising tools and necessary platform to design future planetary space mission and to validate in-situ measurements from orbital or rover observations.
Performance of the Bulgarian WRF-CMAQ modelling system for three subdomains in Europe
The air quality modelling system WRF-CMAQ running at the National Institute of Meteorology and Hydrology (NIMH) in Sofia was applied to the European domain for the year 2010 in the frame of the Air Quality Model Evaluation International Initiative (AQMEII), Phase 2. The model system was set up for a domain of 5000x5000 km2 size with horizontal resolution of 25 km. The models’ options used and the emission input are briefly outlined. The model performance was investigated based on graphical plots and statistical indexes obtained by the web-based model evaluation platform ENSEMBLE. A preliminary operational model evaluation for ozone and particulate matter was conducted, comparing simulated and observed concentrations at ground level in three sub-domains of Europe. The analysis shows model overestimation for ozone and model underestimation for particulate matter. The best statistical indicators are for ozone concentrations during summer, when comparing data for EMEP stations in the EU domain. The worse results are for PM10 winter concentration in the region of the Balkan countries.
Use of CFD modeling for estimating spatial representativeness of urban air pollution monitoring sites and suitability of their locations
A methodology to estimate the spatial representativeness of air pollution monitoring sites is applied to two urban districts. This methodology is based on high resolution maps of air pollution computed by using Computational Fluid Dynamics (CFD) modelling tools. Traffic-emitted NO2 dispersion is simulated for several meteorological conditions taking into account the effect of the buildings on air flow and pollutant dispersion and using a steady state CFD-RANS approach. From these results, maps of average pollutant concentrations for January–May 2011 are computed as a combination of the simulated scenarios. Two urban districts of Madrid City were simulated. Spatial representativeness areas for 32 different sites within the same district (including the site of the operative air quality stations) have been estimated by computing the portion of the domains with average NO2 concentration differing less than a 20% of the concentration at each candidate monitoring site. New parameters such as the ratio AR between the representativeness area and the whole domain area or the representativeness index (IR) has been proposed to discuss and compare the representativeness areas. Significant differences between the spatial representativeness of the candidate sites of both studied districts have been found. The sites of the Escuelas Aguirre district have generally smaller representativeness areas than those of the Plaza de Castilla. More stations are needed to cover the Escuelas Aguirre district than for the Plaza de Castilla one. The operative air quality station of the Escuelas Aguirre district is less representative than the station of the Plaza de Castilla district. The cause of these differences seems to be the differences in urban structure of both districts prompting different ventilation.
High resolution air quality forecasts in the Western Mediterranean area within the MACC, MACC-II and MACC-III European projects
The European Earth observation programme Copernicus, formerly known as GMES (Global Monitoring for Environment and Security) is establishing a core global and regional environmental atmospheric service as a component of the Europe’s Copernicus/GMES initiative through successive R&D projects led by ECMWF (European Center for Medium-range Weather Forecasting) and funded by the 6th and 7th European Framework Programme for Research and Horizon 2020 Programme: GEMS, MACC, MACC-II and MACC-III. AEMET (Spanish State Meteorological Agency) has participated in the projects MACC and MACC-II and continues participating in MACC-III (http://atmosphere.copernicus.eu). AEMET has contributed to those projects by generating high-resolution (0.05 degrees) daily air-quality forecasts for the Western Mediterranean up to 48 hours aiming to analyse the dependence of the quality of forecasts on resolution. We monitor the evolution of different chemical species such as NO2, O3, CO y SO2 at surface and different vertical levels using the global model MOCAGE and the MACC Regional Ensemble forecasts as chemical boundary conditions. We will show different case-studies, where the considered chemical species present high values and will show a validation of the air-quality by comparing to some of the available air-quality observations (EMEP/GAW, regional -autonomous communities- and local -city councils- air-quality monitoring networks) over the forecast domain. The aim of our participation in these projects is helping to improve the understanding of the processes involved in the air-quality forecast in the Mediterranean where special factors such as highly populated areas together with an intense solar radiation make air-quality forecast-ing particularly challenging.
ARAMIS a regional air quality model for air pollution management: evaluation and validation
The aim of this research was to better understand the dynamics of air pollutants and to forecast the air quality over regional areas in order to develop emission abatement strategies for air pollution and adverse health effects. To accomplish this objective, we developed and applied a high resolution Eulerian system named ARAMIS (A Regional Air Quality Modelling Integrated System) over the north-east of Spain (Catalonia), where several pollutants exceed threshold values for the protection of human health. The results indicate that the model reproduced reasonably well observed concentrations, as statistical values fell within Environmental Protection Agency (EPA) recommendations and European (EU) regulations. Nevertheless, some hourly O3 exceedances in summer and hourly peaks of NO2 in winter were underestimated. Concerning PM10 concentrations less accurate model levels were obtained with a moderate trend towards underestimation during the day.
An on-line modelling study of the direct effect of atmospheric aerosols over Europe
Atmospheric aerosols affect human health, ecosystems, materials, visibility and Earth’s climate. Those effects are studied in this present work and depend mainly on the aerosol optical properties and how they influence the Earth’s radiation budget. Such properties can be divided on direct and semi-direct effect, produced by the scattering and absorption of radiation; and indirect effect, which influences the aerosols-cloud interactions. The aim of this work is to assess the direct effect through the study of the mean temperature; the radiation that reaches the Earth’s surface and at the top of the atmosphere; and the interaction of these meteorological variables with particulate matter (PM10). Results indicate decreases in temperature and radiation that reaches the Earth's surface, together with increases in the outgoing radiation at top of the atmosphere, and changes in the particulate matter, thus proving a colder climate due to the direct effect of atmospheric aerosols.