The August 20, 1852 earthquake in Santiago de Cuba

On August 20, 1852, an earthquake caused widespread destruction in the city of Santiago de Cuba and its surroundings. A comprehensive search for contemporary documentation was made. The information gathered was used for a detailed analysis of the damage from and characteristics of the earthquakes. Intensities were evaluated at 45 localities, and an isoseismal scheme has been drawn. Maximum intensity reached 8 degrees (MSK), and 6.4 was the estimated magnitude. Damage to the city of Santiago de Cuba has been studied in detail. The low quality of construction aggravated the damage. The total number of casualties was two dead and approximately 200 injured. The shock was felt within 80,000 km². The epicenter was determined as 19.75º N, 75.32º W, h = 30 km. This study shows that contemporary Cuban documents must be studied with care in their historical and cultural background to avoid overestimating earthquake intensities.     

Chemical residues in lime‐plastered archaeological floors

In addition to research carried out on soils and sediments, there is a parallel field of research applying the same analytical techniques to the study of chemical residues in stuccoes. The most common material used to build floors in Mesoamerica after the Classic period was lime plaster. The study of residues in stuccoes becomes, therefore, a very promising study area. In last 25 years the Archaeological Prospection Laboratory at Mexico's National Autonomous University has developed a research strategy to study human activities based on ethnoarchaeological studies to interpret the distribution of chemical residues in archaeological floors. The most successful applications have been in lime‐plastered surfaces; this article presents a brief review of these works. © 2007 Wiley Periodicals, Inc.     

Fault oneoff versus coseismic fluids reaction

The fault activation (fault on) interrupts the enduring fault locking (fault off) and marks the end of a seismic cycle in which the brittle-ductile transition (BDT) acts as a sort of switch. We suggest...     

Morphotectonic study of the Greater Antilles

The first morphotectonic model of the Greater Antilles is presented. The model is adjusted to the current dynamics between the Caribbean and North American plates. It is mainly elaborated by Rantsman’s methodology. We determined 2 megablocks, 7 macroblocks, 42 mesoblocks, 653 microblocks and 1264 nanoblocks. They constitute a set of active blocks under rotation, uplifting and tilting movements. A total of 11 active knots of faults and 8 cells are the main articulation areas. The largest seismogenetic structures in the Northern Caribbean are an array of the active fault segments. The majority of them are in the Caribbean-North American Plate Boundary Zone, the Hispaniola has the most complex neotectonic structure–associated with the central axis of the morphotectonic deformations in the region.     

Susceptibility to gravitational processes due to land cover change in the Río Chiquito-Barranca del Muerto subbasin(Pico De Orizaba Volcano,México)

Land cover change can lead to slope instability by accelerating erosive processes associated with agriculture, forestry, and infrastructure. The Rio Chiquito-Barranca del Muerto subbasin has experienced an increase in land cover change due to government programs and the establishment of agricultural and urban areas. The aim of this study was to provide a model to map the susceptibility to gravitational processes along sites where anthropogenic land cover change has occurred. The method was based on the stratification of the subbasin according to landforms and cartographic variables. These variables were used in a multi-criteria assessment to assign weights according to their contribution to the onset of new gravitational processes. Those weights were used to create a susceptibility map based on a weighted linear sum. The accuracy of the resulting map was validated in an error matrix with a random stratified design based on susceptibility classes per landform. The results produced a map of areas with susceptibility to gravitational processes due to land cover change; this susceptibility is very high in the undifferentiated pyroclastic slope and limestone mountain, where it derives not only from anthropogenic effects on natural vegetation cover, but also from steep slopes, weathered materials, low apparent density, high erosivity, and previous gravitational processes. The results support other studies that concluded that loss of vegetation is a triggering factor in the formation of gravitational processes, but also show that excessive reforestation can increase gravitational processes.