A double seismic front and earthquake cycles along the coast of Oaxaca, Mexico

[No abstract available

A double seismic front and earthquake cycles along the coast of Oaxaca, Mexico

[No abstract available

Seismicity and stress in a tectonically complex region: The rivera fracture zone, the rivera-cocos boundary, and the southwestern jalisco block, mexico

Fault plane solutions for a group of 41 4:9 ? Mw ?8:0 earthquakes between November 1980 and May 2007, extracted from the Global Centroid Moment Tensor Project catalog, are used to investigate spatial and temporal variations of stress in the south part of the Jalisco block (JB). Using rigorous statistical tests we decide on the quality and variability of the earthquake mechanisms and with the use of stress tensor inversion and cumulative misfit analysis find, at the 95% confidence level or more, significantly different regions and periods of stress regime. We conclude that the region located near (105 W, 18.43 N) appears as a particularly diffuse zone affected by various stress styles and that the period following the great Mw 8.0 earthquake on 9 October 1995 appears as a short-lived change in stress induced by the great shock. An important difference in seismicity and stress between the southern and northern regions is highlighted by the regular occurrence of earthquakes south of the JB, in stark contrast with the scarcity of seismicity with Mw >4:9 north of 19.36 N, a region that is illuminated with microseismicity when local temporal or permanent deployments of seismographs are used, as noted by previous studies. Online Material: Supplementary description and figures on the cumulative misfit method and the detection of boundaries between regions of different stress

The great 1787 Mexican tsunami

Tsunamis have proven to represent a significant hazard around the globe and there is increased awareness about their occurrence. The Pacific coast in southern México is no exception, because there is firm evidence of the effects of past large tsunamis. Here we present results from computer-aided modeling of the March 28, 1787- "San Sixto" earthquake and tsunami, and focus on the regions of Acapulco, Corralero, Jamiltepec, and Tehuantepec, located along the Guerrero-Oaxaca coast. The theoretical waveforms suggest wave heights in excess of 4 m and 18 m at specific locations in Acapulco and Corralero, respectively, and wave heights of at least 2 m at locations in Jamiltepec and Tehuantepec. From our modeling results and based on historical documents and the topography of the area, we conclude that these wave heights would have been sufficient to cause inundations that in the case of Acapulco were restricted to several meters inland, but in other areas like Corralero reached at least 6 km inland. Our results are consistent with published and unpublished damage reports that attest to the hazards associated with great earthquakes and tsunamis along the subduction zone in Mexico © Springer Science+Business Media B.V. 2008

Study of seismic clusters at Bahía de Banderas Región, México

The coast in the state of Jalisco and south of Nayarit is located within a region of high seismic potential, increasing population, and tourism development. This motivated Civil Defense authorities of Jalisco and the Universidad de Guadalajara to launch in the year 2000 the assessment of the seismic risk of the region. This work focuses in the seismicity study of the area of Bahía de Banderas and northern coast of Jalisco, which is actually a seismic gap. We perform an analysis of available seismograms to characterize active crustal structures, their relationship to surface morphology, and possible extent of these structures into the bay shallow parts. The data consist of waveforms recorded during 2003 when the seismograph network spanned the region. Our method is based on the identification of seismic clusters or families using cross-correlation of waveforms, earthquake relocation and modeling of fault planes. From an initial data set of 404 located earthquakes, 96 earthquakes with ML < 3.6 are related to 17 potentially active continental structures. We present fault plane model for 11 structures. A subgroup of 7 structures is aligned parallel to the Middle America Trench, as a possible consequence of oblique subduction. The foci of the earthquakes were grouped into clusters corresponding to fault dimensions of hundred of meters, may be considered as asperities or barriers in tectonic structures with lengths between 10 and 30 km. These structures could generate shallow earthquakes with magnitudes between 5.0 and 6.0 and represent an additional seismic threat to the region

Seismicity at ceboruco volcano, Mexico

[No abstract available

Some insights about the activity of the Ceboruco Volcano (Nayarit, Mexico) from recent seismic low-frequency activity

The Ceboruco stratovolcano (2,280 m.a.s.l.) is located in Nayarit, Mexico, at the western end of the Mexican volcanic belt, near several population centers and by the side of a strategic highway. During the last 1,000 years it has had, on the average, one eruption every 125 years. It last eruptive activity began in 1870, and during the following 5 years it presented superficial activity including vapor emissions, ash falls, and rhyodacitic lava flows along the southeast side. A data set consisting of 139 low-frequency volcanic-type earthquakes, recorded from March 2003 to July 2008 at the CEBN triaxial short period digital station on the southwestern side of the volcano, was classified according to waveform and spectral characteristics into four families: short duration, extended coda, bobbin, and modulated amplitude. Approximate hypocentral locations indicate that there is no particular location for events of any family, but rather that all events occur at different points within the volcano. The presence of ongoing volcanic-earthquake activity together with the ongoing vapor emissions indicate that the Ceboruco volcano continues to be active, and the higher occurrence rates of short-duration events, as compared with those for the other families, could indicate an increase in the stress in the volcanic edifice. This apparent stress increase, together with the fact that the last eruption occurred 143 years ago, tell us that the Ceboruco may be approaching a critical state, and may represent a hazard to the surrounding communities and economic activities. © 2013 Springer-Verlag Berlin Heidelberg

Erosion event at Mismaloya Beach, Jalisco, México [El evento erosivo de la playa de Mismaloya, Jalisco, México]

A study was carried out to determine the causes of the sudden disappearance of Mismaloya Beach, Jalisco (Mexico), in the early hours of 8 September 2001. This event occurred in a few hours, leaving behind a 2-m-high beach scarp as well as restaurants and palapas flooded by the ocean. Bathymetric and beach profiles were done to know the morphology and evolution of the coastal zone, and the bathymetry and eroded sediment volumes were obtained. Analyses were made of the coastal profile slopes, the physical characteristics of the sediments and the zone hydrodynamics. The event was caused by a slump of the sediments that lay over very steep slopes of the coastal profile (up to 18 ), as a consequence of the weight and tixotrophic properties of the sediments

Spatial structure of the spider crab, Maja brachydactyla population: Evidence of metapopulation structure

The Ceboruco stratovolcano (2,280 m.a.s.l.) is located in Nayarit, Mexico, at the western end of the Mexican volcanic belt, near several population centers and by the side of a strategic highway. During the last 1,000 years it has had, on the average, one eruption every 125 years. It last eruptive activity began in 1870, and during the following 5 years it presented superficial activity including vapor emissions, ash falls, and rhyodacitic lava flows along the southeast side. A data set consisting of 139 low-frequency volcanic-type earthquakes, recorded from March 2003 to July 2008 at the CEBN triaxial short period digital station on the southwestern side of the volcano, was classified according to waveform and spectral characteristics into four families: short duration, extended coda, bobbin, and modulated amplitude. Approximate hypocentral locations indicate that there is no particular location for events of any family, but rather that all events occur at different points within the volcano. The presence of ongoing volcanic-earthquake activity together with the ongoing vapor emissions indicate that the Ceboruco volcano continues to be active, and the higher occurrence rates of short-duration events, as compared with those for the other families, could indicate an increase in the stress in the volcanic edifice. This apparent stress increase, together with the fact that the last eruption occurred 143 years ago, tell us that the Ceboruco may be approaching a critical state, and may represent a hazard to the surrounding communities and economic activities. " 2013 Springer-Verlag Berlin Heidelberg.",,,,,,"10.1007/s00445-013-0755-9",,,"http://hdl.handle.net/20.500.12104/44648","http://www.scopus.com/inward/record.url?eid=2-s2.0-84883609943&partnerID=40&md5=36690c1c607bb363a2400bac84931036",,,,,,"10",,"Bulletin of Volcanology",,"

Erosion event at Mismaloya Beach, Jalisco, México [El evento erosivo de la playa de Mismaloya, Jalisco, México]

A study was carried out to determine the causes of the sudden disappearance of Mismaloya Beach, Jalisco (Mexico), in the early hours of 8 September 2001. This event occurred in a few hours, leaving behind a 2-m-high beach scarp as well as restaurants and palapas flooded by the ocean. Bathymetric and beach profiles were done to know the morphology and evolution of the coastal zone, and the bathymetry and eroded sediment volumes were obtained. Analyses were made of the coastal profile slopes, the physical characteristics of the sediments and the zone hydrodynamics. The event was caused by a slump of the sediments that lay over very steep slopes of the coastal profile (up to 18°), as a consequence of the weight and tixotrophic properties of the sediments