Geology topics

V.H. Garduño-Monroy

Publications and source records attributed to V.H. Garduño-Monroy.

3 recordsLinked to original sources

USGS2013

Roman, Visigothic and Islamic evidence of earthquakes recorded in the archaeological site of “El Tolmo de Minateda” (Prebetic Zone, southeast of Spain)

The archaeological site of “El Tolmo de Minateda” is located within the Albacete province (SE of Spain) and shows a continuous time record of ancient civilizations from 3500 yr BP onwards. However, three temporal gaps were identified in this archaeological record, all of them in relationship with a sudden and unclear abandonment of the city (Centuries 1st, 7th and 9-10th). The Archaeological Earthquake Effects (EAEs) supports the possibility that moderate to strong earthquakes were the cause of such abandonments: oriented columns fallen, collapsed walls and arches, abandonment of irrigation systems and fresh-water supplies, crashed pottery, etc. Despite of the scarce of instrumental seismicity and a few historical chronicles, paleoseismic studies performed in the neighbouring zone (Tobarra) suggest the presence of closer seismic sources as faults (Pozohondo Fault) affecting Quaternary alluvial, lacustrine deposits and colluviums. In this work, we propose the possibility that three moderate earthquakes devastated the ancient Roman city of Ilunum (Century 1st AD), the Visigothic city of Elo (Century 7th AD) and the Islamic city of Madinat Iyih (Century 9th-10thAD), all of them the same place: “El Tolmo de Minateda”.

Cuaternario y Geomorfologia↗

USGS2012

Paleoseismic and geomorphologic evidence of recent tectonic activity of the Pozohondo Fault (Betic Cordillera, SE Spain)

Instrumental and historical seismicity in the Albacete province (External Prebetic Zone) has been scarcely recorded. However, major strike-slip faults showing NW-SE trending provide geomorphologic and paleoseismic evidence of recent tectonic activity (Late Pleistocene to Present). Moreover, these faults are consistently well oriented under the present stress tensor and therefore, they can trigger earthquakes of magnitude greater than M6, according to the lengths of surface ruptures and active segments recognized in fieldwork. Present landscape nearby the village of Hellin (SE of Albacete) is determined by the recent activity of the Pozohondo Fault (FPH), a NW-SE right-lateral fault with 90 km in length. In this study, we have calculated the Late Quaternary tectonic sliprate of the FPH from geomorphological, sedimentological, archaeoseimological, and paleoseismological approaches. All of these data suggest that the FPH runs with a minimum slip-rate of 0.1 mm/yr during the last 100 kyrs (Upper Pleistocene-Holocene). In addition, we have recognized the last two major paleoearthquakes associated to this fault. Magnitudes of these paleoearthquakes were gretarer than M6 and their recurrence intervals ranged from 6600 to 8600 yrs for the seismic cycle of FPH. The last earthquake was dated between the 1st and 6th centuries, though two earthquakes could be interpreted in this wide time interval, one at the FPH and other from a far field source. Results obtained here, suggest an increasing of the tectonic activity of the Pozohondo Fault during the last 10,000 yrs.

Pozohondo Fault↗

USGS2010

Palaeoenvironmental significance of diatom and vertebrate fossils from Late Cenozoic tectonic basins in west-central México: A review

Pronounced lacustrine sedimentation developed in west-central México during the late Miocene, between approximately 11 and 7 Ma. This was in response to tectonic extension associated with the initial emplacement of the late Miocene substrata of the Trans-Mexican Volcanic Belt. Climatic conditions in west-central México during this interval were relatively warm and humid based on the widespread distribution of interpreted lacustrine beds. Following a latest Miocene (8.0–5.4 Ma) stage of arid conditions and greatly reduced deposition of fine-grained lacustrine sediments, extensive, east–west oriented, relatively deep, perennial lakes ensued. They mark the early Pliocene (5.3–4.0 Ma). Lower Pliocene diatomites contain the same diatom species (e.g., Stephanodiscus carconensis and Tertiarius aff. baikalensis) found in rocks of this age in the western United States. The relatively warm and humid conditions that characterized this interval in central México coincide with a period of high-latitude warming, higher global sea level, and a reduction in size of the Antarctic Ice sheets. Because the Central American Seaway persisted until at least the latest Miocene, it might have acted to increase precipitation in central Mexico. This could have continued into the earliest Pliocene. Mexican Pliocene mammalian faunas also support a savanna setting with moist and warm conditions prevailing at the time. Shallow lakes and fluvial conditions dominate after 4.0 Ma, until the end of Pleistocene. A combination of reduced precipitation, due to general global cooling and drying, as well as volcanic and tectonic processes, are presumed to have been the cause for this mid-Pliocene reduction in lake size and extent in central México.

Chincua, Ixtlahuaca↗