Person:
Llanes Estrada, María Pilar

First Name

María Pilar

Last Name

Llanes Estrada

URI

https://hdl.handle.net/20.500.14352/75225

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Geológicas

Department

Geodinámica, Estratigrafía y Paleontología

Area

Geodinámica Interna

Identifiers

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Now showing 1 - 8 of 8

Morphological and structural analysis in the Anaga offshore massif, Canary Islands: fractures and debris avalanches relationships
(Marine Geophysical Researches, 2003) Llanes Estrada, María Pilar; Muñoz, Araceli; Muñoz Martín, Alfonso; Acosta, Juan; Herranz Araújo, Pedro; Carbo Gorosabel, Andrés; Palomo, Carlos
As part of the ‘National Hydrographic and Oceanographic Research Plan for the Spanish Exclusive Economic Zone’, multibeam bathymetry and seismic reflection profiles were obtained in the Canary Islands aboard the R/V Hespérides. The submarine flanks of the Anaga offshore extension of Tenerife Island are here studied to analyze its geomorphology. In the north sector of the Anaga submarine massif, the extension of the Anaga Debris Avalanche has been mapped for the first time, and a volume of 36 km3 was calculated. The relationship between the Anaga and Orotava Debris Avalanches is also described. Faulting has been recognized as a key process for the occurrence of debris avalanches and the growth of volcanic lineaments. Moreover, faulting affects previous structures and the channelling of debris flows. Structural analysis shows the typical radial pattern of an oceanic island. In addition, a NE-SW dominant direction of faulting was obtained, consistent with the Tenerife Island structural trend seen in the Anaga Massif and Cordillera Dorsal. NW-SE and E-W are two other main trends seen in the area. Special interest is manifest in two long faults: ‘Santa Cruz Fault’ bounds the southern edge of Anaga offshore Massif with a length of 50 km and a direction that changes from NE-SW to almost E-W. The Güimar Debris Avalanche was probably channeled by this fault. The ‘Guayotá Fault’ was recognized in several seismic profiles with a N-S direction that changes towards NW-SE at its southern end. This fault affects the more recent sediments with a vertical offset of 25–30 m, along 60 km. It has been interpreted as a transpressive strike-slip fault.
Interactions between a transform fault and arc volcanism in the Bismarck Sea, Papua New Guinea
(Geochemistry, geophysics, geosystems, 2009) Llanes Estrada, María Pilar; Silver, E.; Day, S.; Hoffman, G.
We present a new interpretation of the geological evolution of the western branch of the Bismarck Sea Seismic Lineation (BSSL) region, offshore the northwestern coast of Papua New Guinea, from mapping and interpretation of bathymetry and backscatter data acquired aboard R/V Kilo Moana in 2004. At present, the Schouten Islands parallel the Papua New Guinea coast, but this distribution results from the left-lateral displacement of some of these volcanic islands by the Bismarck Sea Seismic Lineation. The trend of the islands and seamounts was initially aligned N-S and then displaced by the BSSL. Wei Island lies on a large submarine edifice that may have formed as part of a leaky transform. Subsequent to forming, Wei Island was bisected, and its pieces were displaced 45 km. Using this distance together with the strikeslip rate for the Bismarck Sea Seismic Lineation (predicted from the North Bismarck Plate-South Bismarck Plate pole), the division occurred approximately 385,000 years ago.
Modelización gravimétrica de la transición entre corteza continental y oceánica en el margen oeste de Galicia
(Geotemas, 2004) Druet Vélez, María; Muñoz Martín, Alfonso; Carbo Gorosabel, Andrés; Álvarez García, Juan; Llanes Estrada, María Pilar
Since 2001 marine gravity data have been collected on the North Atlantic Ocean around Galicia Mar,-,in. The aim of this paper is the analysis of the Bouguer anomaly map of the west margin of Galicia and the modelling of the ocean-continent boundary in this area. Very high Bouguer anomaly values have been obtained for this region, specially in the oceanic trust of the Iberian Abyssal Plain. A gravity low is related to the Galicia Bank continental block, and relative positive elongate highs correspond with the Peridotite Ridge and the Galicia Interior Basin. The two gravity models presented here, based on seismic refraction and reflection profiles, have allowed the characterization of the gravity limit between oceanic and continental trust in this margin. This limit is located 15 km eastwards in the northern profile 1, from the previous proposed limit based on sedimentary criteria.
Geological evolution of the volcanic island La Gomera, Canary Islands, from analysis of its geomorphology
(Marine geology, 2009) Llanes Estrada, María Pilar; Herrera, R.; Gómez, M.; Muñoz Martín, Alfonso; Acosta, Juan; Uchupi, E.; Smith, D.
Erosion and landslide processes played an important role in shaping the geomorphology of the Canary Islands. But for the heavily eroded La Gomera Island, those processes have been unclear. We conducted an integrated study of its offshore extension, onshore geology, and links between them in order to determine the geomorphological evolution of the island relative to the rest of the archipelago. The characteristics of the island's barrancos and its interfluves have led us to differentiate four types of morphological areas whose fluvial networks are in different stages of evolution. Those barrancos offshore are interrupted by La Gomera's shelf, and its erosion has been much greater than for the rest of the Canary Islands. Such erosion is both a function of time and varied swell action. La Gomera's insular slope is carved by a system of submarine canyons and channels that have morphology indicative of turbidity current erosion. Many of the barrancos onshore and the canyons offshore have steps or knickpoints: some are the result of varied resistance to erosion, and others are explained by other mechanisms. A ridge whose crest is covered by cone-like shape structures is interpreted as of volcanic origin, with the particularity that it lacks onshore continuation, the opposite of what has been observed elsewhere in the Canary Islands. Also in contrast with the other islands of the archipelago, La Gomera's margin does not seem to have resulted from destructive mass wasting and the only offshore sign of catastrophic events are the presence of two embayments along La Gomera's northern shelf edge and a lobe structure on the insular apron at 3000 m depth. These features may be the remains of the catastrophic failures that took place on the island 9.4-8.7 Ma ago. Alternatively, they could be due to recent catastrophic failures on the upper slope due to sediment steeping. Since the conclusion of the main volcanic activity 4.0 Ma ago, La Gomera has been intensively eroded by gradual fluvial denudation and secondary failures. La Gomera's insular margin reveals much regarding its evolution, but more comprehensive studies including seismic and coring are needed to understand its whole geological history.
New Gravity Map of the Western Galicia Margin:The Spanish Exclusive Economic Zone Project
(Eos, 2004) Carbo Gorosabel, Andrés; Muñoz Martín, Alfonso; Druet Vélez, María; Llanes Estrada, María Pilar; Álvarez García, Juan
Since 1995, the most intensive mapping of the seafloor off the Spanish coast has been carried out in the framework of the Spanish Exclusive Economic Zone Project (ZEEE).The main objectives of this project are to obtain improved multibeam bathymetric cartography of the areas off Spanish coastlines, and to perform a geophysical survey,well-suited with a 10-knot navigation velocity (some techniques requires lower navigation velocity). The geophysical survey includes gravity, geomagnetism, and low-penetration seismic techniques in order to infer the geological structure of the seafloor. Other oceanographic variables such as current, surface salinity, and temperature profiles, can be recorded without compromising this systematic survey effort. The ZEEE Project has carried out its survey activities for one month every year.Data acquisition is achieved aboard the Spanish R/V Hesperides. Until 1997, surveying efforts concentrated on the Balearic Sea and Valencia Gulf, both in the western Mediterranean Sea. Between 1998 and 2000, the ZEEE Project investigations were conducted offshore the Canary Archipelago. Since 2001, the third phase of the program has been focused on the West Galicia Margin in the northeastern Atlantic Ocean. Survey results on the West Galicia Margin area are of interest for two key reasons. First, there is great scientific interest in the improvement of the knowledge of this non-volcanic rifting margin, since this margin offers good conditions for the study of the processes that take place in this type of geological context,because it is sediment-starved. Second, the obtained results also have major socioeconomic repercussions because they can prove significant to defining the expansion of the Spanish shelf,beyond Spain’s Economic Exclusive Zone distance of 200 nautical miles. All of the gravity data acquired to date on this area have been stored as a database, with the aim of preparing gravity anomaly maps on a scale 1:200,000.The database and gravity anomaly charts from the ZEEE Project will provide the most coherent and complete gravity perspective available for this area. This article describes the efforts and accomplishments of the project to date.
Volcano collapse and tsunami generation in the Bismarck Volcanic Arc, Papua New Guinea
(Journal of volcanology and geothermal research, 2009) Silver, Eli; Day, Simon; Ward, Steve; Hoffmann, Gary; Llanes Estrada, María Pilar; Driscoll, Neal; Appelgate, Bruce; Saunders, Steve
During a cruise on the R/V Kilo Moana in 2004, we mapped 12 debris avalanches from volcanoes in the Bismarck volcanic arc, estimated their sizes and computed the size of potential tsunami run-up in major local population centers from these features. We used the towed side-scan instrument HAWAII MR1, the hull-mounted EM120 system for swath bathymetry and backscatter intensity, a shallow penetration chirp system, several bottom camera tows and selected cores. We calibrate our computations with the known tsunami run-up of the Ritter collapse. Even the small collapses may have had significant run-up on near-by coastlines. Had any of the collapses we have identified occurred in modern times each would affect a presently populated region of the coastline to a moderate or significant degree.
Gravity analysis offshore the Canary Islands from a systematic survey
(Marine Geophysical Researches, 2003) Carbo Gorosabel, Andrés; Muñoz Martín, Alfonso; Llanes Estrada, María Pilar; Álvarez García, Juan
As part of a systematic mapping program of the Hydrographic and Oceanographic Research Plan for the Spanish Exclusive Economic Zone (EEZ), gravity surveys were carried out offshore the Canary Islands. Using the gravity data collected during cruises between 1998 and 2000 aboard the RV Hesperides and satellite and land data, we construct free air and Bouguer anomaly maps and discuss the geodynamic implications. Using maps of Bouguer anomaly, free air anomaly, vertical derivative, long wavelength Bouguer anomaly and short wavelength anomaly, a detailed description of the gravity characteristics of the archipelago is presented, describing gravity anomalies from a geologic point of view. The character of the crust throughout the studied area has been defined, as well as high gradient zones that limit crustal blocks of different density. High gradient zones have been mapped for the first time and interpreted as fracture zones, taking into account geophysical and geological information. Gravity highs and lows have been studied and related to crustal, mantle and volcanic effects.
Batimetría multihaz del noreste de Gran Canaria (Islas Canarias)
(Geotemas, 2000) Llanes Estrada, María Pilar; Muñoz Recio, Araceli; Acosta, J.; Herranz, P.; Palomo, C.
The ZEE99 oceanographic cruise was carrided out aboard B.I.O. Hespérides by the Instituto Español de Oceanografía and the Instituto Hidrográfico de la Marina, and was located in Canary Islands. In order to study the bathymetry o f the Gran Canaria northeast ocean floor; a Simrad EMI 2 multi beam echosounder was used. These data allow us to produce a detailed bathymetric map and make it possible to infer the caracteristics and geologic processes that led to a major development in the investigation o f submarine geomorphology around the Canary Islands.