The ∼1245 yr BP Asososca maar: New advances on recent volcanic stratigraphy of Managua (Nicaragua) and hazard implications

Influence of the substrate on maar–diatreme volcanoes — An example of a mixed setting from the Pali Aike volcanic field, Argentina

“…The youngest craters have diameter/depth ratios between 3 and 7 (dashed lines). Data sources: Asososca (Nicaragua) - Pardo et al (2008); Atexcac (Mexico) -Carrasco-Núñez et al (2007); Eledoi (Tanzania) - Dawson and Powell (1969); Elegante and Molina North (Mexico) - Wood (1974) and Gutmann (1976); Gour de Tazenat, Lac D'issarlès and Lac Pavin (France) -crater dimensions from Noll (1967), country rock descriptions from Juvigé et al (1993), Bozon (1963) and Boivin et al (1982), respectively; Joya Honda (Mexico) -Aranda- Gómez and Luhr (1996); Nilahue (Chile) - Muller and Veyl (1956); PAVF East Maar -this study; Tecuitlapa (Mexico) -Ort and Carrasco-Núñez (2009); Ubehebe (California, USA) - Crowe and Fisher (1973); Ukinrek West and Ukinrek East (Alaska) - Kienle et al (1980); hard substrate maars from the West Eifel volcanic field (Germany) -Büchel (1993). In the West Eifel, as in other volcanic fields, older maars tend to be shallower than young maars for a certain diameter, due to erosion.…”

International Lateinamerika-Kolloquium 2009

“…comm.). These, and the radiocarbon dates of the pottery-bearing paleosoils (1 245 ± 125 and 535 ± 110 a BP) obtained by Pardo et al (2008) infer an age between 1.2 and 0.6 ka for the NT. The recurrence of an eruption of this magnitude at Nejapa maar or a neighboring site and similar eruptive and transport mechanisms would represent a major hazard and risk to the densely populated western suburb of Managua, a city that is expanding rapidly towards the west.…”

“…1-3, 24148 Kiel, Germany Juanita.Rausch@gmx.de Nejapa maar (2.5 x 1.4 km, c. 120 m deep), the largest maar along the 15 km long Holocene Nejapa Miraflores Lineament (NML), is unequivocally the source vent of the youngest widespread basaltic tholeiitic tephra blanket (Nejapa Tephra: NT) in western central Nicaragua, as shown by isopachs and isopleths (Rausch and Schmincke, 2008). Pardo et al (2008) related the same deposits to Asososca maar which we infer to be the source of an older tephra deposit. The NT covers an area of >10 km² in western/northwestern Managua.…”

Nejapa Tephra: The youngest (c. 1kaBP) highly explosive hydroclastic eruption in western Managua (Nicaragua)

“…The soil overlying NT contains pottery related to the Ometepe technique dated as between 1350 and 1550 CE (650-450 a BP). These, and the radiocarbon dates of the pottery-bearing paleosols (1245 ± 125 and 535 ± 110 a BP) obtained by Pardo et al (2008) indicate that Nejapa Maar erupted between c. 1.2 and 0.6 ka BP. Future eruptions in this area of similar magnitude, eruptive and transport mechanisms would represent a major hazard and risk to the densely populated western suburbs of Managua, a city expanding rapidly westward.…”

“…The youngest up to 20-m-thick bedded tephra deposits exposed basically west of Asososca Maar and along the new road to León and north of Motastepe Scoria Cone (MSC) (Fig. 2) were thought to have had their source in Asososca Maar (Weiss, 2004;Pardo et al, 2008Pardo et al, , 2009). Our work clearly shows, however, that Nejapa Maar and not Asososca Maar is the source for the thick young tephra deposits mantling the area north and west of Nejapa Maar.…”