College of Natural and Applied Sciences

Permanent URI for this community

https://repository.udsm.ac.tz/handle/123456789/6

Browse

Now showing 1 - 20 of 1351

THE 1994–1995 MANYARA AND KWAMTORO EARTHQUAKE SWARMS: VARIATION IN THE DEPTH EXTENT OF SEISMICITY IN NORTHERN TANZANIA
(SOUTH AFRICAN JOURNAL OF GEOLOGY,, 2009) Gabriel D. Mulibo
Seismicity within two earthquake swarms (mb 1.0 to 4.0) in northern Tanzania recorded by the 1994-1995 Tanzania Broadband Seismic Experiment has been investigated through event relocation, modelling of regional depth phases and examination of focal mechanisms. In the Manyara swarm, seismicity is distributed over a region ~20 km wide and extends to >30 km depth. Hypocenters correlate well with the Manyara Rift, and focal mechanisms of many events show normal faulting with nodal planes having the same north-northeast orientation as the Manyara Rift border fault. This result indicates that the events are consistent with slip along the border fault and related faults beneath the Manyara Rift, and shows that the faults extend into the lower crust. Seismicity in the KwaMtoro swarm is distributed over a region ~10 km wide but extends only to ~12 km depth. There are no mapped faults above the swarm, but a strong correlation between the north to south orientation of the swarm, the north to south orientation of nodal planes in focal mechanisms, and north to south striking extensional structures nearby, suggest that events in this swarm could be caused by slip on a system of rift faults. However, a magma-driven origin for either swarm cannot be ruled out either.
THE 1994–1995 MANYARA AND KWAMTORO EARTHQUAKE SWARMS: VARIATION INTHE DEPTH EXTENT OF SEISMICITY IN NORTHERNTANZANIA
(GeoScienceWorld, 2009-12) Mulibo G.D., and Nyblade A.A
Seismicity within two earthquake swarms (mb 1.0 to 4.0) in northern Tanzania recorded by the 1994-1995 Tanzania Broadband Seismic Experiment has been investigated through event relocation, modelling of regional depth phases and examination of focal mechanisms. In the Manyara swarm, seismicity is distributed over a region ~20 km wide and extends to >30 km depth. Hypocenters correlate well with the Manyara Rift, and focal mechanisms of many events show normal faulting with nodal planes having the same north-northeast orientation as the Manyara Rift border fault. This result indicates that the events are consistent with slip along the border fault and related faults beneath the Manyara Rift, and shows that the faults extend into the lower crust. Seismicity in the KwaMtoro swarm is distributed over a region ~10 km wide but extends only to ~12 km depth. There are no mapped faults above the swarm, but a strong correlation between the north to south orientation of the swarm, the north to south orientation of nodal planes in focal mechanisms, and north to south striking extensional structures nearby, suggest that events in this swarm could be caused by slip on a system of rift faults. However, a magma-driven origin for either swarm cannot be ruled out either.
2.67 Ga high-Mg andesites from the Musoma-Mara greenstone belt, northern Tanzania
(2008-07-01) Manya, Shukrani; Maboko, Makenya A. H.
Neoarchaean (2.67 Ga) High-Mg andesites occur in the Musoma-Mara greenstone belt, northern Tanzania. They are associated with dacites and Na-granitoids both of which are adakitic in composition. The high-Mg andesites are characterized by higher contents of MgO (2.42 – 9.47 wt %), Cr (41-797 ppm) and Ni (11-254 ppm) than those of normal island arc andesites. Their La/Yb ratios are 9.87 – 22.5 whereas their Sr/Y ratios are 20 – 131.These characteristics are similar to those shown by Cenozoic Setouchi High Magnesian Andesites (HMA). These rocks are characterized by 143Nd/144Nd ratios that range from 0.511062 ± 7 to 0.511308 ± 12 with corresponding εNd (t) of +0.44 and +1.81. The high contents of Mg, Cr and Ni argue in favour of equilibration of their parental magma with mantle peridotite whereas their relatively low La/Yb ratios argue against the involvement of garnet and amphibole as residual phases during partial melting. Thus, the high-Mg andesites are interpreted to have formed by partial melting of the mantle peridotite that has been fluxed by slab-derived fluids. Overall, the geochemical features of high-Mg andesites, their close association with adakitic rocks in the MMGB together with the short time interval taken for their emplacement are interpreted in terms of a ridge-subduction model. It is considered that such a model was important for generation of late Archaean continental crust.
The ~4-ka Rungwe Pumice (South-Western Tanzania): A wind-Still Plinian Eruption
(2011-05) Fontijn, Karen; Ernst, Gerald G. J.; Bonadonna, Costanza; Elburg, Marlina A.; Mbede, Evelyne I.; Jacobs, Patric
The ~4-ka trachytic Rungwe Pumice (RP) deposit from Rungwe Volcano in South-Western Tanzania is the first Plinian-style deposit from an African volcano to be closely documented focusing on its physical characterization. The RP is a mostly massive fall deposit with an inversely graded base. Empirical models suggest a maximum eruption column height HT of 30.5–35 km with an associated peak mass discharge rate of 2.8–4.8 × 108 kg/s. Analytical calculations result in HT values of 33 ± 4 km (inversion of TEPHRA2 model on grain size data) corresponding to mass discharge ranging from 2.3 to 6.0 × 108 kg/s. Lake-core data allow extrapolation of the deposit thinning trend far beyond onland exposures. Empirical fitting of thickness data yields volume estimates between 3.2 and 5.8 km3 (corresponding to an erupted mass of 1.1–2.0 × 1012 kg), whereas analytical derivation yields an erupted mass of 1.1 × 1012 kg (inversion of TEPHRA2 model). Modelling and dispersal maps are consistent with nearly no-wind conditions during the eruption. The plume corner is estimated to have been ca. 11–12 km from the vent. After an opening phase with gradually increasing intensity, a high discharge rate was maintained throughout the eruption, without fountain collapse as is evidenced by a lack of pyroclastic density current deposits.
A comprehensive review on CO2 thickeners for CO2 mobility control in enhanced oil recovery: Recent advances and future outlook
(Journal of Industrial and Engineering Chemistry, 2023-06-16) Emanuel X. Ricky; Grant Charles Mwakipunda; Edwin E. Nyakilla; Naswibu A. Kasimu; Chao Wang; Xingguang Xu
Carbon dioxide (CO2) has been utilized to recover the residual oil from the geological reservoirs through enhanced oil recovery (EOR) methods for over 50 years. Despite its long history of success as an EOR technique, CO2 flooding recovers only about 20–40% of the original oil in place (OOIP) from the geological reservoirs. The small amount of oil recovered by CO2 flooding is associated with the low viscosity of CO2 injected into the reservoir, resulting in CO2 viscous fingering, CO2 gravity override and unfavourable mobility. To address these problems, the CO2 viscosity needs to be enhanced considerably using CO2 thickeners or viscosifiers. Despite more than five decades of intensive research work in formulating and identifying effective CO2 thickeners such as polymers, surfactants, small molecules and nanoparticles; as yet none of these chemicals can be regarded as effective CO2 thickeners for EOR field applications. Thus, CO2 thickener is an interesting research topic for future studies to come up with effective and affordable CO2 thickeners for EOR field applications. This article presents the recent developments in CO2 thickening technologies in EOR. Furthermore, the CO2 thickening mechanisms, screening criteria, field scale applications, challenges and future research directions on CO2 thickeners are evaluated.
Abnormal white colouration in three species of insectivorous African bats
(2009-08) Howell, Kim
There are numerous reports in the literature of albinism in bats (Setzer, 1950; Verschuren, 1955; Walley, 1971, and Cerveny & Burger, 1977). Not all records of white or partially white bats represent cases of albinism as defined by Egoscue & Lewis (1 968), and emphasized by Quay (1970). Many authors note records of “partial albinism” which are actually examples of non-albinistic abnormalities in colouration. Of the two most recent reviews, only that of Walley (1971) correctly records separately examples of albinism
Absolute-convective instability of a mixed forced-free convection boundary layer
(Fluid Dynamics Research, 2010-08-18) Mureithi, Eunice; Denier, James
A spatio-temporal inviscid instability of a mixed forced-free convection boundary layer is investigated. The base flow considered is the self-similar flow with free-stream velocity ue xn. Such a boundary-layer flow presents the unusual behaviour of generating a region of velocity overshoot, in which the streamwise velocity within the boundary layer exceeds the free-stream speed.A linear stability analysis has been carried out. Saddle points have been located and a critical value for the buoyancy parameter, G0c 3.6896, has been determined below which the flow is convectively unstable and above which the flow becomes absolutely unstable. Two spatial modes have been obtained, one mode being convective in nature and the other absolute. The convective-type spatial mode shows mode crossing behaviour at lower frequencies. Thermal buoyancy is shown to be destabilizing to the absolutely unstable spatial mode.
Absolute-convective instability of mixed forced-free convection boundary layers
(2010-08) Mureithi, Eunice; Denier, James
A spatio-temporal inviscid instability of a mixed forced-free convection boundary layer is investigated. The base flow considered is the self-similar flow with free-stream velocity ue ~ xn. Such a boundary-layer flow presents the unusual behaviour of generating a region of velocity overshoot, in which the streamwise velocity within the boundary layer exceeds the free-stream speed. A linear stability analysis has been carried out. Saddle points have been located and a critical value for the buoyancy parameter, G0c ≈ 3.6896, has been determined below which the flow is convectively unstable and above which the flow becomes absolutely unstable. Two spatial modes have been obtained, one mode being convective in nature and the other absolute. The convective-type spatial mode shows mode crossing behaviour at lower frequencies. Thermal buoyancy is shown to be destabilizing to the absolutely unstable spatial mode.
Abundance and Diversity of Rodents at The Human-Wildlife Interface in Western Serengeti, Tanzania. African Journal of Ecology
(Wiley, 2006-07) Magige, Flora J.; Senzota, R. B. M.
In this paper we examine how climate change interacts with other disturbances to alter the functioning of a tropical ecosystem, the Serengeti in Tanzania. Tropical Africa has increasing temperatures and changes in rainfall. Long-term data have shown how the avifauna responds to the interaction of environmental change with other disturbances: (1) habitat modification through agriculture by limiting endemic species and top trophic levels. Rare species are lost so this is a problem for conservation. Top trophic levels are lost and the lack of predators then releases pests. This is a problem for natural resource management. (2) Disease and hunting cause slow change in the species complex. This can alter community dynamics depending on which species enter or leave. (3) Habitat fragmentation or decay can cause slow change. When this reaches a threshold there may be rapid change in the species composition causing multiple states. One lesson is that present-day ecosystem states and trends can only be understood in the context of past historical events. Another is that all systems change so this requires a new approach to conservation. Within protected areas, new boundaries or new areas will be required. Outside rewilding is required to support more biodiversity.
Abundance and diversity of rodents at the human–wildlife interface in Western Serengeti, Tanzania
(2006-09) Magige, Flora; Senzota, Ramadhani B. M.
Rodent species abundance and diversity in Western Serengeti are evaluated and discussed in relation to different levels of conservation status [Unprotected Area (UA), Game Reserve (GR) and National Park (NP)] and broad site differences in human livelihood activities. A total of 2170 individuals, spread over 16 rodent species, were caught in a capture-mark-recapture study which covered both the dry and wet seasons. The more humid site (Tabora B) in the northern part of Serengeti had the highest diversity of rodents followed by the Mihale site at the western extension. The driest site at Robanda had the lowest overall species diversity. Diversity also varied between the three levels of conservation status whereby the UA had the least diversity while the NP, which enjoyed the highest level of conservation status, had the highest diversity of rodents. Unprotected Area and NP plots at Tabora B showed a rodent species similarity index of 40%; all the other paired plots scored over 50% similarity indices, suggesting that, within a site, species composition did not vary significantly between the three levels of conservation status. The Robanda site had the highest (56%) overall abundance of rodents; Mihale and Tabora B sites had about the same level of rodent abundance (20 and 24% respectively). For the Mihale site, Mastomys natalensis ranked first followed by Arvicanthis niloticus and Tatera robusta, each of which contained 40, 38 and 16%, respectively, of all individuals caught at the site. For the Robanda site, the figures were 66%A. niloticus, 22%M. natalensis and 9%T. robusta; while for the Tabora B site the scores were 37%M. natalensis, 18%T. robusta and 11%Lemniscomys barbarus. The differences in diversity, species composition and population abundance appear to result largely from physiognomic vegetation types, and habitat perturbations caused by livelihood activities in Western Serengeti.
Abundance and Diversity of Seagrass and Macrofauna in the Intertidal Areas with and Without Seaweed Farming Activities in the East Coast of Zanzibar
(Tanzania Journal of Science, 2009-07) Lyimo, Thomas J.; Mvungi, Esther F.; Mgaya, Yunus D.
The diversity and abundance of seagrass and associated macrofauna were studied in transects with and without seaweed farms at Chwaka Bay and Jambiani, in the East Coast of Zanzibar. Eight seagrass species, namely Cymodocea rotundata, Cymodocea serrulata, Thalassia hemprichii,Thalassodendron ciliatum, Syringodium isoetifolium, Halodule uninervis, Halophila ovalis and Enhalus acoroides were recorded in the transects. The mean total biomass of seagrass at Chwaka Bay ranged from 142.4 ± 70.71 to 1652 ± 772.7 g dw/m2 and 212.9 ± 146.2 to 1829 ± 1692 gdw/m2 in station with and without seaweed farms, respectively. At Jambiani, the mean total biomass ranged from 880.4 ± 336.8 to 3467 ± 549.9 and 203.4 ± 102.4 to 3810 ± 2770 g dw/m2 in station with and without seaweed farms, respectively. The overall total biomass of seagrasswas significantly lower (KW = 108.7, p < 0.0001) in station with seaweed farms than in stations without seaweed farms. A total of 93 macrofauna species representing 60 families were encountered and the mean density ranged from 910 to 6990 individuals/m2 at Chwaka Bay andJambiani in stations with and without seaweed farms respectively. The most common macrofauna species were Codakia punctata, Meropesta nicobarica, Echinometra mathaei, Pinna muricata and Clibanarius emystemus. It was shown that the macrofauna abundance and diversity was higher in stations without seaweed farms than in the stations with seaweed farms, which could be due to activities associated with seaweed farming which contributed to the loss of diversity and biomass of flora and macrofauna of the seagrass meadows.
Abundance and roosting ecology of chameleons in the Eastern Arc Mountains of Tanzania and potential effects of harvesting
(2011-12) Patrick, David A.; Shirk, Philip; Vonesh, James R.; Harper, Elizabeth B.; Howell, Kim
Harvesting of chameleons from the East Usambara Mountains of Tanzania for the exotic pet trade is of concern due to the high rates of habitat loss in this region and the fact that many of the species are endemic or near endemic to this isolated montane forest. Export of the majority of chameleons found in the East Usambaras is regulated by their listing under CITES Appendix II. To ensure harvesting is sustainable, however, greater knowledge of the ecology of species is needed. We conducted this study in and around Amani Nature Reserve in the East Usambara Mountains during August 2009. We used transects on the forest edge and interior to gather baseline data relating to the ecology of chameleons and to assess if any effects of harvesting on populations could be detected. We compared abundance of chameleons between forest edge and interior, the age/size of species, and sex-ratios between these two habitat types. We observed 108 chameleons during surveys, representing seven species. Some species were restricted to forest interior while others were only found on forest edges. When comparing age/size and sex ratios of the most valued species for the exotic pet trade, Trioceros deremensis, we found a strong female sex-bias in adults only, and that adult females were larger than adult males. This is in contrast to reports in published literature showing that males are capable of growing larger than females. Based on the low abundance of some species, we suggest careful consideration of future export quotas under CITES. Further investigation into the potential reasons for the size and sex-ratios of T. deremensis is also needed.
Academic Journals Food Preference of the Sea Urchin Tripneustes Gratilla (Linnaeus, 1758) In Tropical Seagrass Habitats at Dar Es Salaam, Tanzania
(2010-12) Lyimo, Thomas J.; Mamboya, Florence; Hamisi, Mariam; Lugomela, Charles
The sea urchin Tripneustes gratilla is the most well-known seagrass grazer in the Western Indian Ocean and a few cases of overgrazing have been reported. However, few studies on their feeding preference have been performed in this region. In this study, the food items in the gut contents of T. gratilla collected from seagrass beds and in a bare sediment in intertidal areas of Dar es Salaam, Tanzania, were analysed and compared to their availability in the surrounding environment. A total of 59 micro and macro-algae species were identified from the environment and the guts of T. gratilla, of which 48 were found in both gut contents and the environment. Gut contents of T. gratilla collected from mono specific seagrass habitats were dominated by the species in which they were found. In a mixture of four different seagrass species, Syringodium isoetifolium was preferred (with electivity indices (E*) of +0.36) while Cymodocea rotundata, Halodule uninervis and Thalassia hemprichii were slightly avoided (E* = -0.24, -0.22 and -0.22, respectively). We concluded that T. gratilla generally feeds on available seagrass species. However, in the presence of different types of seagrasses it showed preference to S. isoetifolium possibly due to presence of high epiphyte load which may increase its palatability.
Accumulation of Copper and Zinc and their Effects on Growth and Maximum Quantum Yield of the Brown Macroalga Padina Gymnospora
(2008) Mamboya, Florence; Pratap, Harish B.; Mtolera, M.; Björk, Mats
Accumulation and the effects of copper and zinc on the macroalga Padina gymnospora were assessed in the laboratory after artiﬁcial exposure to copper and zinc (separately or in combination). Exposure concentrations of copper used were 0, 25, 50, 100, 500 and 1,000 µg l-1. Concentrations of zinc exposure were 0, 50, 100, 250, 1,000 and 5,000 µg l-1. The simultaneous (or combined) addition of copper and zinc (Cu+Zn) involved 25+50, 50+100, 100+250, and 500+1,000 µg l-1. Accumulation patterns were determined by measuring tissue contents of copper and zinc, while the tolerance was assessed by measuring growth rate and photosynthetic performance, as maximum quantum yield (Fv/Fm). Furthermore, the inﬂuence of major nutrients (phosphates and nitrates) on algal-metal-accumulation was estimated after additions of nitrate (1, 10 and 20 mg l-1) and phosphate (0.1, 1 and 2 mg l-1). The data obtained showed that the accumulation increased linearly with the increase in metal concentration in the growth media. However, the presence of additional nitrate and phosphate reduced both the metal accumulation and their toxic effects. Both algal growth rate and maximum quantum yields were negatively affected in proportion to the increase in metal concentrations and exposure time. At exposures to 50, 100 and 500 µg l-1 copper, inhibition in growth was greater than 50%, while an exposure to 1,000 µg l-1of zinc was needed to cause the same effect on growth and Fv/Fm. Growth rate was a more sensitive indicator of stress than maximum quantum yield in response to exposure to copper and zinc Accumulation of Copper and Zinc and their Effects on Growth and Maximum Quantum Yield of the Brown Macroalga Padina Gymnospora
Accumulation of Copper and Zinc and their Effects on Growth and Maximum Quantum Yield of the Brown Macroalga Padina Gymnospora. Western Indian Ocean J. Mar. Sci. 6(1):17-28 (2007)
(2008) Mamboya, Florence A.; Pratap, Harish B.; Mtolera, Matern; Björk, Mats
Accumulation and the effects of copper and zinc on the macroalga Padina gymnospora were assessed in the laboratory after artificial exposure to copper and zinc (separately or in combination). Exposure concentrations of copper used were 0, 25, 50, 100, 500 and 1,000 µg l-1. Concentrations of zinc exposure were 0, 50, 100, 250, 1,000 and 5,000 µg l-1. The simultaneous (or combined) addition of copper and zinc (Cu+Zn) involved 25+50, 50+100, 100+250, and 500+1,000 µg l-1. Accumulation patterns were determined by measuring tissue contents of copper and zinc, while the tolerance was assessed by measuring growth rate and photosynthetic performance, as maximum quantum yield (Fv/Fm). Furthermore, the influence of major nutrients (phosphates and nitrates) on algal-metal-accumulation was estimated after additions of nitrate (1, 10 and 20 mg l -1) and phosphate (0.1, 1 and 2 mg l-1). The data obtained showed that the accumulation increased linearly with the increase in metal concentration in the growth media. However, the presence of additional nitrate and phosphate reduced both the metal accumulation and their toxic effects. Both algal growth rate and maximum quantum yields were negatively affected in proportion to the increase in metal concentrations and exposure time. At exposures to 50, 100 and 500 µg l-1 copper, inhibition in growth was greater than 50%, while an exposure to 1,000 µg l-1of zinc was needed to cause the same effect on growth and Fv/Fm. Growth rate was a more sensitive indicator of stress than maximum quantum yield in response to exposure to copper and zinc.
Acquisition of a Unique Onshore/Offshore Geophysical and Geochemical Dataset in the Northern Malawi (Nyasa) Rift
(Seismological Research Letters, 2016-09-07) Shillington, Donna J.; Gaherty, James B.; Ebinger, Cynthia J.; Scholz, Christopher A.; Selway, Kate; Nyblade, Andrew A.; Bedrosian, Paul A.; Class, Cornelia; Nooner, Scott L.; Pritchard, Matthew E.; Elliott, Julie; Chindandali, Patrick R. N.; Mbogoni, Gaby; Ferdinand, Richard Wambura; Boniface, Nelson; Manya, Shukrani; Kamihanda, Godson; Saria, Elifuraha; Mulibo, Gabriel; Salima, Jalf; Mruma, Abdul; Kalindekafe, Leonard; Accardo, Natalie J.; Ntambila, Daud; Kachingwe, Marsella; Mesko, Gary T.; McCartney, Tannis; Maquay, Melania; O’Donnell, J. P.; Tepp, Gabrielle; Mtelela, Khalfan; Trinhammer, Per; Wood, Douglas; Aaron, Ernest; Gibaud, Mark; Rapa, Martin; Pfeifer, Cathy; Mphepo, Felix; Gondwe, Duncan; Arroyo, Gabriella; Eddy, Celia; Kamoga, Brian; Moshi, Mary
The Study of Extension and maGmatism in Malawi aNd Tanzania (SEGMeNT) project acquired a comprehensive suite of geophysical and geochemical datasets across the northern Malawi (Nyasa) rift in the East Africa rift system. Onshore/offshore active and passive seismic data, long‐period and wideband magnetotelluric data, continuous Global Positioning System data, and geochemical samples were acquired between 2012 and 2016. This combination of data is intended to elucidate the sedimentary, crustal, and upper‐mantle architecture of the rift, patterns of active deformation, and the origin and age of rift‐related magmatism. A unique component of our program was the acquisition of seismic data in Lake Malawi, including seismic reflection, onshore/offshore wide‐angle seismic reflection/refraction, and broadband seismic data from lake‐bottom seismometers, a towed streamer, and a large towed air‐gun source.
Acquisition of a Unique Onshore/Offshore Geophysical and Geochemical Dataset in the Northern Malawi (Nyasa) Rift
(GeoScienceWorld, 2016-12) Donna J. Shillington, James B. Gaherty, Cynthia J. Ebinger, Christopher A. Scholz, Kate Selway, Andrew A. Nyblade, Paul A. Bedrosian, Cornelia Class, Scott L. Nooner, Matthew E. Pritchard, Julie Elliott, Patrick R. N. Chindandali, Gaby Mbogoni, Richard Wambura Ferdinand, Nelson Boniface, Shukrani Manya, Godson Kamihanda, Elifuraha Saria, Gabriel Mulibo, Jalf Salima, Abdul Mruma, Leonard Kalindekafe, Natalie J. Accardo, Daud Ntambila, Marsella Kachingwe, Gary T. Mesko, Tannis McCartney, Melania Maquay, J. P. O’Don- nell, Gabrielle Tepp, Khalfan Mtelela, Per Trin- hammer, Douglas Wood, Ernest Aaron, Mark Gibaud, Martin Rapa, Cathy Pfeifer, Felix Mphepo, Duncan Gondwe, Gabriella Arroyo, Celia Eddy, Brian Kamoga, and Mary Moshi
The Study of Extension and maGmatism in Malawi aNd Tanzania (SEGMeNT) project acquired a comprehensive suite of geophysical and geochemical datasets across the northern Malawi (Nyasa) rift in the East Africa rift system. Onshore/offshore active and passive seismic data, long‐period and wideband magnetotelluric data, continuous Global Positioning System data, and geochemical samples were acquired between 2012 and 2016. This combination of data is intended to elucidate the sedimentary, crustal, and upper‐mantle architecture of the rift, patterns of active deformation, and the origin and age of rift‐related magmatism. A unique component of our program was the acquisition of seismic data in Lake Malawi, including seismic reflection, onshore/offshore wide‐angle seismic reflection/refraction, and broadband seismic data from lake‐bottom seismometers, a towed streamer, and a large towed air‐gun source.
Acquisition of a Unique Onshore/Offshore Geophysical and Geochemical Dataset in the Northern Malawi (Nyasa) Rift
(Seismological Research Letters, 2016) Donna J. Shillington, James B. Gaherty, Cynthia J. Ebinger, Christopher A. Scholz, Kate Selway, Andrew A. Nyblade, Paul A. Bedrosian, Cornelia Class, Scott L. Nooner, Matthew E. Pritchard, Julie Elliott, Patrick R. N. Chindandali, Gaby Mbogoni, Richard Wambura Ferdinand, Nelson Boniface, Shukrani Manya, Godson Kamihanda, Elifuraha Saria, Gabriel Mulibo, Jalf Salima, Abdul Mruma, Leonard Kalindekafe, Natalie J. Accardo, Daud Ntambila, Marsella Kachingwe, Gary T. Mesko, Tannis McCartney, Melania Maquay, J. P. O’Donnell, Gabrielle Tepp, Khalfan Mtelela, Per Trinhammer, Douglas Wood, Ernest Aaron, Mark Gibaud, Martin Rapa, Cathy Pfeifer, Felix Mphepo, Duncan Gondwe, Gabriella Arroyo, Celia Eddy, Brian Kamoga, and Mary Moshi
The Study ofExtension andmaGmatism inMalawi aNdTanzania (SEGMeNT) project acquired a comprehensive suite of geophysical and geochemical datasets across the northern Malawi (Nyasa) rift in the East Africa rift system. Onshore/offshore active and passive seismic data, long-period and wideband magnetotelluric data, continuous Global Positioning System data, and geochemical samples were acquired between 2012 and 2016. This combination of data is intended to elucidate the sedimentary, crustal, and upper-mantle architecture of the rift, patterns of active deformation, and the origin and age of rift-related magmatism. A unique component of our program was the acquisition of seismic data in LakeMalawi, including seismic reflection, onshore/offshore wide-angle seismic reflection/refraction, and broadband seismic data from lake-bottom seismometers, a towed streamer, and a large towed air-gun source.
Activation Energy of Thermal Decomposition of LaC2O4Br
(Kluwer Academic Publishers, 1991) Lugwisha, Esther H. J.; Mulokozi, A. M.; Masabo, M. K. J.
The activation energy of the thermal decomposition of finely ground LaC2O4Br was determined according to the method of Ozawa asE a=203.83 kJ mol–1. As compared to the value for the parent oxalate La2(C2O4)3 E a=130 kJ/mol), this value is higher by about 70 kJ/mol, which is consistent with the increased interaction between the metal and oxalate ions. The substitution of Br by Cl does not affect the decomposition kinetics profoundly.Gem der Methode von Ozawa wurde die Aktivierungsenergie der thermischen Zersetzung von fein zermahlenem LaC2O4Br mitE a=208.83 kJ/mol bestimmt. Beim Vergleich mit dem entsprechenden Wert fr die Mutterverbindung La2(C2O4)3 (E a=130 kJ/mol) erweist sich dieser Wert um etwa 70 kJ/mol hher, was mit der verstrkten Wechselwirkung zwischen Metall- und Oxalationen bereinstimmt. Der Ersatz von Br durch Cl hat keinen tiefgreifenden Einflu auf die Kinetik der Zersetzung
Active Fault Mapping in Karonga-Malawi after the December 19, 2009 Ms 6.2 Seismic Event
(Elsevier, 2015) Macheyeki, Athanas S.; Mdala, Hassan; Chapola, Lostina S.; Manhiça, V. J.; Chisambi, Joshua; Feitio, Paulino; Ayele, Atalay; Barongo, J.; Ferdinand, Richard W.; Ogubazghi, G.; Goitom, B.; Hlatywayo, Dumisani J.; Kianji, Gladys; Marobhe, I.; Mulowezi, A.; Mutamina, Daniel; Mwano, J. M.; Shumba, Blessing; Tumwikirize, I.
The East African Rift System (EARS) has natural hazards – earthquakes, volcanic eruptions, and landslides along the faulted margins, and in response to ground shaking. Strong damaging earthquakes have been occurring in the region along the EARS throughout historical time, example being the 7.4 (Ms) of December 1910. The most recent damaging earthquake is the Karonga earthquake in Malawi, which occurred on 19th December, 2009 with a magnitude of 6.2 (Ms). The earthquake claimed four lives and destroyed over 5000 houses. In its effort to improve seismic hazard assessment in the region, Eastern and Southern Africa Seismological Working Group (ESARSWG) under the sponsorship of the International Program on Physical Sciences (IPPS) carried out a study on active fault mapping in the region. The fieldwork employed geological and geophysical techniques. The geophysical techniques employed are ground magnetic, seismic refraction and resistivity surveys but are reported elsewhere. This article gives findings from geological techniques. The geological techniques aimed primarily at mapping of active faults in the area in order to delineate presence or absence of fault segments. Results show that the Karonga fault (the Karonga fault here referred to as the fault that ruptured to the surface following the 6th–19th December 2009 earthquake events in the Karonga area) is about 9 km long and dominated by dip slip faulting with dextral and insignificant sinistral components and it is made up of 3–4 segments of length 2–3 km. The segments are characterized by both left and right steps. Although field mapping show only 9 km of surface rupture, maximum vertical offset of about 43 cm imply that the surface rupture was in little excess of 14 km that corresponds with Mw = 6.4. We recommend the use or integration of multidisciplinary techniques in order to better understand the fault history, mechanism and other behavior of the fault/s for better urban planning in the area.

Browse

Browsing College of Natural and Applied Sciences by Title

Results Per Page

Sort Options