An investigation of the structure beneath Magadi area in southern Kenya rift using gravimetric data

Magadi area is located in the southern part of the Kenyan rift, an activecontinental rift that is part of the East African Rift system. Local seismic activity monitored previously around Lake Magadi revealed an earthquake cluster caused by swarm activity in the rift centre at shallow depths, which was probably triggered by magma movements. There was need for a follow-up to locate any body at depth with sufficient density contrast that may represent magmatic intrusions. Gravity measurements were carried out in 58 established stations and data from 52 other stations merged from existing coverage of previous measurements. Necessary corrections were applied to the gravity data and a Bouguer contour map prepared. Euler deconvolution technique was used to image depth to the causative bodies along selected profiles on the Bouguer anomaly map. Two  dimensional gravity forward models of the subsurface structure were generated by using Euler depth solutions in the start models. Among others, a unique body of density of 3.20 gcm-3 was modelled on the northern region near little Magadi at a depth of approximately 0.4 km. The location of the body coincides with the area where earthquake swarm occurs. Such a body of high density contrasts may be caused by mafic intrusions into the crust. Discontinuities in Euler solution cluster along the profiles indicated buried faults in the volcanic rift infill. The high seismicity may hence be associated to magma intrusions.Key words: Gravity, Bouguer anomaly, Euler Deconvolution, Keny

Spectral analysis of ground magnetic data in Magadi area, Southern Kenya rift

The area surrounding Lake Magadi in the southern Kenya rift is characterized by hot springs that issue from fractures distributed along the shores of the lake. Presence of earthquake swarms that cluster in northern margin of Lake Magadi strongly indicate magmatic activity in the area. This study was done as a follow-up to investigate depth to the heat source possibly causing high seismic activity and high heat flow in the area. A ground magnetic survey was conducted to investigate geothermal potential of the area and a magnetic anomaly contour map prepared. Spectral analysis involving determining power spectrum was applied to magnetic data along selected profiles cutting through discerned anomalies. Spectral analysis results suggest that the Curie-point isotherm depth under Magadi ranges from 5.20 km to 8.30 km. Estimated vertical temperature gradients along the profiles ranges from 111.53°C/km to 69.92°C/km. The hightemperature gradients and relatively shallow Curie point depths indicates high heat flow which suggests presence of a hot magmatic intrusion

Maternal and neonatal outcomes after caesarean delivery in the African Surgical Outcomes Study: a 7-day prospective observational cohort study.

BACKGROUND: Maternal and neonatal mortality is high in Africa, but few large, prospective studies have been done to investigate the risk factors associated with these poor maternal and neonatal outcomes. METHODS: A 7-day, international, prospective, observational cohort study was done in patients having caesarean delivery in 183 hospitals across 22 countries in Africa. The inclusion criteria were all consecutive patients (aged ≥18 years) admitted to participating centres having elective and non-elective caesarean delivery during the 7-day study cohort period. To ensure a representative sample, each hospital had to provide data for 90% of the eligible patients during the recruitment week. The primary outcome was in-hospital maternal mortality and complications, which were assessed by local investigators. The study was registered on the South African National Health Research Database, number KZ_2015RP7_22, and on ClinicalTrials.gov, number NCT03044899. FINDINGS: Between February, 2016, and May, 2016, 3792 patients were recruited from hospitals across Africa. 3685 were included in the postoperative complications analysis (107 missing data) and 3684 were included in the maternal mortality analysis (108 missing data). These hospitals had a combined number of specialist surgeons, obstetricians, and anaesthetists totalling 0·7 per 100 000 population (IQR 0·2-2·0). Maternal mortality was 20 (0·5%) of 3684 patients (95% CI 0·3-0·8). Complications occurred in 633 (17·4%) of 3636 mothers (16·2-18·6), which were predominantly severe intraoperative and postoperative bleeding (136 [3·8%] of 3612 mothers). Maternal mortality was independently associated with a preoperative presentation of placenta praevia, placental abruption, ruptured uterus, antepartum haemorrhage (odds ratio 4·47 [95% CI 1·46-13·65]), and perioperative severe obstetric haemorrhage (5·87 [1·99-17·34]) or anaesthesia complications (11·47 (1·20-109·20]). Neonatal mortality was 153 (4·4%) of 3506 infants (95% CI 3·7-5·0). INTERPRETATION: Maternal mortality after caesarean delivery in Africa is 50 times higher than that of high-income countries and is driven by peripartum haemorrhage and anaesthesia complications. Neonatal mortality is double the global average. Early identification and appropriate management of mothers at risk of peripartum haemorrhage might improve maternal and neonatal outcomes in Africa. FUNDING: Medical Research Council of South Africa.Medical Research Council of South Africa