It has been established that wood decay and cavities in tree stems contribute significantly to tree failures. Several techniques have been reported by researchers for detecting wood decay and cavities in living trees. These techniques are reviewed in this study under two broad categories: invasive and non-invasive methods. The invasive methods include traditional (decay detecting drill, increment borer, and boroscope), radiographic, acoustic, and electrical resistivity techniques. The non-invasive methods comprise microwave scanning, magnetic resonance imaging, X-ray tomography, and traditional techniques involving the use of mallets. Two or more methods are usually combined to investigate the health status of a tree for comparison and validation of results. The prospects and challenges of the various techniques in diagnosing wood decay, cavities, and other structural defects in living trees are reported. This review aims to help researchers in this field identify areas of further work towards the efficient monitoring and management of forest and urban trees.

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The occurrence of earthquakes in oceanic trenches can pose a tsunami threat to lives and properties in active seismic zones. Therefore, the knowledge of focal depth, magnitude, and time distribution of earthquakes along the trenches is needed to investigate the future occurrence of earthquakes in the zones. The oceanic trenches studied, were located from the seismicity map on: latitude ?51°to ?53°a nd longitude-160°to 176°(Aleutian Trench), latitude ?40°to ?53°and longitude ?148°to ?165°(Japan Trench), and latitude-75°to-64°and longitude-15°to ?30°(Peru-Chile Trench). The following features of seismic events were considered: magnitude distribution, focal depth distribution, and time distribution of earthquake. The results obtained in each trench revealed that the earthquakes increased with time in all the regions. This implies that the lithospheric layer is becoming more unstable. Thus, tectonic stress accumulation is increasing with time. The rate of increase in earthquakes at the Peru-Chile Trench is higher than that of the Japan Trench and the Aleutian Trench. This implies that the convergence of lithospheric plates is higher in the Peru-Chile Trench. Deep earthquakes were observed across all the trenches. The shallow earthquakes were more prominent than intermediate and deep earthquakes in all the trenches. The seismic events in the trenches are mostly of magnitude range 3.0-4.9. This magnitude range may indicate the genesis of mild to moderate tsunamis in the trench zone in near future once sufficient slip would occur with displacement of water column.

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Geophysical investigation and microstudy of soil properties were carried out within Bowen University, for the characterization of the subsurface pattern in the area using vertical electrical sounding (VES) survey and evaluation of soil properties with a view to mapping subsurface geological features, such as weak and competent zones and to determine the overburden thickness of the area for pre-foundation studies for a proposed high-rise building. Four (4) VES was carried out in the study area employing schlumberger electrode configuration. The data collected were used to curve match and the results used for subsequent interpretation to reveal the depth, thickness and resistivity of the study area. In addition, soil samples were collected from three (3) selected points located at the entrance, centre and the end of the study area at about a depth 0-60 cm. Consequently, the VES results were presented as resist graph, which revealed the range of values for the depth (1.3 -24.5), thickness (1.3 -15.4 m) and resistivity (357.4 -6311.6 ohms), which was later used to generated the geoelectric maps of the study area. It was also observed that the result of the soil properties revealed that all the samples taken from the study area have low bulk density (1.41 g/cm 3 , 1.26 g/cm 3 , 1.36 g/cm 3 ), high particle density (2.81 g/cm 3 , 2.94 g/cm 3 , 3.16 g/cm 3 ), and high porosity (49.64%, 57.22%, 57.03%). In conclusion, it was observed that erection of high-rise building is not advisable within the study area since the results showed that the overburden (depth to basement) is generally thick mostly greater than 15 m. Also revealed from the microstudy of soil properties is that foundation stability should be properly managed, since a porous soil does not accommodate engineering activities except when an artificial basement is put in place.