Geological Behavior (GBR)

The geology of the Sandakan town area provides a favourable setting for geomorphological hazards occurrences. The exposed rocks in the study area and its surrounding vary in types and ages, from Late Eocene-Early Miocene Neogene’s clastic sediment of the Garinono Formation, the Sandakan Formation and Volcanic Facies to vary recent Quaternary alluvial materials which are still being deposited. These rock units are dissected by numerous lineaments with complex structural styles developed during series of regional Tertiary tectonic activities. Rapid urbanization activities have caused changes in the land use. Urbanization processes may contribute to the exposure of impervious surface, loss of vegetation cover, modification of slope gradient and drainage systems. The last decade has seen slope failure, flash flood and erosion events, which have claimed lives, damaged properties and increased the cost of maintenance. The main factors causing geomorphological hazards occurrences in the study area are natural (geology, meteorology, topography and drainage system) and human factors (lack of proper planning, human activities and community’s attitude). Serious efforts to increase the community’s awareness to geomorphological hazards occurrences and reconstruction of natural ecosystem must be taken. To handle this issue, both prevention and mitigation are necessary. At the planning level a multi disciplinary approach to zoning, risk assessment and design with construction practices is recommended. This is to ensure that future activities will not cause further damage to natural environmental condition or ecosystem.

Earthquakes are one of the most common and widely distributed natural risks to life and property. There is a need to identify the possible risk by assessing the vulnerability of the research area. The topic on Earthquake Vulnerability Assessment (EVAs) in Malaysia is very new and received little attention from geoscientists and engineers. Taking the 5.0 Ranau Earthquake 2015 as research study, the research’s main objective was to identify the social vulnerability and environment vulnerability on that area. The framework was formulated semi quantitively through the development of database for risk elements (properties) based on the information from secondary data, literature review and fieldwork. The vulnerability parameter includes social status (injury, fatalities, safety, loss of accommodation and public awareness) and interference of environment (affected period, daily operation and diversity). Each considered parameter in the vulnerability parameter is allocated with certain index value ranges from 0 (0% damage/victims/period),0.25 (1-25% damage/victim/period), 0.50 (26-50% damage/victims/periods), 0.75 (damage/victims/period), and 1.0 (75-100% damage/victim/periods). The value obtained from field work are calculated by using formula and are classified into five classes of vulnerability namely class 1 (<0.20): Very Low Vulnerability: Class 2 (0.21-0.40): Low Vulnerability; Class 3 (0.41-0.60); Medium Vulnerability; Class 4 (0.61-0.80): High Vulnerability; and Class 5 (>0.81): Very High Vulnerability only. Results from this study indicate that a further study is needed to the area of high to very high vulnerability only. This approach is suitable as a guideline for preliminary development in the research area and potentially to be extended with different background and environments.

Sabah experienced moderate seismicity in the active fault zones located in Kundasang, Ranau of 6.0 MW within minor damage recorded at Sabah recently. The damage following the earthquake and more than 100 aftershocks affected 61 buildings such as schools, hospital and mosque, 22 roads and 22 slopes. Over the past 114 years, a total of 124 with magnitudes ranging from 2.9 to 6.0 are known to have occurred. The earthquake in Sabah that struck Ranau, carrying a moment magnitude of 6.0 on 5 June recently lasted for 30 seconds. This earthquake was the strongest to affect Malaysia since 1976 in Lahad Datu. The latest thesis in the Sabah region had been carried out in Kundasang, Kudat and two buildings in KK city. The objective was to presents the evaluation of soil sample taken in Kota Kinabalu (KK) city that could possibly subjected to low intensity earthquake effects. The evaluation of determination of the soil amplification factor is used to determine the influence of soil condition on buildings in KK city. With the input motion of Whittier Narrows (6.0 Mw, ts = 0.005 s) and KKM Ranau (5.9 Mw, ts = 0.01 s), the analysis of the maximum acceleration for PGA and PSA will be varies with the use on program of NERA and DEEPSOIL V5.1. From the appendixes as shown in appendix, it is known that most of their soils are consisting of a surface alluvium layer varying the thickness in between of approximately 5 m and 20 m in refer to some researcher. Most of the soil condition is reviewed that there are soil type of B, C, D and E in according to (Technical Committe B/525, 2005). This study shows that the soil amplification factors for each location in KK city are various with the input motion of 5.9 Mw, ts = 0.01 s and 6.0 Mw, ts = 0.005 s.

The geology along the Kimanis to Keningau Highway provides a favourable setting for engineering geological instability. The area is underlain by the Crocker Formation (Late Eocene to Early Miocene age) to vary recent Quaternary alluvial materials which are still being deposited. Crocker Formation consists mostly of interbedded grey sandstones and grey mudstones or shales. The sandstones are texturally immature where angular to subrounded quarts grains are cemented by clay minerals and occasionally by calcite. The Crocker Formation has also undergone intense deformation. The tectonic complexities influenced the physical and mechanical properties of the rocks, resulting in a high degree of weathering and instability. The weathered materials are unstable and may experience sliding due to by high pore pressure and intensively geomorphological processes. In this study, a total of 28 selected critical slope failures were studied and classified into two main groups: rock slope and soil slope. Failures in soil slopes (including embankments) are 18 (64 %) whereas 10 of all failures (36 %) of rock slope. Soil slope failures normally involved large volumes of failed material as compared much rock slopes, where the failures are mostly small. Of the 18 failures in soil slopes, 6 (33 %) are embankment failures making them 21 % of all types of failures. Kinematics rock slope analyses indicates that the variable potential of circular, planar, wedges and toppling failures modes as well as the combination of more than one mode of aforementioned failure. Rock and soil slopes stability analysis indicates that the factor of safety value as unsafe (0.50 to 0.96). The main factors causing slope failure occurrences in the study area are natural (geology, meteorology, topography and drainage system) and human factors (lack of proper planning, human activities and community’s attitude). Development planning has to consider the hazard and environmental management program. This engineering geological study should be prioritized and take into consideration in the initial step in all infrastructures program and it may play a vital role in landslide hazard and risk assessment to ensure the public safety.

The Miri Formation is continuously studied by many researchers in various aspects and disciplines in geology due to the important petroleum reservoir since the period of production in 1920-1941. The aim of this study is to analyse a basic principle of postulated type locality found in Miri area. A complete sequence of the Miri Formation (measured section) is exposed at Oil Well road which is related to the Miri Formation. The distribution of outcrops is widely distributed at a few localities in Miri region such as Tanjong Lobang, Airport road, Hospital road and Oil Well road. The rock formation is preserves a complete sequence of sedimentary facies established for the Miri Formation. The section comprises the following facies; facies 1: planar cross stratified (PcS), facies 2: swaley cross stratified (ScS), facies 3: swaley-Hummocky cross stratified (SHcS), facies 4: Hummocky cross stratified (HcS) and facies 5: parallel laminae facies. Those facies are interpreted to have been deposited from offshore, lower shoreface to foreshore setting at a shoreline system. This measured section found stands by itself without referring to another rock unit either lateral or vertical distribution except the information reported by former researchers that they used sub-surface data to evaluate other formation (lithostratigraphic unit) related to it.

Sebatik Island belongs to two countries; Malaysia (northwest) and Indonesia (southeast). The study only involved Malaysia’s area, covering an area about 200 km2. The area of study comprised of Sebatik Sandstone-Shale Member from Kalumpang Formation; is part of the Neogene sequence located in the northern part of the Tarakan Basin. The main objective of this study is to analyze the sedimentary facies, and then to interpret the paleoenvironment in the study area. There has been no such study ever conducted by any researcher in Sebatik Island, Malaysia. This study was carried out through systematic characterization of sedimentary structure parameters on rock outcrops in the field based on sedimentological methods. Regarding on that characterization, several facies had been identified; amongst them namely heterolithic facies that was divided into three subfacies; lenticular bedding, wavy bedding and flaser bedding. These subfacies are combined and linked into one facies association that describe of the shoreline environments. It is formed through drag and drop processes dominated by the tides influence. The discovery on Sebatik Island, Malaysia is in line with the setting of Meliat Formation, Indonesia.

This study was conducted to determine the value of Geological Strength Index (GSI), to predict rock mass properties, very unfavourable discontinuities combination and tunnel support pressure for rock bolts or shotcrete and to determine the suitability of GSI for a tunnel in Crocker Formation. Engineering geological mapping and discontinuity survey was done along the tunnel face as well as rock sampling. GSI values and the disturbance factor were obtained from field observation on the tunnel face. Point load and dry density test was conducted to determine the Uniaxial Compressive Strength (UCS) and unit weight, respectively. The rock mass properties, kinematic analysis and limit equilibrium analysis was used to determine the factor of safety (F.O.S) and pressure to stabilise the tunnel. The rock mass was characterised by 94.88 MPa UCS, 0.024 MN/m3 unit weight, widely space and high persistency. The GSI value is 50 with 0.8 disturbance factor. The cohesion, friction angle and tensile strength are 3.671 MPa, 25.20° and 0.056 MPa respectively. The friction angle was reduced by 5° due to lower shear strength of bedding plane. There are eight possibilities of discontinuities combinations on tunnel crown that have F.O.S lower than 2 and combination of joints 2, 4 and 6 has the maximum wedge volume of 28.37 m3. The maximum support pressure of rock bolts or shotcrete for F.O.S of 2 at the tunnel crown is 0.04 MN. The high F.O.S value may have been due to the overestimation of friction angle and cohesion of discontinuity plane. Then, this study shows that GSI system is unsuitable for the tunnel in study area which behave as anisotropic and structurally controls rock mass, but if needed, the values of rock mass properties, discontinuities combination and support pressure can be used for tunnel design.

An assessment of stability potential of rock slopes from Ranau, Sabah has been conducted using modified D-slope method. D-slope comprises of G-Rating determination and Potential Instability to assess the slope condition using field observations, laboratory analysis and microfabric analysis. 17 parameters have been done for G-Rating purpose including the type of rocks, weathering grade, existence of faults and joints, number of major sets, number of orientations, aperture, persistence and spacing of discontinuities, rainfall, hydraulic condition, height of slope, history of instability, porosity, strength, micro-petrographic and micro-fractures index. Kinematic analysis is used for Potential Instability analysis to determine the type of failures for each slope. This later is to determine the level of slope’s risk: No Risk, Low Risk, Moderate Risk or High Risk. Six slopes have been chosen from Trusmadi Formation and ultrabasic Rocks along Marakau – Ranau Sport Complex. Based on the results of G-Rating, only slope S1 and S4 have value more than 0.4 while other slopes have less than 0.4 which indicates stable slopes. Based on kinematic analysis, all slopes experienced wedge failures with S4 and S5 also have planar failure possibility which show that all slopes have potential instability. D-slope analysis indicates that slope S4 is considered as Moderate Risk with mitigation suggestions are rock anchor and soil nailing with further actions required. Slope S1 is categorized as Low Risk with suggestions of stream system inspection and vegetation on exposed area of the slopes, while other slopes (S2, S3, S5 and S6) have no suggestion for mitigation as been assessed as No Risk.

Coastal erosion is a concern to coastline management and it affects the socio-economic well-being of local communities. The rehabilitation of Selabat Mudflats Nature Reserve (SMNR) in Sarawak is one of the most impressive achievements of the “Mangrove and Suitable Tree Species Planting at the National Coastline Program” implemented by the Ministry of Natural Resources and Environment (NRE). The rehabilitation efforts began in 2009, where 20 hectares of Rhizophora mucronata were planted and followed by an additional 1.7 hectares of Casuarina equisetifolia. Previously, this area was a sandy coastline where coastal erosion occurred every year causing local loss of land and properties. However, through conservation and rehabilitation efforts, this area was restored and is now able to generate more income for local communities as well as playing a protective role against coastal erosion caused by coastal waves and strong winds. In 2016, this study was conducted to assess the economic impacts of SMNR rehabilitation. The findings from a sample of 42 households showed that the income generated for local communities around SMNR amounted to RM250, 320 per month or RM3, 003,840 per year. A non-user survey of 401 samples was also conducted, using Contingent Valuation Method to estimate the economic value of SMNR rehabilitation. The result showed the economic value of rehabilitation of SMNR was RM39 million for the year 2016 or RM195, 980 per hectare. These findings showed that the function of rehabilitation and conservation of mangroves forests against coastal erosion brings positive economic impacts. Rehabilitation and conservation of mangrove areas in Malaysia should be given more attention as global warming and rising sea level are going to have negative impacts on coastal settlements. Wise decision-making in the utilisation and allocation of limited resources is important particularly in the context of conflict between conservation and other development that led to its destruction.

Everyday it rains heavily during the monsoon period around December to January in Terengganu watershed especially near to the South China Sea is experiencing a flash flood. the flood is usually occurring in most of the states in Peninsular Malaysia. the use of Geographic information system to identify those zones which are vulnerable to flood risk was employed. The method is to characterize different hydrologic response units into subbasins which were adopted using the Soil Water Assesment Tool (SWAT). The geomorphic factors of soil, land use and slope have greatly influenced the water flow that causes the flood. the Terengganu watershed was delineated and the flood risk at individual subbasin parameter was simulated in form of real-time simulation. All the scenario within the catchment was calculated for easy mitigation. The flood risk models were developed for the purpose of planning and management. the HRUs are found to be vulnerable to flood risk with a greater impact of soil and land cover in the Terengganu River catchment area.