Waterfalls of Maliau Basin—geoheritage of Sabah, Malaysian Borneo

The Maliau Basin, located in one of the remaining pristine rainforest in Sabah, produces some of the most spectacular waterfalls in Malaysia. The seven-tier Maliau Falls has become one of the major attractions for visitors to the basin. However, other waterfalls within the basin are not well known to visitors and their development rarely publicised. This paper highlights the development of waterfalls in this extremely remote basin. At least 28 waterfalls showing heights of more than 5 m have been mapped in this basin. The high density of waterfalls in the basin can be attributed to the right combination of geology, geomorphology and climate. A waterfall development model is proposed to explain the occurrence of the waterfalls. The basin which is made up of gently dipping sedimentary rock comprising of repetitive resistant sandstone layers and soft mudstone layers produces multi-storey waterfalls. Numerous vertical fractures within the rock layers, which constitute lines of geological weakness, assist river downcutting and the formation of narrow valley, ideal for waterfalls to form. The saucer-like shape of the basin is ideal for collecting rainwater to feed the waterfalls

An overview of earthquake science in Malaysia

This paper highlights the level of earthquake hazard in Malaysia, the challenges in mitigating earthquake hazard and the way forward on how to strengthen earthquake science in Malaysia. Earthquake hazard is regarded as low throughout Malaysia, with the exception of Sabah where it is considered moderate. This elevated level of a hazard was reinforced during the 2015 Ranau Earthquake, which killed 18 people. Despite this and other recent sizeable earthquakes, the earthquake hazard in Malaysia is poorly understood, yet the population has increased, and growth in buildings and infrastructure has risen. While much progress has been made since the 2015 Ranau earthquake in terms of the development of (i) national seismic hazard map; (ii) national seismic building code; and (iii) planning guideline in a high-risk earthquake area, there are still many challenges faced in mitigating earthquake hazard in Malaysia. There is still a lack of seismic, geological, geodetic and engineering data; insufficient seismic and geodetic monitoring network system; lack of trained human resources; and lack of public awareness. To ensure that earthquake hazard is properly quantified and mitigated some steps have to be taken, which includes (i) comprehensive geological, geotechnical and engineering studies; (ii) coordinated seismic and geodetic monitoring; (iii) human resource capacity building; (iv) coordinated public education; (v) allocation of special research and development grant; and (vi) setting up of a National Earthquake Research Centre

Pemuliharaan warisan geologi : kajian beberapa Geotapak Di Sabah

Kerlas kerja ini mengetengahkan isu berkaitan dengan pemuliharaan warisan geologi berdasarkan kajian kes tujuh geotapak yang terdapat di luar kawasan Taman Taman Sabah. Penilaian awal status pemuliharaan geotapak yang berada dalam kawasan tanah kerajaan negeri, hutan simpan, ladang kelapa sa wit, kuari dan tanah individu telah dilakukan. Pada kesemua kawasan di atas, pemilik tanah sama ada individu atau syarikat tidak terikat dengan mana-mana undang-undang khusus untuk menjaga geotapak yang dijumpai di kawasan mereka. Wa/aupun begitu, ada juga usaha pemilik individu atau syarikat untuk menjaga dan membangunkan geotapak yang boleh membawa faedah langsung kepada mereka. Memandangkan setiap geotapak itu mempunyai keistemewaan tersendiri dan berada pada keadaan yang berlainan, pemuliharaan warisan geologi memerlukan pendekatan yang berbeza. Bagi geotapak yang mempunyai tarikan semulajadi (ada nilai rekreasi dan estetik) pemilik tanah, sama ada individu, syarikat atau agensi kerajaan nampaknya sanggup untuk menjaga dan membangunkan geotapak itu atas inisiatif sendiri. Bagi geotapak yang kurang tarikan semulajadinya, pendekatan proaktif diperlukan untuk mewarlakannya sebagai warisan budaya melalui perundangan yang sedia ada. Apapun bentuk pemuliharaan dan pembangunan geotapak itu selepas ia diwarlakan, penglibatan kumpulan berkepentingan (stakeholders), terutama masyarakat tempatan, perlu ada agar ia berjaya

Engineering Geological Mapping On Slope Design In The Mountainous Area Of Sabah Western, Malaysia.

The geology in the mountainous area of Sabah western provides a favourable setting for engineering geological instability. The area is underlain by the Trusmadi Formation (Palaeocene to Eocene age), the Crocker Formation (Late Eocene to Early Miocene age) and vary recent Quaternary alluvial materials which are still being deposited. The argillaceous nature and intense deformation suffered by the Trusmadi Formation and the highly jointed sandstone and mudstone beds of the arenaceous Crocker Formation makes them highly susceptible to weathering and instability. The weathered materials are unstable and may experience sliding due to by high pore pressure and intensively of geomorphological processes. In this study, a total of 20 selected critical slope failures were studied and classified into two main groups; rock slope (ten) and soil slope (ten). Soil slope failures normally involved large volumes of failed material as compared much rock slopes, where the failures are mostly small to medium. 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 (0.56 to 0.95). The geological influence had transformed the slopes in the Sabah mountainous area to be highly unstable and susceptible to landslide occurrences. Six (6) related main parameters to the landslide occurrence in the study area were attributed; 1) local and regional geology, 2) hydrological and geohydrological, 3) mineralogical and micro structures, 4) local discontinuities structures, 5) physical and engineering properties of soil and rock, and 6) geomorphological processes which can help in evaluating landslide problems. Therefore, development planning has to consider the slope hazard and risk management. This engineering geological mapping may play a vital role in disaster risk reduction programme in Sabah to ensure the public safety and to be extend with different environment

Engineering Geological Study On The Slope Failure Along The Kimanis To Keningau Highway, Sabah, Malaysia.

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

Coastal processes and Geomorphologic characteristics of major coastal town in east Sabah for assesment of Tsunami impacts

The major coastal town of East Sabah, comprising of Sandakan, Lahad Datu, Semporna and Tawau are characterized by extensive mangrove swamps, narrow sandy beaches and rocky coastlines. Most of the town areas are built on reclaimed mangrove swamps. The Sandakan and Tawau town areas are exposed to the open Sulu and Celebes seas, respectively, whereas the towns of Lahad Datu and Semporna are sheltered from the open sea by the Sakar and Bum-bum islands, respectively. Numerical tsunami modeling, using worse-case scenarios indicate that all towns are exposed to tsunami waves up to 2 meters within 1 hour time. On a regional scale, Tawau area is found to be exposed to highest risk of tsunami due to its narrow shelf, followed by Sandakan and Lahad Datu areas. On a local scale, areas found to be of highest risks are settlements located along the coast, especially water villages located in all the town areas. Based on tsunami risk maps prepared for each town, a general plan for tsunami hazard mitigation is proposed, which includes tsunami hazard emergency evacuation route maps for each town area

ENGINEERING GEOLOGICAL ASSESSMENT (EGA) ON SLOPES ALONG THE PENAMPANG TO TAMBUNAN ROAD, SABAH, MALAYSIA

This study focused on the engineering geological investigation of slope failures along Penampang to Tambunan road, approximately 12th km to 101th km from Kota Kinabalu city, Sabah, Malaysia. The area is underlain by the Crocker Formation (Late Eocene to Early Miocene age) and the Quaternary Deposits (Recent age). These rock units show numerous lineaments with complex structural styles developed during several regional Tertiary tectonic activities. 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 31 selected critical slope failures were studied and classified into two main groups: rock slope and soil slope. Failures in soil slopes (including embankments) are 21 (67 %) whereas 10 of all failures (33 %) 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 21 failures in soil slopes, 15 (71 %) are embankment failures making them 48 % of all types of failures. Physical and mechanical properties of 84 soil samples indicated that the failure materials mainly consist of poorly graded to well graded materials of clayey loamy soils, which characterized by low to intermediate plasticity content (9 % to 28 %), containing of inactive to normal clay (0.34 to 1.45), very high to medium degree of swelling (5.63 to 13.85), variable low to high water content (4 % to 22 %), specific gravity ranges from 2.57 to 2.80, low permeability (9.66 X 10-3 to 4.33 X 10-3 cm/s), friction angle () ranges from 7.70˚ to 29.20˚ and cohesion (C) ranges from 3.20 KPa to 17.27 KPa. The rock properties of 10 rock samples indicated that the point load strength index and the uniaxial compressive strength range classified as moderately week. Kinematics 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 (0.52 to 0.98). Engineering geologic evaluation of the study area indicates that the slope failures took place when rock and soil materials were no longer able to resist the attraction of gravity due to a decrease in shear strength and increase in the shear stresses due to internal and external factors. Internal factors involve some factors change in either physical or chemical properties of the rock or soil such as topographic setting, climate, geologic setting and processes, groundwater condition and engineering characteristics. External factors involve increase of shear stress on slope, which usually involves a form of disturbance that is induced by man includes removal of vegetation cover, induced by vehicles loading and artificial changes or natural phenomenon such as tremors. Development planning has to consider the hazard and environmental management program. This engineering geological study may play a vital role in slope stability assessment to ensure the public safety

Flood risk assessment on selected critical infrastructure in Kota Marudu Town, Sabah, Malaysia

This study investigates the risk of flood on selected critical infrastructure in a flood-prone catchment in Sabah, Malaysia. Kota Marudu, located in the Bandau floodplain, one of the Sabah’s northern water catchments, was selected as the study site due to its frequent flood occurrence and large floodplain coverage. Two of its largest rivers, namely Sungai Bongon and Sungai Bandau, tends to flood during rainy season and cause temporary displacements of thousands of people living in the floodplain. A total of 362 respondents participated in the questionnaire survey in order to gather information on historical flood occurrence. Three flood depth groups were determined, which are 1) less than 0.3 meter, 2) 0.3 – 0.6 meter and 3) more than 0.6 meter, while three categories of critical infrastructure were defined, namely transportation system, communication system and buildings. It is found that the transportation system encounters the most severe impact as flood inundation increases, where 92% of the respondents believe that the transportation access should be abandoned when flood depth is more than 0.6m. The findings of this study will be used for detailed risk assessment, specifically on the vulnerability of the critical infrastructures to flood in this floodplain

Seismic signature of subduction termination from teleseismic P- and S-wave arrival-time tomography : the case of northern Borneo

Acknowledgments S.P. acknowledges support from the Natural Environmental Research Council (NERC) Grant NE/R013500/1 and from the European Union's Horizon 2020 Research and Innovation Program under Marie Skłodowska-Curie Grant Agreement 790203. We thank the TanDEM-X Science Communication Team (German Aerospace Center (DLR) e.V.) for providing TanDEM topographic data. We thank the NERC Geophysical Equipment Facility for loan 1038 and seismometers loaned by the University of Cambridge and Aberdeen. We would like to thank Zhong-Hai Li and an anonymous reviewer for their constructive feedback during the review process.Peer reviewedPostprin