Probabilistic seismic hazard assessment of East Malaysia using proposed empirical GMPE for shallow crustal earthquake

East Malaysia has witnessed an increase in low to moderate seismic activities due to a few active fault lines. While damaging earthquakes are fortunately rare, from historical records ranging between 1874 and 2014, the region already experienced devastating earthquake with a magnitude MW 5.2 in Sarawak, MW 5.8 in Lahad Datu and just recently with a magnitude MW 6.0 in Ranau. Over the years, a total of 159 with magnitudes ranging from 2.9 to 6.0 are known to have occurred. The effects of the earthquakes should be anticipated in order to mitigate the catastrophic failure of structures. In the seismic design of structures, the most critical part is the development of seismic design ground motion. In order to develop this ground motion, seismic hazard analysis such as probabilistic seismic hazard analysis (PSHA) is required. This study presents technical research into seismic hazard assessment for East Malaysia based on three objectives. The first objective is to determine the fault characteristics mechanism and layouts for the region. Next, to produce spectral ground motion prediction equation (GMPE) for the region due to scarcity and incompatible equation of GMPE from other region. Then, to determine the peak ground acceleration (PGA) throughout the region to be plot inside hazard map in terms of 10% and 2% probability of exceedance (PE) in design time period of 50 years with respect to 475 and 2,475 years return period. Since there is limited information regarding the fault sources in East Malaysia, the relevant source zones are divided into three different possible earthquake source (far-field and near-field due to background seismicity and local fault). In general, the plot of the new generated GMPE accurately represents an earthquake condition in East Malaysia. The hazard map shows the PGA values for 10% probability of exceedance is in the range of 0 to 250 cm/s2 and 2% probability of exceedance in the range of 20 to 400 cm/s2. In conclusion, the main contributor to hazard is dominated by local fault sources with Sabah has the highest seismic hazard level than Sarawak

Assessment of seismic vulnerability in reinforced concrete buildings in Tawau, Sabah: A study on damage potential

Tawau located in Sabah is deemed to possess a moderate level of seismic activity, primarily because previous earthquakes were concentrated in the Lahad Datu-Tawau region due to the existence of an active fault. Regrettably, a significant number of reinforced concrete (RC) buildings in this area lack awareness and comprehension of earthquake-resistant construction practices, which necessitate the evaluation of building vulnerability in high-seismichazard zones. The goals of this study are to conduct fieldwork for the evaluation of the damage potential on 105 existing RC buildings and develop a building damage map in the Tawau area. This entails employing Rapid Visual Screening (RVS) surveys in accordance with the FEMA P-154 guidelines, employing a scoring system to assess the potential for damage in buildings, and subsequently presenting the results on a map. The results of this survey reveal that most buildings in this study exhibit plan irregularities and vertical irregularities in their beams do not align with columns and weak or/and soft story, respectively. This survey concludes that the most prevalent damage potential among the surveyed buildings in this area is Grade 3, followed by Grade 4, with the least prevalent being buildings with a Grade 2 damage potential

Seismic vulnerability assessment in Kota Kinabalu, Sabah

Sabah has witnessed an increasingly low to moderate number of seismic activities throughout the years due to active Mensaban and Lobou-Lobou faults lines. Vulnerability level of older buildings in Sabah, designed and built on the basis of older codes of practice poses a significant threat to life safety and structural capacities of the existing buildings. This paper presents a framework of preliminary seismic vulnerability assessment of existing buildings in Kota Kinabalu. Building stocks include major government buildings and facilities, residential, educational, institutional, business as well as public buildings. The objective of this study is to evaluate and determine the vulnerability of existing buildings in seven major areas near Kota Kinabalu district using Rapid Visual Screening (RVS) scoring method based on FEMA154 (2002). The rapid visual score indicates that from the total two-hundredth-fifty (250) buildings assessed, (60.4%) are categorized as unsafe buildings and are strongly recommended for further evaluation and detailed analysis whereby modelling of structure is necessary

ESTIMATION OF PEAK GROUND ACCELERATION OF RANAU BASED ON RECENT EARTQHUAKE DATABASES

The occurrence of earthquake with magnitude MW 6.0 in Ranau recently has triggered many questions regarding their nature of recurrence, characteristics in size and mechanism in and its surrounding region. In recent years, Sabah has witnessed an increase in low to moderate seismic activities due to the causative ground structures which reflected in their seismic productivities. Over the past years between 1900 until recently, magnitudes ranging from MW 2.9 to 6.0 were known to have occurred. While large magnitude earthquakes are fortunately rare, in the history of earthquakes, the region already experienced devastating earthquake including a magnitude of MW 5.8 on 26th July 1976 centred in Lahad Datu. The observation on earthquake catalogue spanning from 1900 to 2014 has been obtained from various earthquake data centers, Ranau previously recorded an earthquake with magnitude MW 5.1, the repeat over intervals of sudden large earthquake is considered to have much shorter recurrence intervals. This paper discusses the procedure for evaluating the probabilistic seismic hazard analysis (PSHA) whereas the peak ground acceleration (PGA) on bedrock of Ranau area for 10% and 2% probability of exceedance is taken into account. By analysing the correlation between the tectonic features and the available data on past seismicity, the estimation of PGA is based on smoothed-gridded seismicity with a subjectively chosen correlation distance of 50 km. The PGA estimation values for Ranau are approximately in the range of 80 to 140 cm/s2 that will be exceeded 10% probability of exceedance and 140 to 250 cm/s2 for 2% probability of exceedance

Seismic hazard curve as dynamic parameters in earthquake building design for Sabah, Malaysia

This paper presents the significance of a seismic hazard curve plot as a dynamic parameter in estimating earthquake-resistant structures. Various cases of structural damages in Malaysia are due to underestimating earthquake loadings since mostly buildings were designed without seismic loads. Sabah is classified as having low to moderate seismic activity due to a few active fault lines. Background point, area, and line sources are the three tectonic features that have impacted Sabah. Data on earthquakes from 1900 to 2021 have been collected by a number of earthquake data centers. The seismicity is based on a list of historical seismicities in the area, which stretches from latitudes 4 ◦S to 8 ◦N and longitudes 115 ◦E to 120 ◦E. The goal of this research is to develop a seismic hazard curve based on a conventional probabilistic seismic hazard analysis being examined for the maximum peak ground acceleration at 10% probability of exceedance as published in MSEN1998-1:2015. This study extended to 5% and 2% probability of exceedance combined with the seismic hazard curve by using Ranau as a case study. To calculate the expected ground motion recurrence, such as peak ground acceleration at the site, earthquake recurrence models were combined with selected ground motion models. A logic tree structure was used to combine simple quantities such as maximum magnitudes and the chosen ground motion models to describe epistemic uncertainty. The result demonstrates that peak ground acceleration values at the bedrock were estimated to be 0.16, 0.21, and 0.28 g of the total seismic hazard curve at 10%, 5%, and 2% PE in a 50-year return period, respectively. The seismic hazard study at a Ranau site basically depends on the seismicity of a region and the consequences of failure in the past. Thus, the results can be used as a basis for benchmarking design or evaluation decisions and for designing remedial measures for Sabah constructions to minimize structural failure

Relationship of Rainfall Intensity with Slope Stability

The impact of rainfall on landslides is not an uncommon issue worldwide, including in Malaysia. It is a major challenge for geotechnical engineers to ensure the constructed slope is safe and can sustain longer periods of time, including during heavy rainfall. Kota Belud, Sabah, has been selected as the study area to meet the study objectives. Heavy rainfall has been recorded every year within Kota Belud, which has caused a repetition of landslide occurrences within the hilly areas, especially during the monsoon season. Presently, there is no local procedure for determining the rainfall intensity value for slope stability analysis. This study utilized the rainfall intensity value from Hydrology Procedure 26. Seepage analysis conducted shows rainwater infiltration has caused the groundwater level to increase from rainfall starts until 0.5 m below ground level and decrease after rainfall stops, creating fluctuations in the groundwater level during the wet and dry conditions within the wetting front. The factor of safety of the slope shows a decreasing trend, with a reduction of around 27 to 33% after 24 hours of rainfall in conjunction with the changes in groundwater level. However, the factor of safety increased by around 3% from the initial condition after 48 hours. The objective of this study is to identify the factor of safety of a rainfall-induced slope within Kota Belud utilizing the rainfall intensity design limits from Hydrology Procedure 26. Doi: 10.28991/CEJ-SP2023-09-06 Full Text: PD

Preliminary vulnerability assessment of existing state public buildings in moderate seismic region at Semporna, Sabah using rapid visual screening method

The Ranau Earthquakes in June 2015, which hit the territory of Sabah, have highlighted the necessity to assess the vulnerability of the existing buildings. A special concern for vulnerability assessments on the existing public buildings in Sabah is also caused by the fact that earthquake design norms have only been enforced in its municipal area since 2015. Most of the existing public buildings in Sabah were designed without seismic resistance. Therefore, engineers are concerned about the seismic vulnerability of public buildings due to the lack of earthquake consideration in building design procedures. This paper presents the vulnerability assessment of public buildings in Semporna due to the earthquake using Rapid Visual Screening (RVS). Eleven (11) public buildings have been selected for the vulnerability study in Semporna, which is classified as a moderate seismicity region in Sabah. The RVS procedure that has been formulated in Federal Emergency Management Agency (FEMA) P-154 is then used to identify, inventory, and rank potentially seismically hazardous buildings. A high score (i.e., above the cut-off score) indicates the adequate seismic resistance of a building, whereas if a building receives a low score, it should be assessed in a detailed analysis by a professional engineer. According to the RVS score results, 91 percent, or ten (10) buildings, have a high potential seismic risk. These results indicate that further detailed assessment of the building is highly recommended

A Geographically Weighted Regression Kriging Approach for Mapping Swelling Potential of Garinono Formation Soil

The Beluran-Telupid road is notoriously known for its deterioration which sits on Garinono Formation soil and is rich with argillaceous melange. This contributed to inconvenience to motorists apart from being perilous when the subgrade of the road starts to degrade. A geographically weighted regression kriging was conducted along the road based on 25 samples to generate a swelling potential map. The results from the samples have reaffirmed the argillaceous nature of the soil due to the high composition of fine grains mainly clay, especially at the midsection. Nevertheless, after computation, most of the soils have medium swelling potential. After geographically weighted regression kriging was conducted, certain areas are defined as areas which have high swelling potential. Methodologies in this study increase the chances to validate swelling potentials and reduce the gap which is missing in the construction industry involving public road and geotechnical projects

Utilization of Micronized Polyethylene Terephthalate (MPET) as a Filler in Asphalt Pavement

Nowadays, plastic pollution is one of the most critical issues related to sustainability development that need to be solved. Studies indicated that addition of certain amount of recycled plastic from Polyethylene Terephthalate (PET) in asphalt mixture has improved the engineering properties such as marshall stability, moisture resistance, rutting and fatigue resistance. However, the main challenge of direct incorporation of recycled plastic in binder is the thermal incompatibility of two phases which are glass transition and melting temperature. Previous research findings indicated that reduction in particles diameter to micro scale would decrease the PET melting point. Hence, this study investigates the potential of micronized PET from recycled plastic bottle as filler in asphalt pavement. Micronization process at laboratory was carried out to determine the appropriate method prior incorporating it into asphalt mixture. The micronized size of PET incorporated at 0%, 4%, 8%, and 12% by weight of filler is then evaluated for its volumetric properties, mechanical, and adhesion properties. The results showed that the volumetric properties of the asphalt were affected by the presence of micronized PET. The mechanical properties in terms of Resilient Modulus and Indirect Tensile Strength showed increment with addition of micronized PET. Similar trend also observed on adhesion properties. Hence, the findings indicated the potential of utilizing the recycled MPET for local road construction

SUITABILITY OF DBELA METHODS AS SEISMIC VULNERABILITY ASSESSMENT FOR BUILDINGS IN KOTA KINABALU, SABAH

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