Journal of Applied Geology
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DEVELOPMENT OF A NON-EXPERT TOOL FOR SITE-SPECIFIC EVALUATION OF LANDSLIDE SUSCEPTIBILITY
Get PDFThe development of simplified procedure for evaluating susceptibility of slope to rainfall induced, shallow-depth landslides is presented. The procedure is based on the concept that for extended slopes, the shear strength of the slope material should be greater than the applied load on the slope. The concept is extended to include all types of slope materials including rocks and intermediate geomaterials by developing an empirical shear strength rating system. The proposed system does not require expensive and sophisticated laboratory or in situ field tests and can be performed using improvised tools for estimating slope angle and material strength. This approach makes it suitable for preliminary landslide susceptibility screening by non-experts. A system of empirical weighting factors to take into consideration the effects of vegetation, prior slope failures and ground deformation, land use, drainage and artesian flow are presented. Comparison of the proposed procedure with existing procedures for estimating landslide susceptibility shows good agreement in results.
Keywords: Landslide, slope stability, risk rating, land use plannin
EARTHQUAKE DISASTER MITIGATION USING INNOVATIVE RETROFITTING METHOD
Get PDFThe Philippines, because of its geographic location, has been battling the onslaught of natural hazards. About 20 tropical cyclones visit the country every year, active volcanoes erupt within few decades, and earthquakes frequent the country causing damages to structures. Field studies have reported that the casualties and damages due to strong earthquakes have been attributed mainly to collapse of civil engineering structures. Therefore, in order to guarantee the safety of the general public in the event of future earthquakes, it is necessary to study the mechanisms of collapse of these built structures and to provide ways to identify their weak points for the benefit of retrofitting. To address the above issues, a new methodology was developed for the seismic performance assessment of structures. This methodology identifies local failures such as column buckling and connection fracture, which may induce the global system to collapse. In this study, a three-dimensional rigid body-spring method, which can describe the inelastic behavior of a structure and simulate the progressive collapse process, was employed. The sequence of the analysis and results in the form of computer animations offer a real-time assessment of the structural integrity of buildings during earthquakes.
Keywords: Collapse, damage, buildings, rigid body-spring method, simulatio
Promoting a Model of Research-Based Education in Disaster Mitigation
Get PDFThis paper highlights the importance to provide appropriate education model with multidisciplinary approach for supporting the capacity development in disaster mitigation. This education model is implemented as a student community service program, in order to accommodate the needs for improving the students’ knowledge and skill, as well as for stimulating the development of ethical values with respect to humanity and sustainable development concerns. This education model has been conducting as a part of the formal curricula at Gadjah Mada University, and it is accordingly introduced and reviewed in this paper with the specific emphasize to discuss its objective, mechanism, benefits, and social impacts, as well as the respective challenges. Finally, this research-based education model is proposed as one model for the disaster mitigation education, which can be applied not only for Indonesian but may also for ASEAN education model.
Keywords: Education model, research-based, disaster mitigatio
ESTIMATION OF SEISMICALLY-INDUCED POTENTIAL TSUNAMI PENETRATION ONTO COASTAL TERRAINS
Get PDFThis paper presents a methodology of estimating the inland incursion of tsunamis generated offshore by earthquakes by adapting prognostic equations of wind wave run-up to the earthquakes’ long-period characteristics. Tsunami height is estimated from site-specific historical events. The methodology takes account the nearshore depths, backshore topography, tidal range, and tsunami approach direction. Two project applications are discussed; one involving site development planning for a coastal resort whereas the other involving tsunami evacuation zone assessment for a prospective seaport site.
Keywords: Tsunami, run-up, earthquake, planning, site developmen
LOCAL SITE RESPONSE ON SIMULATED STRONG EARTHQUAKE MOTION AT LAEM CHABANG PORT, THAILAND
Get PDFLaem Chabang port, located in Chonburi province in the upper Gulf of Thailand, is similar to many of the ports around the world. Some areas of Leam Cha bang port were layered by backfill materials which are highly suspected to soil liquefaction phenomena from the moderate to strong earthquakes. After one of the world’s largest earthquakes of December 26th, 2004 (Magnitude 9.1) occurred in the region off the west coast of northern Sumatra, various existing active faults have been reported to have more potential to generate future earthquakes. Among those active faults, Ranong and Khlong Marui fault zone, distributed around the south and the upper Gulf of Thailand, have been evidenced to have more seismic activities than December 2004. The closet distance between Leam Chabang port and the extension of Ranong fault zone to the upper Gulf of Thailand is approximately 180-200 km. Though not too close, it is still probable to generate strong earthquakes. This study, for that reason, aims to investigate the local site responses of the filled area at Laem Chabang port due to afresh seismic Ranong active fault by employing the equivalent linear ground response analysis. The complete strong earthquake motion time history from the Ranong fault would be synthetically generated and inputted as a bedrock motion underneath the site of interest. The simplified analysis of liquefaction potential assessment based on the results from local site response would be additionally adopted to evaluate the liquefaction susceptibility around this site. The simulation results indicated that some backfill soil layers which have the very low SPT N-value were significantly suspected to liquefy under strong earthquake motions.
Keywords: Local site response, synthetic accelerogram, liquefaction potential, backfill, Laem Chabang por
Identification of Paleovolcanic Centers in the Bima District, East Sumbawa Island (Indonesia) as Guidance for Future Exploration of Cu-Au Deposits
Get PDFThe formation of Cu-Au mineralization, such as porphyry and epithermal deposits, is strongly associated with volcanic processes in specific tectonic settings, such as subduction zones. The identification of the presence of ancient volcanoes is one of the important steps to finding mineral deposits. This study aims to identify the presence of ancient volcanoes in the Bima District, eastern part of Sumbawa Island, as a step toward determining the potential indication of Cu-Au mineralization. The methods used in this research consist of a literature study, image analysis and remote sensing, field survey and data collection, and petrographic analysis. Image analysis using DEMNAS (Digital Elevation Model), including texture and pattern analysis using the concept of volcanic anatomy, aims to identify the remaining forms of ancient volcanoes. Field surveys and data collection include volcano geomorphology, lithology and sampling, and also geological structures. Petrographic analysis is conducted to qualitatively characterize the texture, structure, and mineralogy of volcanic rocks. The identification results show that there are at least ten volcanoes (crown) identified through image analysis, namely Doro Mbangga, Doro Baku, Doro Donggo Masa, Doro Rompo, Doro Sape, Doro Kowo, Doro Jia, Doro Sambori, Doro Mangge, and Doro Lambu. Each of these volcanoes has one or more eruption center (hummock). The eruption center identified in the central, proximal, to distal facies of the volcano, even superimposing one volcano product with another, and spread around 80-90% in the study area. The volcanic facies in the study area are characterized by the central part being composed of lithologies such as intrusive rocks, lava, and diatreme breccia, while the proximal and distal facies are composed of breccia, volcanic breccia, and tuff. Hydrothermal alteration zones are identified in the central and proximal facies of the volcano. These alterations were associated with the presence of eruption centers, where the abundance of eruption centers means that hydrothermal alterations are particularly well developed and pervasively formed. Identified argillic and advanced argillic alteration associated with stockworks forming a lithocap environment. In addition, the presence of intrusive rocks such as diorite and dacite with chloritic and sericitic alteration in the central facies of Doro Baku can be associated with the presence of deposits such as porphyry and epithermal, so the identification of ancient volcanic eruption centers in the Bima district has implications for the potential discovery of Cu-Au mineralization, such as porphyry and epithermal deposits
EVALUATION OF ROCKFALL OCCURRENCE IN PADANG–BUKITTINGGI ROAD,WEST SUMATRA, INDONESIA
Get PDFA big earthquake occurred on September 20, 2009 in Padang, West Sumatra, Indonesia. This earthquake caused damage and loss of both property and lives. The earthquake also triggered the emergence of rock falls in several areas in Padang, especially in the road of Padang to Bukitinggi. After the earthquake in September, several big rockfalls occurred more than three times that cost lives. Based on field investigations, the incidence of rock falls was caused by field conditions which was prone to rockfall, such as steep slope and exposure of rocks to intensive structures that then triggered by earthquake and rainfall. Therefore, fast action is needed to be taken in order to minimize the impact of the rockfall disaster.
Keywords: Rockfall, slope, rock structure, earthquake, rainfal
Evaluation of Reservoir Characteristics of Wells X, Y, Z in the Pliocene Interval of the Tarakan Sub-Basin, Tarakan Basin, North Kalimantan
Get PDFThe Tarakan Basin is one of the basins that has been producing hydrocarbons since 1901, with nine active oil fields to this day. The exploration of oil and gas in the Tarakan Basin has been ongoing for a considerable amount of time and can be considered as the oldest exploration in Indonesia that continues due to its estimated economically viable reserves based on its geological conditions. Research on the evaluation of reservoir characteristics in the Tarakan Sub-Basin with a Pliocene age interval aims to determine the subsurface lithology and fluid conditions qualitatively and the quantitative characteristics of the reservoir rocks. This study utilizes quantitative petrophysical analysis using a deterministic method with primary data consisting of wireline log data, as well as secondary data including core data, mud logs, biostratigraphy data, drill stem test data, and sidewall core data. Based on the analysis results, the petrophysical properties of the target reservoir in the study area include an average shale volume (VSH) of 16.65% - 29.31%, average effective porosity (PHIE) of 11.80% - 27.09%, which falls into the categories of fair to excellent quality, hydrocarbon saturation ranging from 7.68% - 43.03%, an average permeability value (PERM) of 10.03 mD - 613.29 mD, falling into the categories of good to very good, and a net pay thickness ranging from 4 feet to 16.7 feet, with a total thickness of 67.4 feet containing oil and gas fluids
THE GEO-DISASTER MITIGATION MEASURES IN MYANMAR
Get PDFMyanmar has frequent geological disasters including earthquakes, tsunamis, landslides, and subsidences in karst area. Myanmar indeed is an earthquake-prone area as it lies in one of the two main earthquake belts of the world, known as the Alpide Belt that extends from the Mediterranean through Turkey, Iran, Afghanistan the Himalayas and Myanmar to finally Indonesia. Therefore, Myanmar is vulnerable to hazards from moderate and large magnitude earthquakes, including tsunami hazards along its long coastal areas.
The seismotectonics of the region indicate that earthquakes in Myanmar mostly originates along an active subduction zone (Andaman Megathrust Zone) in the West and along a large active transform fault zone (Sagaing Fault Zone) in the middle part of the country. Local historic records and legends also confirmed the fact that intermittent jerks along these major active faults have caused the majority of earthquakes in Myanmar. These seismotectonic processes are still going on. Along these fault zones stand many large urban cities where thick populations live in. Liquefaction is a very considerable factor according to the past events in the water saturated area near the fault zones.
Geomorphologically, Myanmar has two mountainous provinces: namely, the Western Ranges and the Eastern Highland. These provinces have inherently unstable nature among the areas of the country. The steep slopes, unstable geologic conditions and heavy rains combine together to make the mountainous regions one of the most hazard-prone areas in Myanmar. Landslides frequently happens in these regions, disturbing the connection roads and infrastructures rather than rural houses. Moreover, there has been an increase in human settlement in hazard-prone areas as a result of rapid population growth, as well as improvement in accessibility by road and the onset of other infrastructure development. Consequently, natural and man-made disasters are on the increase and each event affects people more than before. Even in central low land between the two mountainous ranges, landslide features occur along the bank of Ayeyarwady River and its tributaries.
There were also records of moderate tsunami generated by two large magnitude earthquakes, which originated in the Andaman-Nicobar Islands. Of course, the tsunami generated by the giant 2004 Sumatra Earthquake also caused moderate causalities in some parts of the Myanmar coast. Thus, it is evident that Myanmar is vulnerable to disaster from moderate and large tsunamis along its long coastal line.
To mitigate loss of lives and damages of properties, the Natural Disaster Mitigation Committee of Myanmar has been formed since 2004. Moreover, Seismic Hazard Zonation Map of Myanmar has already been prepared with the collaboration of engineering geologists, geoscientists and engineers since 2006. During the year of 2006 to 2008, the Myanmar Geosciences Society (MGS) in collaboration with MEC has prepared the preliminary deterministic seismic zonation maps for four seismically hazardous cities.
Although modern seismological instruments and technical improvement are very essential, earthquake resistant design code shall be enhanced by the cooperative works among the scientists and engineers from various organizations. Landslide potential map and tsunami inundation map are going to be established this year. Moreover, to increase the awareness of the geo-disaster, education and knowledge have been given to those who live in hazardous-prone areas by the collaboration of DMH, RRD, MES, MGS, ADPC and Universities in Yangon. Besides, landslide mitigation technology applied in Myanmar and construction of tsunami shelter in coastal areas are also discussed in this paper.
Keywords: Earthquake, tsunamis, active fault, landslide, liquefactio
SELECTING RELOCATION OF LAND USE IN HOT MUD DISASTER AREA BY APPLYING GEO-ENVIRONMENTAL EVALUATION. CASE STUDY: SIDOARJO, EAST JAVA, INDONESIA
Get PDFSince May 29, 2006, a sea of hot mud has been gushing from the ground in Sidoarjo, East Java, 35 kilometers south of Indonesia’s second largest city, Surabaya. Due to this disaster, approximately thousand of people have been forced from their homes because 600 ha of land and villages were submerged, farmland was ruined, businesses and schools closed as the mud inundated the surrounding area. Relocation of the land uses and supporting infrastructures are become important to support the human survivability and environmental sustainability in this disaster area. In order to select the suitable location for land uses and infrastructures, aspect of environmental geology must be concerned. Geo-Environmental parameters such as geological hazards and geological resources are used to select the suitable relocation area. Evaluation of the suitable land uses is conducted by applying simple overlay rating method. Result of this evaluation shows that the relocation of the land uses can be differentiated into three categories; (i) high risk land use/infrastructure, moderate risk land use/infrastructure and low risk land use/infrastructure. Each of these categories have difference map of relocation suitability, however all maps indicate that the suitable relocation area is in the west-part from the hot mud disaster area.
Keywords: Hot mud blast, relocation of land uses, geo-environmental evaluatio