Visualising and experiencing geological flows in Virtual Reality

<p>Resilience to natural hazards depends on a person's ability to envision an event and its consequences. While real life experience is precious, a real event experience is rare, and sometimes fatal. So, virtual reality provides a way to getting that experience more frequently and without the inconvenience of demise. Virtual reality can also enhance an event to make it more visible, as often things happen in bad weather, at night or in other inconvenient moments.</p><p>The 3DTeLC software (an output from an ERASMUS+ project, http://3dtelc.lmv.uca.fr/) can handle high-resolution 3D topographic models and the user can study natural hazard phenomena with geological tools in virtual reality. Topography acquired from drone or plane acquisitions, can be made more accessible to researchers, public and stakeholders. In the virtual environment a person can interact with the scene from the first person, drone or plane point of view and can do geological interpretation at different visualization scales. Immersive and interactive visualization is an efficient communication tool (e.g. Tibaldi et al 2019 – Bulletin of Volcanology DOI: https://dx.doi.org/10.1007/s00445-020-01376-6).</p><p>We have taken the 3DTeLC workflow and integrated a 2.5D flow simulation programme (VOLCFLOW-C). The dynamic outputs from VOLCFLOW-C are superimposed into a single visualization using a new tool developed from scratch, which we call VRVOLC. This coupled visualization adds dynamic and realistic understanding of events like lahars, lava flows, landslides and pyroclastic flows. We present two examples of this, one developed on the Digital Terrain Model of Chachani Volcano, Arequipa Peru, to assist with flood and lahar visualisation (in conjunction with INGEMMET, UNESCO IGCP project 692 Geoheritage for Resilience and Cap 20-25 Clermont Risk). And another with an Icelandic debris slide that occurred in late 2014 possibly related to permafrost degradation (in conjunction with the ANR PERMOLARDS project).</p><p>We thank out 3DTeCL colleagues, without which this would not be possible, and acknowledge financial support for the PERMOLARDS project from French National Research Agency (ANR-19-CE01-0010), and this is part of UNESCO IGCP 692 Geoheritage for Resilience.</p>

Application of GIS-Based Knowledge-Driven and Data-Driven Methods for Debris-Slide Susceptibility Mapping

Debris-slides are fast-moving landslides that occur in the Appalachian region including the Great Smoky Mountains National Park (GRSM). Various knowledge and data-driven approaches using spatial distribution of the past slides and associated factors could be used to estimate the region's debris-slide susceptibility. This study developed two debris-slide susceptibility models for GRSM using knowledge-driven and data-driven methods in GIS. Six debris-slide causing factors (slope curvature, elevation, soil texture, land cover, annual rainfall, and bedrock discontinuity), and 256 known debris-slide locations were used in the analysis. Knowledge-driven weighted overlay and data-driven bivariate frequency ratio analyses were performed. Both models are helpful; however, each come with a set of advantages and disadvantages regarding degree of complexity, time-dependency, and experience of the analyst. The susceptibility maps are useful to the planners, developers, and engineers for maintaining the park's infrastructures and delineating zones for further detailed geo-technical investigation.

Operational Estimation of Landslide Runout: Comparison of Empirical and Numerical Methods

A key point of landslide hazard assessment is the estimation of their runout. Empirical relations linking angle of reach to volume can be used relatively easily, but they are generally associated with large uncertainties as they do not consider the topographic specificity of a given study site. On the contrary, numerical simulations provide more detailed results on the deposits morphology, but their rheological parameters can be difficult to constrain. Simulating all possible values can be time consuming and incompatible with operational requirements of rapid estimations. We propose and compare three operational methods to derive scaling power laws relating the landslide travel distance to the destabilized volume. The first one relies only on empirical relations, the second one on numerical simulations with back-analysis, and the third one combines both approaches. Their efficiency is tested on three case studies: the Samperre cliff collapses in Martinique, Lesser Antilles (0.5 to 4×106 m3), the Frank Slide rock avalanche (36×106 m3) and the Samperre cliff collapses in Martinique, Lesser Antilles (0.5 to 4×106 m3) the Fei Tsui debris slide in Hong Kong (0.014×106 m3). Purely numerical estimations yield the smallest uncertainty, but the uncertainty on rheological parameters is difficult to quantify. Combining numerical and empirical approaches allows to reduce the uncertainty of estimation by up to 50%, in comparison to purely empirical estimations. However, it may also induces a bias in the estimation, though observations always lie in the 95% prediction intervals. We also show that empirical estimations fail to model properly the dependence between volume and travel distance, particularly for small landslides (<20,000 <0.02×106 m3).

Landslide Susceptibility Assessment of Wildfire Burnt Areas through Earth-Observation Techniques and a Machine Learning-Based Approach

Climate change has increased the likelihood of the occurrence of disasters like wildfires, floods, storms, and landslides worldwide in the last years. Weather conditions change continuously and rapidly, and wildfires are occurring repeatedly and diffusing with higher intensity. The burnt catchments are known, in many parts of the world, as one of the main sensitive areas to debris flows characterized by different trigger mechanisms (runoff-initiated and debris slide-initiated debris flow). The large number of studies produced in recent decades has shown how the response of a watershed to precipitation can be extremely variable, depending on several on-site conditions, as well as the characteristics of precipitation duration and intensity. Moreover, the availability of satellite data has significantly improved the ability to identify the areas affected by wildfires, and, even more importantly, to carry out post-fire assessment of burnt areas. Many difficulties have to be faced in attempting to assess landslide risk in burnt areas, which present a higher likelihood of occurrence; in densely populated neighbourhoods, human activities can be the cause of the origin of the fires. The latter is, in fact, one of the main operations used by man to remove vegetation along slopes in an attempt to claim new land for pastures or construction purposes. Regarding the study area, the Camaldoli and Agnano hill (Naples, Italy) fires seem to act as a predisposing factor, while the triggering factor is usually represented by precipitation. Eleven predisposing factors were chosen and estimated according to previous knowledge of the territory and a database consisting of 400 landslides was adopted. The present work aimed to expand the knowledge of the relationship existing between the triggering of landslides and burnt areas through the following phases: (1) Processing of the thematic maps of the burnt areas through band compositions of satellite images; and (2) landslide susceptibility assessment through the application of a new statistical approach (machine learning techniques). The analysis has the scope to support decision makers and local agencies in urban planning and safety monitoring of the environment.

Teknik Rekayasa Lereng untuk Pengelolaan Gerakan Massa Tanah di Dusun Bengle, Desa Dlepih, Kecamatan Tirtomoyo, Kabupaten Wonogiri, Provinsi Jawa Tengah

Gerakan massa tanah terjadi pada tanggal 28 November 2017 di Dusun Bengle, Desa Dlepih, Kecamatan Tirtomoyo, Kabupaten Wonogiri, Provinsi Jawa Tengah. Tujuan dari penelitian ini untuk mengetahui tipe gerakan massa tanah dan mengetahui nilai faktor keamanan pada lereng berdasarkan sifat fisik dan mekanika tanah. Metode yang digunakan dalam pengumpulan data adalah metode survei dan pemetaan lapangan. Teknik pengambilan sampel tanah yaitu purposive sampling ditentukan berdasarkan jarak panjang longsoran. Hasil laboratorium digunakan untuk menghitung kestabilan lereng menggunakan Metode Fellenius. Data pendukung yang diperoleh dengan pemetaan diantaranya kemiringan lereng, ketebalan dan tekstur tanah, penggunaan lahan dan kapasitas infiltrasi kemudian curah hujan diperoleh dari analisis data sekunder. Seluruh data yang diperoleh dianalisis sesuai dengan kondisi rona lingkungan. Tipe gerakan massa tanah di daerah penelitian adalah debris slide. Nilai faktor keamanan lereng diperoleh nilai 0,687 yang termasuk ke dalam klasifikasi tidak stabil. The ground mass movement took place on 28th November 2017 in Bengle Hamlet, Dlepih Village, Tirtomoyo Sub-District, Wonogiri Regency, Central Java Province. The purpose of this study was to determine type of soil mass movements and determine the value of safety factors on slopes based on physical and mechanical properties of the soil. The methods used in collecting the data were survey and field mapping methods. The soil sampling technique used in this study was purposive sampling based on the long of the avalanche distance. The laboratory results were used to calculate slope stability using the Fellenius Method. The Supporting data obtained by mapping were include the slope of land, the soil thickness and texture, land use and infiltration capacity and rainfall obtained from secondary data analysis. All data obtained were analyzed according to environmental conditions. The type of soil mass movement is debris slide. The value of slope safety factor was 0.687 which was included in the unstable classification.

PENATAAN KAWASAN PASCA BENCANA TANAH LONGSOR DI PUNCAK PASS, KECAMATAN CIPANAS, KABUPATEN CIANJUR TANGGAL 28 MARET 2018

Landslides often occur in Indonesia, including in Puncak which is a tourist area. A landslide disaster occurred at Puncak Pass, Cipanas Sub-district, Cianjur District, West Java on Wednesday, March 28, 2018 at around 08.00 PM. Typology of landslides that occur is a debris slide consisting of debris materials such as soil, rocks and large trees, and form a basin such as the shape of a horseshoe on the former landslide. Landslide occurred on the slope of the road and destroyed the hotel building, the park behind the hotel and pine forest. Many factors that influence the occurrence of landslide in Puncak Pass, from the analysis there are three main factors causing the landslide: the topography of the landslide is very steep, the occurrence of heavy rain for several consecutive days before the occurrence of landslides, and the slope which always disrupted the transport load of vehicles on it. Arrangement of landslide areas is very important to re-arrange the sustainable condition of the area against similar landslide disaster in the future. These arrangements are: handling of landslides during emergency response, determining the location of new road development, water and drainage management, cliff strengthening, land management, potentially affected settlements, and landslide disaster management.

Analisis Penyebab Kejadian dan Evaluasi Bencana Tanah Longsor di Desa Banaran, Kecamatan Pulung, Kabupaten Ponorogo, Provinsi Jawa Timur Tanggal 1 April 2017

ABSTRAKBencana tanah longsor di Indonesia semakin sering terjadi dari tahun ke tahun. Bencana tanah longsor telah terjadi di Dusun Tangkil, Desa Banaran, Kecamatan Pulung, Kabupaten Ponorogo, Provinsi Jawa Timur pada tanggal 1 April 2017. Lokasi tanah longsor di Desa Banaran, Kecamatan Pulung, Kabupaten Ponorogo, Jawa Timur, terletak pada zona kerentanan tinggi. Tipologi tanah longsor berupa longsoran bahan rombakan, yang kemudian ke arah bawah (Kali Tangkil) berkembang menjadi tipe aliran bahan rombakan. Faktor-Faktor yang berpengaruh terhadap terjadinya tanah longsor lokasi penelitian adalah: kelerengan, batuan dan tanah, rekahan/retakan batuan, konversi lahan, drainase dan keairan, curah hujan tinggi, dan aktivitas manusia. Dari kesemuanya faktor-faktor tersebut, yang paling dominan dan berpengaruh terhadap tanah longsor adalah: lereng yang curam, soil hasil pelapukan sangat gembur dan tebal, alih fungsi lahan dan curah hujan yang tinggi. Material longsoran tidak terkonsolidasi dengan baik sehingga masih mudah bergerak, dan kemungkinan pembendungan pada Kali Tangkil oleh material longsoran tersebut bisa berpotensi terjadinya banjir bandang. Beberapa permukiman yang berada di saekitar lokasi longsor mempunyai risiko tinggi dan sedang terhadap longsor, sehingga perlu dibangun kesiapsiagaan masyarakat, pembangunan sistem peringatan dini longsor serta untuk jangka panjang adalah relokasi jika memang kondisi semakin parah. Pertanian lahan kering pada lereng-lereng sebaiknya menggunakan pola agroforestry. Kawasan sub DAS berisiko longsor, sebaiknya dikembalikan fungsi lahan sebagai hutan konservasi atau hutan lindung seperti sebelumnya.Kata kunci: longsor, Ponorogo, curam, soil tebal, degradasi lahan, curah hujan tinggi, risikoABSTRACTLandslides in Indonesia are becoming increasingly frequent from year to year. A landslide disaster has occurred in Tangkil, Banaran Village, Pulung Sub-District, Ponorogo District, East Java Province on April 1, 2017. The location of landslides in Banaran Village, Pulung Sub-District, Ponorogo District, East Java, lies in the high vulnerability zone. The landslide typology is a debris slide, which then in the downstream direction (Tangkil River) develop into a type of debris flow. Factors that influence the occurrence of landslides in the study area are: slope, rock and soil, fracture, land conversion, drainage and irrigation, high rainfall, and human activities. Of all the influential factors, the most dominant factors for landslides are: steep slopes, weathered soil is very loose and thick, land conversion, and high rainfall. Landslide material is not well consolidated so that it is still easy to move, and the possibility of damming the Tangkil River by landslide material can potentially cause flash floods. Some settlements located near landslide locations have high and moderate risks of landslides, so community preparedness needs to be built, the establishment of landslide early warning systems and long-term relocation if the condition is getting worse. Dryland farming on slopes should use agroforestry patterns. Sub-watershed areas are at risk of landslides, the land should be restored as conservation forest or protected forest as before.Keywords: landslide, Ponorogo, steep slopes, thick soil, land degradation, high rainfall, risk

Оползневый риск в горных районах

Landslide is a major geological hazard, which poses serious threat to human population and various infrastructures. Landslides occur very often together with other natural disasters such as earthquakes, floods or snow melting and volcanoes that play role of triggering mechanism for landslides. Mountainous areas are vulnerable to landslides and have also been affected by earthquakes. Mountainous and coastal areas are the most affected regions. Landslides cause huge damage in the world and kill many people each year. Paper is devoted to landslides research on the base of risk analysis, assessment, management and reduction concept. Landslide Risk Management is seen as a series of events leading to landslides risk reduction and avoiding. It includes landslides monitoring, landslide forecast, engineering works, slopes strengthen, insurance and others. Paper also considered India, China and Russia case studies including Kolka disaster on 20 September 2002 and other related disasters. Kazbek volcanic center is characterized by the complex interrelationship of various hazardous geological processes. Disasters of 2002 and 2014 caused by icerock fall govern importance of investigation of the area. The network recorded a collapse of the mass of ice and rocks in the region of the Devdorak glacier on May 17, 2014 and the movement of the formed stoneice avalanche. In India, the Himalayas are prone to landslides, particularly n monsoon season, from months of June to October. Various types of landslides occur in Himalayas, including block slumping, debris flow, debris slide, rock fall, rotational slip and slump. Generally landslides are triggered by heavy or prolonged rainfall. Landslides cause severe damage to lives and property while also causing disruption in communication networks and movement of traffic. Оползни представляет собой серьезную геологическую опасность, создающую угрозу для населения и различных объектов инфраструктуры. Оползни часто сопровождают другие стихийные бедствия, такие как землетрясения, наводнения, таяние снега и вулканические процессы, которые играют роль механизма запуска оползней. Горные районы, пострадавшие от землетрясений также уязвимы для оползней. Горные и прибрежные районы являются наиболее пострадавшими регионами. Во всем мире оползни наносят колоссальный ущерб и влекут за собой человеческие жертвы. Статья посвящена исследованию оползней на основе концепции анализа, оценки, управления и снижения рисков. Управление рисками рассматривается как серия мероприятий, ведущих к снижению и предотвращению риска оползней. Они включают в себя мониторинг оползней, прогноз оползней, инженерные работы, укрепление склонов, страхование и др. Рассмотрены примеры исследований Индии, Китая и России, включая Колкинскую катастрофу 20 сентября 2002 года и другие связанные с ней катастрофы. Казбекский вулканический центр характеризуется сложной взаимосвязью различных опасных геологических процессов. Бедствия 2002 и 2014 гг., вызванные падением ледяных скал, определяют важность исследования местности. Сеть зафиксировала обвал массы льда и камней в районе ледника Девдорак 17 мая 2014 года и движение образовавшейся ледовокаменной лавины. В Индии Гималаи подвержены оползням, особенно в сезон муссонов, с июня по октябрь. В Гималаях встречаются различные типы оползней, в том числе оползни блоков, обломки, оползни, обвалы, проскальзывание и спад. Обычно сход оползней вызван сильными или продолжительными осадками. Оползни наносят серьезный социальный ущерб, вызывают сбои в различных сетях и движении транспорта.

Mitigation and Bioengineering Measures for Prevention of the Surbhi Resort Landslide, Mussoorie Hills, Uttarakhand Lesser Himalaya, India

Recent cloud bursts and Glacial Lake Outburst Flood ( GLOF ) in the Uttarakhand Himalaya have triggered catastrophic landslides. Heavy monsoon precipitation lashed Uttarakhand causing devastation and series of new landslides in the region. The Surbhi Resort Landslide is located near the hill station of Mussoorie in Garhwal Himalaya, India, in the Upper Krol Limestone. After intense rain in August 1998, the Krol sedimentary deposits suddenly gave way as a deep-seated landslide, blocking the main Mussoorie-Kemptyartery for 15 days. In 2005, the velocity of the slide was determined to be 4–14 mm/year by previous workers, thus it was still active with a modest intensity. Recently in 2018, during monsoon there was heavy rainfall in the Mussoorie and mud flow in the Kemty Fall area. Huge amounts of quaternary debris are still lying on the slope, another high intensity rainfall or cloud burst in future could trigger another large-scale failure. Based on our recent detailed investigations, following mitigation and bioengineering measures are suggested. To lower the ground water table, a series of horizontal drains should be installed at the base of the crown portion of the slide. This would generate an additional discharge which has to be channeled down Rangaon-ka-Khala, the natural channel, down the slope to the Aglar River flowing in the valley below. To prevent further surface erosion, it is suggested that the Rangaon-ka-Khalamust be bioengineered with shrubs and grasses such as Eriophorum comosum, Saccharum spontanum, Pogonatherum spp. And Wood fordia fruticosa while the surrounding slope must be reforested with Quercus leucotrichophora, Alnus napelensis , Pinus spp.and Cedrus spp. Check dams must be constructed on the entire 3.5 km stretch of the Rangaon-ka-khala to lower the velocity of thewater. This could be done either as gabions or in the form of live fascines of Salix tetrasperma or Dalbergia sissoo. The catchmentarea above the Mussoorie-Kempty road can be expected to collect 60,000 m3 in 24 hours in a 25-years reoccurrence cloud burst. Thus proper drains (0.40 m in dia.) on the inside of the road must be installed. The flow velocity at these extreme events would be 4.8 m/switch is slightly above the recommended value. If this water is allowed to flow down the Rangaon-ka-Khala it will most certainly lead to a major debris slide with a vertical velocity of almost 100 m/s with huge erosive power. For this reason, this discharge should be channeled down in plastic or cement lined pipes, preferably to the west of the Siyagaon Village which is reported as stable rather than in the landslide zone itself. It is concluded that these mitigation measures and bioengineering plantation would certainly help stabilize the Surbhi landslide area to prevent further disaster in future that destroyed the water mills, fields of the surrounding villages and mud flow in popular Kempty Fall area. These measures may also be applicable for the other active landslide zones in the NW(Jammu and Kashmir) and NE ( Darjiling-Sikkim ) Himalaya.