The Macesnik landslide in N Slovenia was triggered in 1989 above the Solčava village, but it enlarged with time. In 2005, the landslide has been threatening a few residential and farm houses, as well as the panoramic road, and it is only 1000m away from the Savinja River and the village of Solčava. It is 2500m long and up to more than 100m wide with an estimated volume in excess of 2million m3. Its depth is not constant: on average it is 10 to 15m deep, but in the area of the toe, which is retained by a rock outcrop, it reaches the depth of 30 m. The unstable mass consists of water-saturated highly-weathered carboniferous formations. The presently active landslide lies within the fossil landslide which is up to 350m wide and 50m deep with the total volume estimated at 8 to 10 million m3. Since 2000, the landslide has been investigated by 36 boreholes, and 28 of them were equipped with inclinometer casings, which also serve as piezometers. Surface movements have been monitored geodetically in 20 cross sections. This helped to understand the causes and mechanics of the landslide. Therefore, landslide mitigation works were planned rather to reduce the landslide movement so that the resulting damages could be minimized. The construction of mitigation works was made difficult in the 1990s due to intensive landslide movements that could reach up to 50 cm/day with an average of 25 cm/day. Since 2001, surface drainage works in the form of open surface drains have mainly been completed around the circumference of the landslide as the first phase of the mitigation works and they are regularly maintained. As a final mitigation solution, plans have been made to build a combination of subsurface drainage works in the form of deep drains with retaining works in the form of concrete vertical shafts functioning as deep water wells to drain the landslide, and as dowels to stop the landslide movement starting from the slide plane towards its surface. Due to the length of the landslide and its longitudinal geometry it will be divided into several sections, and the mitigation works will be executed consecutively in phases. Such an approach proved effective in the 800m long uppermost section of the landslide, where 3 parallel deep drain trenches (250m long, 8 to 12m deep) were executed in the autumn of 2003. The reduction of the movements in 2004 enabled the construction of two 5m wide and 22m deep reinforced concrete shafts, finished in early 2005. In Slovenia, this sort of support construction, known from road construction, was used for the first time for

Large rock slides frequently cause secondary unstable phenomena. Many such instability processes happened after December 2001, when the Strug rockslide estimated at 95,000 m3 was triggered above the Koseč village near Kobarid in the Julian Alps, W Slovenia. It was initiated at the contact between high permeable calcareous rocks (Cretaceous scaglia) thrusted over nearly impermeable clastic rocks (Cretaceous flysch). Soon after the rockslide initiation, a rock fall with a volume of 45,000 m3 was initiated within the rockslide. The kinetic push of the rock fall caused the movement of a translational soil landslide with a volume of 180,000 m3 that partially slipped into the torrential ravine of the Brusnik Stream. After a sudden drop of 15 m in December 2001, the rockslide average velocity exponentially slowed down to less than 10 m/year till the end of 2002, and came to a practical stillstand in 2003. After the rainfall in spring 2002, small debris flows made of clayey gravels with a volume of up to 1000 m3 started to flow from the zone of accumulation of the rock fall over the soil landslide to and along the channel of the Brusnik Stream. In 2002, more than 20 debris flow events were registered. The statistical analysis of the measured local rainfall intensities showed that debris flows were initiated at daily rainfall reaching from 20 to 30 mm, depending on the antecedent precipitation. This value may be taken as a specific hydrologic threshold for this site. Because in 2003 no more debris flows were registered, a conclusion was drawn that debris flow events were rainfall-induced but governed on the same time by the availability of rock fall debris in its zone of accumulation.

In two events, on November 15 and 17, 2000, near the Mangart Mountain (2679 m a.s.l.), NW Slovenia, two translational landslides (debris flow slides) with a total volume of more than 1.5 million m3 occurred on the Stože slope composed of morainic material filled with silt fraction. The first landslide was associated with a dry and the second landslide with a wet debris-flow, respectively. The rain gauging station in the village of Log pod Mangartom recorded 1638.4 mm of rainfall (more than 60% of the average annual precipitation) in the 48 days before the events (rainfall intensity of 1.42 mm/h in 1152 h). The recorded rainfall depth has a recurrence interval of more than 100 years. Other recorded rainfall depths of shorter duration (481.6 mm in 7 days, 174.0 mm in 24 h, 70 mm in 1 h) have recurrence intervals of much less than 100 years. A hydrological analysis of the event showed that the increase in runoff coefficients during the wet period in autumn 2000 before the landslide was as high as two- to threefold. An analysis using natural isotopes of δ18O and tritium of water samples from the Stože landslide area has shown permanent but slow exfiltration of underground waters from a reservoir in the slope. In the case of low-intensity and long-duration rainfall in autumn 2000, relatively low permeable (10 -7 m/s) morainic material was nearly saturated but remained stable (average porosity 21%, water content 20%, liquid limit 25%) until high artesian pressures up to 100 m developed in the slope by slow exfiltration from the relatively high permeable (10 -5 m/s) massive dolomite. The Stože landslide (two debris flow slides) was triggered by high artesian pressures built in the slope after long-duration rainfall. The devastating debris-flows formed from the landslide masses by infiltration of rainfall and surface runoff into the landslide masses and by their liquefaction.

This landslide was induced by extreme rainfall by the Typhoon 2011-12. It killed 5 residents. Estimated depth of the sliding surface was about 40 m.

During the 2004 Mid-Niigata Prefecture earthquake, thousands of landslides were triggered, among them two large-scale rapid landslides (Higashi Takezawa and Terano landslides) occurred within past landslide masses and dammed the river at the toe of the landslides, posing great risks for the society. Detailed field investigation was performed on these two landslides. To examine the triggering and movement mechanisms, samples were taken from these two landslides. By using a ring shear apparatus, real earthquake wave loading test and cyclic loading tests were performed on these samples. The test results revealed that those sand samples from both landslides can suffer from sliding surface liquefaction phenomenon with very low final apparent friction angles, while the silt sample from Terano landslide showed no liquefaction failure, indicating that the sliding surfaces of these rapid landslides must have been formed within the sand layer in the past landslide masses.

Two debris flows occurred on Kuskonook Creek in British Columbia, Canada, in August and September 2004. The initiation factors included a major forest fire in the catchment in 2003, in association with relatively small rainfall events and the accumulation of sediment in the creek channels since the last large debris flow event. Previous regional studies and morphometric comparisons with other similar catchments indicate that Kuskonook Creek has characteristics predisposed to debris flows, even without the affects of a forest fire. Based on the investigations and analyses, a magnitude/frequency relationship for future debris events on Kuskonook Creek was developed, and this information was used to carry out a partial risk assessment. It is suggested that for design purposes, a 1/50-year return period and the corresponding debris flow magnitude of 15,000 m3 would provide conservative protection to the users of the provincial highway at the mouth of the creek.

Typhoon Morakot caused serious damage to southern Taiwan. Almost all major mountain highways located in the affected region suffered severe damage from landslides, rock falls, and debris flows. Among these highways, Ali Mountain Highway is one of the most severely affected. Ali Mountain Highway, i.e., T18 route, was constructed in the early 1980s. For the past 30 years of operation, it has suffered substantial damage from different natural hazards. The continued damage–rehabilitation cycle is implemented to maintain the serviceability of this highway. Ali Mountain Highway was seriously damaged by the strike of typhoon Morakot on August 8, 2009. Traffic through this highway was interrupted for over 3 months until temporary rehabilitation was completed. This paper provides a summary of the damage suffered along the Ali Mountain Highway and presents suggestions for mitigation strategies to minimize the likelihood of similar levels of damage during other extreme typhoons such as the typhoon Morakot. The manuscript summarizes extensive field surveys and aerial photo analysis carried out by the authors to investigate the mechanisms of typical slope failures along the Ali Mountain Highway. The engineering geology perspectives are emphasized in the analyses. Geological and hydrogeological features for the sites in this study were found to be the most influential factors dominating the failures. The fault-related weak zones and impermeable layers dominated the global stability of the slopes. In summary, geotechnical engineers should consider carefully the characteristics of geological structures for mitigation and rehabilitation of landslides. Extreme scenarios, such as typhoon Morakot, should also be considered. Source: "Typical landslides and related mechanisms in Ali Mountain highway induced by typhoon Morakot: perspectives from engineering geology" Landslides (23 September 2011), pp. 1-16. by Chia-Nan Liu, Jia-Jyun Dong, Chi-Jen Chen, Wei-Fong Lee

A large landslide formed at Maierato (Vibo Valencia District), Southern Italy, on 15 February 2010, at 1430 hours local time, when rapid failure occurred after several days of preliminary movements. The landslide has an area of 0.3 km2, a runout distance of 1.2 km and an estimated volume of about 10 Mm3. The landslide caused nearly 2,300 inhabitants to be evacuated, with high economic losses. The most probable trigger of the landslide was the cumulative precipitation over the preceding 20 days (having a return period of more than 100 years), which followed a long period of 4–5 months of heavy rainfall (of about 150% of the average rainfall of the period). This report presents a summary of our findings pertinent to the landslide’s activities based on our field investigations. In particular, this report covers (1) details of land deformation caused by the landslide, (2) geology pertinent to landslide development, (3) identification of the landslide mechanism and its triggering factors based on the analysis of the boring core specimens and landform features, as well as the available video of the event, and (4) preliminary evaluation of the stability of the original slope before the landslide using the finite element-based shear strength reduction method. The aim of the paper was to describe the landslide and explain its mechanism of occurrence.

The Japanese landslide expert team conducted landslide investigation in and around Machu Picchu citadel since March 2000 in cooperation with the Instituto Nacional de Cultura (INC) and the Instituto Nacional de Recursos Naturales (INRENA). The investigation results and the cooperation scheme between ICL and the Government of Peru are introduced.

A pilot area for landslide monitoring, prediction and early warning program has been established in Banjarnegara Regency, Central Java Province, since year 2007. Based on the site investigation, it is clarified that not only the rain intensity but also the morphology and geological conditions of study area significantly control the occurrence of landslides. The unstable zone in the study area is situated at lower slope of mountains with the slope inclination of 20^o to 60^o. The moving materials consist of colluvial deposits of silty clay overlying the inclined impermeable layer of clay, which is situated at the lower part of the andesitic breccias mountain. The clay layers are inclined at the same direction of the slope (i.e. 85^o) and this becomes the sliding failure for the above colluvial soils. The moving zone is saturated at most of the rainy season due to the lower position of the zone comparing to the surrounding mountainous slopes. The existence of impermeable clay layer underneath the colluvial soils creates the saturation condition within colluvial soil gradually increased and maintained during the rainy season, until then the rise of pore water pressure within this soil induces the movement. Therefore, monitoring of the pore water pressure (groundwater table) in response to the rain infiltration should be the main concern in establishing early warning for the slope movement.

The Asian Joint Research Project for Early Warning of Landslides consisting of International Consortium of Landslide (ICL), Gadjah Mada University (GMU), and Disaster Prevention Research Institute of Kyoto University (DPRI/KU) has conducted a preliminary investigation and established a real-time monitoring and early warning system at that pilot area. The outdoor unit of fieldserver gathers the data from multiple sensors (two long-span extensometers, raingauge, IP camera and water pressure sensor), whereas indoor processing unit will store data on the monitor, and send the data through GPRS modem to be displayed in a webserver.

Karanganyar and the surrounding area are situated in a dynamic volcanic arc region, where landslide frequently occurs during the rainy season. Indeed, the rain-induced landslide disasters have been resulting in 65 fatalities and a substantial socio-economical loss in last December 2007. Again, in early February 2009, 6 more people died, hundreds of people temporary evacuated and tens of houses damaged due to the rain-induced landslide. It was found that weathered andesitic-steep slope (steeper than 30^o) was identified as the highest susceptible slope for rapid landslide, whilst the gentle colluvial slope with inter-stratification of tuffaceous clay-silt was found to be the susceptible slope for creeping. Finally, a programme for landslide risk reduction and control were developed with special emphasize on community-based landslide prevention and early warning system. It should be highlighted that the social approach needs to be properly addressed in order to guarantee the effectiveness of landslide risk reduction.