Emerging Seismicity Trends Linked to Catastrophic Landslides Behavior in Sri Lanka

Abstract

Sri Lanka was historically not known to be situated in a seismic hotspot. However, in 2022, the island nation experienced seven earthquakes, and in the past few months of 2023, nine seismic tremors have occurred. This marks a significant increase as typically 2–3 seismic events were reported annually. As the seismic activity in the region gains attention, it becomes imperative to understand how these seismic trends influence the stability of fragment rock slopes and nearby deposits. This paper investigates the emerging seismicity trends on the interpretation of major landslides and understanding catastrophic landslides settings in hill country. The outcomes of this study demonstrates that seismicity around Sri Lanka cannot be no longer ignored in slopes stability and should include seismic hazards assessment. Such approach will ultimately contributing to the development of effective mitigation strategies for enhancing public safety and safeguarding critical infrastructure in seismic-prone areas.

1 Introduction

Seismic activity is an inevitable factor affecting slope stability, particularly in the context of rockslides. Given the increasing frequency of seismic and micro-seismic events in the country (Abayakoon 1996), it has become imperative to comprehend the relationship between seismic activity and rockfall hazards, particularly in the geologically active regions of the mountainous slopes. This study will center on an in-depth evaluation of the most recent seismicity records in Sri Lanka, taking into account both historical data as shown in the Fig. 1 and contemporary trends in mountainous slopes.

Fig. 1

History of most prominent earthquake epicenters in the Indian Ocean (Vitanage 1994 and updated)

Analyzing geological and geographical evidence related to landslides is a key aspect of understanding of any link between seismicity trends in the vicinity. The design of mountainous infrastructure and road development projects is a topic of extensive discussion, particularly when it comes to ensuring stability. This involves considering various factors responsible for detachment from the parent rock, due to extensive saturation potential in joints or foliations, interface friction between intact surfaces (Bhandari et al. 1993), human activities, transportation-induced vibrations, and seismicity-induced trends. However, incidents of this nature were not previously documented as seismic events but rather attributed to extensive periods of rainfall. Nevertheless, recent records have become more intriguing, featuring large boulders rolling downhill slopes, traversing various segments, and ultimately coming to rest on a road without inflicting significant damage to the pavement or the road's alignment during heavy rain, 2016. A similar failure was documented as plenty of boulders descended and rolled on densely forest reserved slope as a result of upland instabilities stemming from natural detachment processes and gravitational forces closer to the periphery of the Randenigala reservoir in 2007, as in Fig. 2. Nevertheless, there was no suitable mechanism in place to confirm whether this behavior was induced by seismic activity, primarily due to the absence of adequate monitoring systems Gunasekara (2000a, b). Interestingly, seismicity in the context of Sri Lanka has been somewhat overlooked, as noted by Vitanage (1994). In line with geological and geophysical analyses, study seeks to uncover potential links between seismic events and rockfall occurrences. By analyzing factors such as the spatial distribution, magnitude, and frequency of seismic events (Fernando and Kulasinghe 1986), this study aims to identify potential future seismic hazards. It emphasizes the importance of including the seismicity factor in the evaluation and design of rockfall incidents while taking into account the recorded seismic activity in Sri Lanka.

Fig. 2

Roakslide was initiated from the upper mountain region of the reserved forest towards the reservoir second largest reservoir of the Randenigala Hydroelectric Power Project (Photo by Gunathilake, A.A.J.K.)

2 Landslides Initiation with Rockslides

The susceptibility to landslides and rockslides varies depending on geological and topographical factors (Sassa et al. 2010). Areas with steep slopes, loose soil, and a history of such events are more prone to them. Landslides and rockslides are natural geological processes that can occur when there is a sudden and rapid movement of rock, soil, and debris down a slope (Herath et al. 2014). One of the major factor of destabilization of fragment and massive rocks can be caused by factor of heavy rainfall, which saturates the soil and reduces its stability, which can lose interfaces strength of rocks and soil or withered surface that disturb the natural balance of slopes. This behavior reflects the sliding-surface liquefaction associated with grain crushing and the collapse of grain fabrics (Sassa et al. 2010). The one major incident was Aranayaka Landslide of large magnitude occurred in Aranayaka Divisional Secretariat on 17-05-2016. This completely buried parts of several villages and killed over 132 people and destroyed a large number of houses. The immediate triggering factor of this landslide was relentless rain for 4 days from 14th to 17th May, 2016. One of the key observation is sudden detachment which might suggest regolith sliding on a bedrock interface, foliation and jointed faces as in the Figs. 3, 4, 5 and 6.

Fig. 3

Initial visit of the ICL-IPL landslide experts at Aranayaka Landslide, Sri Lanka (Photo by Dias, A.A.V.; July 2017)

Fig. 4

Close-up view of the crown of the Aranayaka landslide and rock and rock detachment along the foliation joint (Photo by Dias, A.A.V., July 2017)

Fig. 5

Highly fragmented rock at the crown of the slide (Photo by Dias, A.A.V., July 2017)

Fig. 6

Failure along major rock-slope joint plane (Photo by Dias, A.A.V., July 2017)

The occurrence of interface failures at the crown of the Aranayaka landslide is a significant observation, as it appears to have triggered a much more substantial failure event as shown in the Figs. 5, 6 and 7. Interface failures in landslides typically refer to the separation or sliding of different geological layers or materials within the slope, often at a boundary where there is a change in the composition, structure, or frictional properties of the materials. These interface failures can have profound implications for the overall stability of the slope.

Fig. 7

Implementation structure for project RRLL of the SATREP project (2020–2025)

3 Facilitation from the SATREPS Project for Seismicity Monitoring in Landslides Proven Areas

The National Building Research Organisation (NBRO) of Sri Lanka, in collaboration with the Japan International Cooperation Agency (JICA), has initiated a project titled "Development of Early Warning Technology for Rain-Induced Rapid and Long-Travelling Landslides in Sri Lanka (RRLL)." This project has received funding from the Japanese government through the "Science and Technology Research Partnership for Sustainable Development (SATREPS)" initiative, spanning from 2020 to 2025. As a result of this project, additional capacity has been established for the continuous monitoring of micro-seismicity issues in Sri Lanka. This enhanced capacity includes the installation of nine sets of velocity-type seismometers dedicated to monitoring micro-earthquakes, as listed in Table 1, in addition to the existing acceleration-type seismometers. The SATERP project has garnered substantial technical backing from the Japanese government through JICA, and it has been crafted in partnership with a consortium of state organizations and universities, as depicted in Fig. 7. The project evaluation committee has acknowledged the critical importance of implementing a landslide early warning system, emphasizing the need to monitor the increasing trend in recent seismic activity.

Table 1 Seismograph installation sites for landslide studies within the SATREP Project

4 History of Seismicity and Earthquake in Sri Lanka

Sri Lankan history further reveals a history of significant earthquakes originating in the Indian Ocean, providing a substantial body of scientific evidence to aid in advancing our understanding of potential risk scenarios.

4.1 First Recorded Earthquake in Sri Lanka

Throughout the recent past, Sri Lanka has seen numerous records of both confirmed and unverified earth tremors, dating back nearly 500 years to historical records like the one from 1615. It particularly devastating earthquake in Colombo, resulting in 2,000 deaths and the destruction of Colombo Fort, is well-documented in the National Archive Reports (Vitanage 1994). A section of the western side wall surrounding Colombo Fort collapsed and was braking in to more pieces and reduced to rubble. Additionally, a bastion crumbled, causing the tragic loss of four lives in a nearby house. The earthquake also wrought havoc on a stone bridge, leaving it in ruins. Moreover, deep fissures in the earth emerged as a consequence of the seismic event. According to a historical account reproduced in https://www.lankalibrary.com/geo/portu/earthquake.htm), these fissures reportedly emitted flames and sulfur a reasonable period after failure.

Knowledge of this earthquake is derived from a 4 page pamphlet published in Lisbon in 1616, the contents of which were brought to light by late Fr. S.G. Pereira, SJ a pioneer historian, proficient in several languages, Prof. in Missionology Georgian University Rome. Based on the damage reported in this article the earthquake is estimated to have a maximum moment magnitude of 6.5 (Seneviratne et al. 2020) corresponding to an intensity of eight on Modified Mercalli Scale. The Modified Mercalli Intensity (MMI) estimates the shaking intensity from an earthquake at a specific location by considering its effects on people, objects, and buildings. At high intensities (above MMI 6), earthquake shaking damage buildings.

4.2 Other Historical Records

There are no other verified historical records known to the period from 1615 to 1800 (Seneviratne et al. 2021). However many unverified Newspaper reports are available on earthquakes which occurred in or around Sri Lanka in 1882, 1924, 1938 and 1944. Many epicenter of earthquakes cannot be identified due to lack of data. However, it must have originated most likely in the Indian Ocean with close proximity to Sri Lanka. Table 2 display some unverified records, which, based on historical data, appear reasonable to consider.

Table 2 Reasonably informative but non verified data in seismicity events in Sri Lanka

Information pertaining to the submarine earthquake that occurred between Aceh, Indonesia, and Sri Lanka on December 26, 2004, stands as a devastating Tsunami event in Sri Lankan history. This seismic event resulted from the compression between the Indian and Burmese tectonic plates (Iyengar et al. 1999). Recent scientific findings suggest that the once-unified plate, stretching from India to Australia, has fractured into two distinct plates, thereby creating a new plate boundary (Weissel et al. 1980)—totaling 13 instead of the original 12. The initial seismic eruption, with a magnitude of 8.9, originated near the convergence point of the Australian, Indian, and Burmese plates Research indicates that this region is marked by compression, as the Australian plate undergoes counterclockwise rotation, impinging upon the Indian plate (Weissel et al. 1980). Consequently, this geological shift has activated a region of heightened seismic activity in the South Eastern Indian Ocean. The seismic conditions near Sri Lanka seem to be influenced by the geological events occurring in the western coastal region. Notably, the Mannar rift zone and Comorin ridge, both marked by significant tectonic activity, play a prominent role in shaping the seismic landscape (Seneviratne et al. 2020).

5 Reservoir Induced Seismicity Records

Seismicity issues related to reservoirs are a complex and multifaceted challenge. It is crucial to recognize the potential risks and implement proactive measures to mitigate these risks effectively. Sri Lanka's hydropower reservoirs are not only engineering successes but also vital components of the nation's renewable energy strategy. They not only generate electricity but also facilitate water management, agricultural development, and flood control. The large dams have been constructed under the accelerated Mahaweli development Programme (1980-1990), Kotmale (1982), Victoria (1984), Randenigala (1986), Rantembe (1988), Upper Kotmale reservoirs are situated in the central highland which encompasses major tributaries, agricultural and natural forest mountainous areas of the country. Due to the geological evidence, the presence of well-defined major lineaments (Vitanage 1994) in and around these projects is notable. The impoundment of water in large reservoirs can induce seismic activity in and around the reservoirs due to the incremental stress exerted by the standing water and the prominent lineaments. This can potentially trigger risks for infrastructure, communities, and the environment.

5.1 Micro-Seismicity Recording

The instrumentation and micro-seismic monitoring activity was initiated in 1982 in the Kotmale project area (Vitanage 1981) considering the above geological evidences and issues in and around the large reservoirs. The monitoring of micro-seismic were further extended to Victoria and Randenigala reservoirs by establishing seismicity measuring devices closer to the major reservoirs by the Department of Earthquake Engineering, University of Rookee, India and continuous monitoring was done by the Central engineering Consultancy Bureau (CECB). Observations explored the various aspects of seismicity issues associated with reservoir impounding stages as shown in the Fig. 8, (Vitanage 1994). The weight of water impounded in a reservoir exerts significant stress on the underlying rock and faults. Increased pore pressure in the subsurface due to reservoir filling can reduce the effective stress on existing geological faults, potentially triggering seismic events. No significant records were associated with the seismic induced landslide activity which were expected due to micro seismic nature around the reservoir. Nevertheless, numerous landslides were documented both before and after the impoundment of the Kotmale reservoir. To ensure reservoir safety, it is crucial to implement thorough planning, continuous monitoring, and effective engineering solutions for the community safety. Additionally, raising awareness within the community about emergency preparedness can prove to be a valuable tool in many instances.

Fig. 8

Monitoring of micro-seismic activity at the Victoria and Randenigala hydropower reservoirs were conducted by the Central Engineering Consultancy Bureau (CECB) during 1983 to 2002

6 Emerging Trend of Earthquakes in the Indian Ocean

These historical observations, when combined with recent tremor records, emphasize the critical importance of gaining a scientific understanding of the depth of this issue. Some of the early seismic activity records could not be verified due to inadequate documentation or gaps in data. Consequently, the data presented in Table 1 cannot be effectively utilized for interpretations. Nonetheless, there are several Indian catalogues that comprehensively cover earthquake events in the South Indian region (Menon et al. 2010 and Senavirathna et al.). A study conducted using the Indian catalogue identified reliable data, including historical seismographic records, as depicted in Fig. 9 (source: Seneviratne et al. 2020; https://doi.org/10.4038/engineer.v53i2.7412). This data was used to investigate seismic activity in the region surrounding Sri Lanka, which is bounded by Latitude 0°N–20°N and Longitude 70°E–90°E. According to the recent literature measured earthquake data at Colombo should be available from 1909 to 1992 (Seneviratne et al. 2020). Based on historical newspaper records preserved in the national archives from 1938, it is evident that the seismic event left its mark on nearly every corner of the island (Kularathna, et al. 2015). Despite the undeniable sense of alarm and unease caused by the tremors, it is noteworthy that the region's preparedness and resilience were able to prevent any loss of life or significant harm to infrastructure and property. In the southwest, where the tremors were most strongly felt, communities came together to share their experiences and support one another during this unexpected event. The impact on the up-country areas, added a unique dimension to the narrative, as residents in these highland regions also felt the ground shake beneath their feet (Vitanage 1995).

Fig. 9

Epicenters from recent earthquakes (source: Seneviratne et al. 2020) https://doi.org/10.4038/engineer.v53i2.7412)

7 Discussion on Regional Effects

The Indian Ocean region is highly seismically active due to the complex interactions of tectonic plates. The primary plate boundaries in this area are the Indo-Australian Plate to the south and the Eurasian Plate to the north, resulting in frequent seismic activity. As indicated early, Subduction zones are particularly significant in the Indian Ocean region. The Indo-Australian Plate is subducting beneath the Eurasian Plate to the north of Sri Lanka, creating a convergent boundary known as the Sunda Megathrust. This subduction zone is a major source of earthquakes and tsunamis in the region. The Indian Ocean has experienced several devastating earthquakes in its history. One of the most significant was the 2004 Indian Ocean earthquake and tsunami, which had its epicenter off the west coast of northern Sumatra, Indonesia (Parsons et al. 2021). This event caused widespread destruction across the Indian Ocean region, including Sri Lanka: While not located directly on a plate boundary, Sri Lanka is still vulnerable to earthquakes due to its proximity to the subduction zone. The increasingly oblique convergence moving northwest is accommodated by crustal seismicity along several transform and normal faults, including the Sumatra Fault. Deformation related to plate boundaries is not solely confined to the subduction zone (Dissanayake, 2005) and the overriding plate. In fact, the Indo-Australian plate is composed of two somewhat distinct plates, India and Australia, which are connected through a wide and actively deforming region. This region generates seismic activity extending several hundred kilometers to the west of the trench (Hayes et al. 2013). This deformation is exemplified by the recent earthquake sequence in April 2012, which included the strike-slip events of magnitude 8.6 and 8.2 on April 11, along with their subsequent aftershocks. Sri Lanka, as an island nation, has previously encountered moderate to strong earthquakes, and it remains susceptible to more significant seismic events in the future.

In summary, the historical records from 1938 provide us with valuable insights into the island's ability to withstand and recover from seismic events, while highlighting the shared experiences of those who lived through this significant event, particularly in the southwest and up-country areas. Various agencies and research institutions actively monitor seismic activity in the Indian Ocean, including the Indian National Centre for Ocean Information Services (INCOIS) and the United States Geological Survey (USGS). These organizations provide valuable data for earthquake prediction and risk assessment.

8 Recent Development of Seismicity Monitoring

The Geological Survey and Mines Bureau (GSMB) installed three seismometers at different places and also in year 2000 and 2010. The first was placed in Pallekele (PALK) in 2000 and connected to the Global Seismographic Network (GSN). The remaining two were set up in 2010, one in Mahakandarawa (MALK) and the other in Hakmana (HALK), both linked to the GEOFON Network. Access to waveform data and earthquake parameters recorded by these seismometers is available through the internet via the GSN and GEOFON networks, facilitated by GSMB. Therefore, Sri Lankan seismograph network currently has four permanent seismographs:

• 1. PALK (a 90 m deep borehole station with minimal ambient noise) in Pallekale,

• 2. Kandy; MALK in Mihintale,

• 3. Anuradhapura; HALK in Hakmana, Matara;

• 4. BULK in Buddangala, Batticaloa

Further the records obtained from stations in Sri Lanka indicate the seismic activities in closer to some of the major irrigation and water reservoirs as recorded in the Table 3 recorded as at 15.09.18, according to the GSMB.

Table 3 Recently reported seismic events within Sri Lanka

These results shed light on the identification of 14 previously undocumented seismic events see the Table 4, that have occurred over the course of the past 7 months, the year 2023 in the Fig. 10. The recent observation regarding the tremor that occurred in April approximately 26 km off the coast of Hambantota at a 4.4(M_L) magnitude on the Richter scale was that it could have been an aftershock of the major earthquake that occurred in Indonesia. When a major earthquake takes place on an adjacent tectonic plate, it is possible for some of that stress to pass to the neighbouring plates. Notably, the events reached a magnitude of 4.4 (M_L) on the Richter scale, indicating a substantial seismic disturbance. Furthermore, the analysis reveals that three of these recorded events were of significant magnitude, each registering at or above Richter 3.5 (M_L). This underscores the importance of ongoing monitoring efforts (Thaldena et al. 2013) and the need for a robust early warning system to address seismic activity in the region effectively. These findings serve as a stark reminder of the dynamic and potentially hazardous geological conditions in the area, emphasizing the importance of continued research and preparedness to mitigate the impact of seismic events.

Table 4 Rigorously verified data obtained from the Geological Survey and Mines Bureau (GSMB) on seismicity records for the period from January 2023 to July 2023

Fig. 10

Red squire indicates the most recent occurrences of earthquake records within the period of January 2023 to July 2023)

9 Micro-Seismicity Impact on Catastrophic Landslides

Micro-seismic events generate stress waves within the subsurface. These waves can redistribute stress along pre-existing geological interfaces, including the contact between soil and rock. In soil mechanics, effective stress is a critical concept. It's the stress that actually influences the behavior of soil and rock. When micro-seismic events occur, they can momentarily increase or decrease effective stress along the soil-rock interface (Cooray 1994). This can lead to changes in the frictional resistance at the interface. Micro-seismic events can also affect pore pressure within the soil or rock mass. An increase in pore pressure can reduce effective stress, making the interface less stable and more prone to sliding. Repeated micro-seismic events can cause cumulative damage along the interface, weakening the cohesion and frictional resistance between the soil and rock. During the fifth International Symposium on Landslides (Sassa 1988), a special lecture titled "Geotechnical Modeling for Landslide Motion" aimed to replicate the Ontake landslide, which was initiated by the 1984 Naganoken–Seibu Earthquake (Sassa et al. 2010). This landslide involved a massive volume of 36 million cubic meters of material traveling over a distance exceeding 10 km through torrents. It is worth noting that micro-seismicity, referring to the occurrence of small-scale seismic events that are often imperceptible to humans, can indeed influence the reduction of friction at the interface between soil and rock. Recent finding noted that landslides may be triggered by earthquakes and both effects of earthquakes and pore water pressure. The border between rapid landslide and no movement was examined by earthquake loading in addition to pore pressure ratio. The preliminary test proved that the pore pressure ratio ru=0.4 does not cause landslide without earthquake loading though ru=0.5 will cause a rapid landslide (Sassa et al. 2010). Therefore, evaluation of potential catastrophic landslide behavior conditions to be reasonable to consider the micro-seismic impact and understand its sensitivity and missing parameters during prediction slope stability. The various guidelines are thoroughly discuss such matter in evaluation and prediction of the stability potential of rock slopes. The latest confirmed seismic activity data for Sri Lanka can be found in Table 3 and overall verified records within Indian ocean from 1944 to July 2023 as shown in the Fig. 11.

Fig. 11

Earthquakes epicenters of regional events reported around in Indian Ocean Sri Lanka, period of 1944.02.29 to 2023.07.01 in white color rounds (Data Source: United State Geological Survey); Orange and Red color indicates epicenters within and closer to Sri Lanka (Geological Survey and Mines Bureau)

10 Stability Evaluations

The seismic ground acceleration coefficient plays a critical role in the evaluation of stability for various structures and geotechnical applications (Kodagoda et al. 2018). However, it also comes with certain limitations. Seismic ground acceleration coefficients are crucial in assessing the seismic hazard at a particular location. This information is used for urban planning and building code development to ensure structures are designed to withstand potential earthquakes.

As our awareness of micro-seismicity grows, it becomes increasingly vital to incorporate safe seismic coefficients into the evaluation and design of structures. Doing so ensures the safety of people, minimizes long-term risks, and protects against economic and environmental consequences. Moreover, adhering to updated building codes and regulations that consider safe seismic coefficients is not just a legal obligation but a moral imperative. In a world where seismic events can have far-reaching consequences, the consideration of safe seismic coefficients is a cornerstone of resilient and responsible infrastructure development. Many countries have seismic design codes that require engineers to consider these coefficients when designing structures. Compliance with these codes is essential for safety.

11 Seismic Coefficients According to Eurocode 8

This presents a summarized description of the seismic coefficients to be used in slope stability analyses, according to Eurocode 8 (EN 1998-1: 2004; EN 1998-5:2004). The horizontal seismic coefficient is given by the following equation (Eurocode (EC8)(2005):

$$ {k}_h=0.5\left(\frac{a_g}{g}\right)S\;{S}_T $$

Where:

• a_g represents the design value of (horizontal) seismic acceleration on a type A ground, which results from the product between maximum reference acceleration, a_gR, and an importance factor. Definition of the type of ground is recognized as

  • A - Rock.

  • B - Ground Very dense sand or gravel or very stiff clay.

  • C - Dense sand or gravel or stiff clay.

  • D - Loose to medium cohesionless soil or soft.

• g is the acceleration due to gravity;

• S is the coefficient that takes into account the possible amplification of acceleration between the bedrock and the ground surface;

• S_T is the topographic amplification factor greater than 1.0 over or near cliffs, slopes longer than 30 m, and inclinations greater than 15°.

The calculation of a_g and S has been functioned with the topographic effects being particularly relevant in shallow landslides. The values of S_T are shown in Table 5 with the topographic effects being particularly relevant in shallow landslides. In deep landslides, in which the failure surface passes through the toe of the slope, the topographic effect can be ignored, as the seismic amplification factor decreases rapidly with depth. The vertical seismic coefficient is given by the following eqs. (NP EN 1998-5: 2004):

$$ {k}_v=\pm 0.5{k}_h\mathrm{if}\frac{a_{vg}}{a_g}>0.6 $$

$$ {k}_v=\pm 0.33{k}_h\mathrm{if}\frac{a_{vg}}{a_g}\le 0.6 $$

It’s important to note that Eurocode 8 is a complex standard, and its application to slope stability analyses requires a thorough understanding of geotechnical engineering principles and seismic design considerations (Open Source 2023). Engineers, geotechnical specialists and geologists should carefully study the specific sections of Eurocode 8 relevant to their project and seek guidance from experienced professionals when conducting slope stability analyses in seismic-prone areas.

Table 5 Values of the topographic amplification factor, S_r (adapted from EN 1998-5:2004)

Notes

• In the presence of a loose surface layer, the values of the three lines above should be increased by at least 20%.

• The value of S_T may be assumed to decrease as a linear function of the height above the cliff or ridge, and to be unity at the base.

12 Conclusions

In recent years, our understanding of increasing trends in seismic activity has significantly evolved, and we are more aware than ever of the presence and impact of micro-seismicity—small-scale seismic events that were previously unnoticed or underestimated. This new knowledge has highlighted the critical importance of considering safe seismic coefficients in the evaluation and design of slope stability, infrastructure, and buildings. In this article, we will explore why it is imperative to account for safe seismic coefficients, especially in the face of increasing trends in micro-seismicity.

Sri Lanka faces diverse terrain and evolving environmental factors. Continued research and tailored strategies are vital to safeguarding lives, infrastructure, and the natural environment from the potentially devastating impacts of catastrophic landslide behavior. The study on the impacts of emerging seismicity trends on mountainous slope stability interpretation in Sri Lanka underscores the critical importance of considering evolving seismic factors in geological assessments and hazard mitigation efforts.

As seismic events continue to evolve and pose new challenges, it is imperative to adapt our methodologies and strategies to ensure the safety and resilience of the region’s landscapes and communities in the face of these dynamic geological phenomena. Monitoring of micro-seismic activity and earthquake occurrences has been enhanced, and we are now focusing on understanding the potential impacts of micro-seismic activity on rain-induced landslides and rockslides.