The effectivity of community-based early warning system on reducing Semeru eruption impact post-eruption 2021

Disaster communication plays an essential role in the disaster risk management phase. In general, this disaster communication can be divided into three, namely: pre-disaster, during the disaster, and post-disaster. Disaster communication in Indonesia has been extensively implemented in various disaster events. Semeru volcano is one of the active volcanoes in Indonesia whose eruption period cannot be predicted with certainty. Hot clouds falling from the Semeru volcano in 2021, which resulted in casualties, loss, and property damage, proves that disaster communication in the Semeru Disaster Prone Area needs to run more effectively. The Early Warning System currently in effect in the Semeru Volcano disaster-prone area comes from several parties, including 1) Semeru Volcano Observation Post, 2) Field Officers of the Lumajang Regency Regional Disaster Management Agency, and the Community in Simbar Semeru in collaboration with Magma ESDM. This study analyzes disaster information and communication effectiveness in the Semeru Volcano Hazardous Area after the 2021 Eruption. Primary data collection was carried out through in-depth interviews and observations. In-depth interviews with each stakeholder responsible for providing information to the public. The study results show that the pre-eruption of Mount Semeru disaster communication in 2021 has yet to be maximized. This is evidenced by the fact that residents still need awareness and preparedness to face the dangers of Semeru Volcano eruptions. Meanwhile, after the Semeru eruption of 2021, the population has been alerting to any increase in Semeru Volcano activity.


Introduction
Many volcanoes characterize the volcanic arc in Indonesia, so the frequency of volcanic eruptions is relatively high with various eruptions [1].One of the most active volcanoes in Indonesia is Semeru.Semeru Volcano is one of the results of the subduction zone between the active Indo-Australian tectonic plate and Eurasia, which causes the eruption type of Semeru Volcano in the form of Vulcanian and Strombolian [2].The combination of the two types of eruptions caused the formation of a scoria cone at the top of Semeru Volcano.In addition, the force of magma from within and avalanches of material from the lava dome also contributed to the considerable impact caused by the volcano's eruption.Recently, Semeru Volcano has been in normal active status or level 1 to the highest level or level 4 [3,4,5].The character of this volcanic eruption is in the form of falling incandescent material, volcanic ash, lahar flows, and material that falls around the crater and forms a lava dome at the summit [6].This makes Semeru grow tall and large because the material is not distributed elsewhere.On the other hand, volcanic activity in the form of eruptions at Semeru Volcano often occurs [3].The lava dome that continues to form becomes unstable, triggered by rainfall.When the dome landslides, the gas in the body of the volcano is pushed out to create a Heat Cloud (Awan Panas Guguran / APG).This Semeru APG has hazardous characteristics, especially in a south-southeast direction in the Pronojiwo District area [7].
It is known that in 2020, the intensity of the eruption of Semeru Volcano increased [3].This condition occurs in a small radius, so the community does not feel the impact of the damage.As a result, the level of public vigilance was reduced because they considered the eruption of Semeru Volcano not dangerous for them.It should be understood that there is a difference between APG produced from lava dome avalanches and eruption hot clouds that directly come from the eruption or eruption process [8].Although eruptions at Semeru Volcano continue, and this is normal, it is crucial to distinguish threats and how to anticipate them.
Instrumentally based on the volcano observation post (PPGA), the eruptive activity of Semeru Volcano is recorded every day, with records of the number of times eruptions occur and the strength of its energy [9].However, sometimes, the eruption of Semeru Volcano is not visually visible, especially when the ejected volcanic material falls around the top of the mountain, and weather conditions could be better.This is a concern because one of the dangers in Semeru is the avalanche of lava domes that form Heat Clouds, as happened in the eruption of December 4, 2021.Even since December 1, 2021, warnings have been given about volcanic ash falling as far as 2,000 meters.The following is a pile of volcanic material after the 2021 eruption based on documentation from PPGA Gunung Sawur [8].In 2021, Semeru Volcano's eruption was tremendous, resulting in the Gladak Perak bridge being cut off and one village being buried by lahar triggered by heavy rain [10].In addition, one of the villages in Pronojiwo also became a lava flow because of its location close to Curah Lengkong [11].This change in the lava's path is unknown to the public, so they assume that the eruption on December 4, 2021, will be similar to eruptions in previous years.Before the eruption period in 2021, it was known that Semeru's volcanic activity showed a not-too-large impact [12].As a result, residents continued their usual activities and even documented the eruption within less than 13 km.Ironically, people are unaware of the dangers and consequences that will be caused, so the explosion in 2021 caused a lot of material losses and casualties.
Based on a survey conducted by the Semeru Volcano Observation Post (PPGA) and several related communities, it is known that information about the status of Semeru Volcano needs to be better informed to the public.In addition, the early warning system still needs to be well-formed, causing residents not to prepare for the disaster that will occur [13,14].
Unlike in 2021, the emergency of Semeru Volcano has changed in 2022.Although the lava path of Semeru Volcano shifted back eastward, the eruption in 2022 caused no casualties [15,16].This is due to improved early warning after a disaster preparedness evaluation in 2021, which still needs to be improved.Increasing awareness of residents and village governments about the importance of the Early Warning System (EWS) at Semeru Volcano helps reduce the risk and impact of volcanic eruptions [17][18][19][20][21]. Therefore, this article will discuss the early warning system in the Disaster-Prone Area III of Semeru Volcano.

Methods
The research method used is a qualitative approach with data collection techniques in the form of observation and interviews.Observations were made in seven hamlets most affected by the eruption on December 4, 2021, namely: 1) Umbulan Hamlet, 2) Sumbersari Hamlet, 3) Sumberwuluh Hamlet, 4) Kajarkuning Hamlet, 5) Curahkobokan Hamlet, 6) Kamar A Hamlet and 7) Gumukmas Hamlet.Data from observations in the area will provide a direct picture of the conditions and impact of disasters experienced by communities at the eruption site.The following is a Map of the Research Location.In addition, the interview method (in-depth interview) is also used to explore more in-depth information from several related parties.Some parties interviewed were the Head of the Semeru Volcano Field Observation Post, representatives from PPGA Semeru located on Mount Sawur Lumajang, and Oro-Oro Ombo Village Stakeholders.Researchers can gain perspectives, knowledge, and experience from those directly involved in pre-disaster handling and recovery, emergency response, and post-eruption disasters by conducting interviews with relevant parties.

Analysis of Early Warning System Aspects
Through an in-depth analysis of the process of building community resilience, it can be concluded that the community and local authorities have fulfilled all the main elements of the early warning system.The four components include knowledge of risk, monitoring and warning services, dissemination and communication, and community response skills [22][23][24][25].In this case, the Disaster Management Capacity of the National Agency for Disaster Management (BNPB), the Center for Volcanology and Geological Hazard Mitigation (CVGHM), and the Regional Agency for Disaster Management (BPBD) have essential roles as authority holders at the national and regional levels.
At the community level, the Community Based Disaster Management Organization (CBDMO) represented by the Lumajang Regency Rapid Reaction Team (TRC PB) and village youth volunteers commanded by the field head of the Semeru Volcano Post in Curah Kobokan, also play an essential role in fulfilling these four elements.This OPBBM has initiated Community-Based Disaster Risk Management (PRBBK) activities in the Semeru Volcano area.Although rarely discussed, the contribution and active role of OPBBM are significant in building community resilience and facing potential disasters in the area.
The eruption of Semeru Volcano in 2022 caused a significant impact in Kajar Kuning Hamlet, Sumberwuluh Village, Candipuro District, and Lumajang District.The damage caused by rain-triggered lahar is almost comparable to the previous year's eruption in 2021, which caused total damage in several hamlets [10,12].Related research articles mention that the eruption resulted in changes in the morphology of the mountain, and the path of the lahar flows shifted from the southeast to the east by several degrees [10].
There is an important note from several research articles and disaster events in the previous year that the development of early warning systems at the foot of Semeru Volcano has increased [10,12,15,16].In its implementation, the early warning system has proven to be more effective in reducing casualties during eruptions.Relevant stakeholders also mentioned that thanks to efforts to update and improve the system, people in disaster management planning for the eruption of affected volcanoes can receive faster and more precise warnings to have a more incredible opportunity to save themselves and take the necessary preventive measures.
Related studies also highlight the importance of learnings from previous year's disaster events in improving future disaster preparedness and mitigation [7,8,12,18,20].With the movement of lahar paths, understanding the changes in mountain morphology and lahar paths that can change over time becomes crucial in planning and implementing early warning systems.

Knowledge of Risk
Systematic data collection and risk assessment results show that hazards and vulnerabilities are well known.The patterns and tendencies of each factor affecting risk have also been identified.In addition, the provision of data and risk mapping has been carried out extensively.The authorities have drawn up a blueprint and set Semeru Volcano as one of the priorities for handling.The Geological Agency and BPBD are responsible for monitoring and research related to these activities.
At the community level, risk assessment efforts, hazard recognition, and factors contributing to risk have been implemented.Meanwhile, various disaster management training, such as emergency response training, school-based disaster management, community-based disaster management, and emergency relief, as well as workshops and preparation of risk mapping and disaster contingency plans, have been carried out within a period.The Center for Volcanology and Geological Hazard Mitigation (CVGHM), and the Regional Agency for Disaster Management (BPBD) work closely with the community in every capacity-building activity to achieve these goals.

Dissemination and Communication
Based on data from the Semeru Volcano Eruption Emergency Response Command Post (Posko Lapangan), the eruption in 2021 in the form of Heat Clouds has caused a considerable impact.At least 51 people died, 169 were injured, 22 were missing, and 45 suffered burns from the eruption.In addition to casualties, the Post also noted that five body parts were found at the affected location.Many fatalities were caused by a poor early warning system in Disaster Prone Areas (KRB) II and III of Semeru Volcano.However, in early 2022, various disaster agencies, village governments, and local communities have been working to improve early warning systems to be more effective in dealing with eruption disasters.
One of the institutions involved in handling geological disaster problems, namely the Volcanology and Geological Hazard Mitigation (CVGHM), developed an Early Warning System (EWS) by reporting visual observations that can be accessed through the magma.co.id website.This visual observation was obtained from the perspective of Simbar Semeru located in Oro-Oro Ombo Village, Pronojiwo District, Lumajang Regency.Through these visual observations, people can see the lava flow that emerges from the top of Semeru Volcano and see the lava flows from the crater and Pyroclastic Density Current (PDC) clearly at a safe distance so as not to pose a risk of damage.Initially, Simbar Semeru was a Ground Camp in a series of hills south of Semeru Volcano.Besides, it became a tourism object and functioned as a visual observation post of Semeru Volcano.
The field team assigned to the Semeru Volcano Field Post consists of the post chief, a former army soldier, BPBD (in case of emergency), and the local community.Their task is to monitor the activities of Semeru Volcano through CCTV installed in 4 strategic locations, including in the construction of waterways in Kajar Kuning and Umbulan, Supiturang Village, Pronojiwo Lumajang.CCTV is also connected to monitors at guard posts scattered in the northwest part of Sumbersari Hamlet, close to the foot of Semeru Volcano.The number of guard posts is still limited, with locations at RT 13 and at RT 14.This guard post is equipped with Wi-Fi and danger sirens.The construction of guard posts in the village was built with community self-help because many people still live in the area, but the risk of danger is quite considerable.The eruption hazard of Semeru Volcano can be divided into primary and secondary hazards.Primary hazards are direct threats from volcanic eruption products, such as lava flows, pyroclastic flows, volcanic gases, and eruptive lahars.Meanwhile, secondary hazards are indirect threats caused by volcanic eruption products, such as lahars and volcanic avalanches.CCTV results from the post are then connected to YouTube CCTV Semeru to inform Semeru Volcano's condition and end mass digitally.Information about Semeru Volcano activities can also be accessed through the PVMBG page (magma.go.id) and from the Semeru Volcano Observation Post located on Gunung Sawur, commonly called Gunung Sawur Post by the local community.The Mount Sawur Post is tasked with inputting data such as Heat Clouds, lava flows, and earthquake tremors.When an emergency occurred, the information was conveyed intensively to the Semeru Volcano field post in Curah Kobokan through Handy Talky (HT).The condition is said to start an emergency when the earthquake tremor reaches 40 vibrations/second.The following is the dissemination of information through the magma.go.id page.So, the update situation from Semeru volcanic activity can be known in real time.
Early warning system (EWS) for volcanoes is one of the important aspects of mitigating volcanic disasters.Especially after the 2021 eruption of Semeru Volcano, which caused major damage, it is important to evaluate the effectiveness of EWS to reduce the impact of disasters in the post-eruption period.magma.id is an important visual data source for understanding volcanic conditions and EWS operations.Visual data from magma.id includes several parameters, namely the status level of Semeru Volcano, seismicity, mountain deformation (inflation or deflation), and the ambient temperature of the crater.
Visual data based on the status level of Semeru Volcano shows the status level of Semeru Volcano, including Alert (Level II) or Alert (Level III) status after the eruption in 2021.This status indicates the potential for further eruptions and provides clues on the vigilance required by the public and authorities.Analysis of this data helps assess whether the level of volcanic status remains stable or fluctuates, which can influence disaster mitigation decisions.Below is the visual display observed from Simbar Semeru on the magma.go.id page.Efforts to improve early warning systems that have been carried out show that appropriate and effective disaster mitigation measures can help communities to prepare for eruptions and reduce disaster risk.Furthermore, increasing public awareness about the importance of following early warnings and evacuation procedures is also key in minimizing the impact of volcanic eruption disasters.By combining technology and local wisdom, the early warning system can be further optimized and become an important part of maintaining the safety of people in areas affected by the eruption of Semeru Volcano.

Conclusions
Disaster communication, especially emergency management, is crucial.In the Semeru emergency in 2021, disaster communication is crucial in the community.Emergencies require a good and clear coordination and command system.If disaster communication is not carried out as soon as possible when the hot cloud falls down the river valley, there will be casualties and property.The early warning system at Semeru Volcano after 2021 has proven to overcome losses due to the 2022 eruption.Disaster communication seeks to integrate between authorized institutions, stakeholders, and the community to create a disaster-preparedness village.