Tomographic Imaging of the Agung-Batur Volcano Complex, Bali, Indonesia, From the Ambient Seismic Noise Field

The Agung-Batur Volcanic Complex (ABVC), part of the Sunda volcanic arc, is the source of some of the most hazardous volcanic activity in Indonesia. The ABVC has undergone many small (VEI 1-2) eruptions since historical records began in the early 19th century, but Mt. Agung has experienced much larger (VEI 5) eruptions, both in the modern (1963) and historical (1843) eras, as well as several times during the past 2000-3000 years. The 1963 eruption caused more than 1000 deaths, and a more recent eruption in 2017 caused the evacuation of 140,000 people. Delineating the magma structure beneath ABVC is an important first step in understanding the physics of these eruptions. This paper presents the first local-scale study of Rayleigh wave group velocity structure and the seismic velocity structure beneath the ABVC using ambient seismic noise tomography. Seismic data were collected using 25 seismometers deployed across the ABVC during early January to March 2019. The local seismic network provides good resolution beneath both Mt. Agung and Mt. Batur. We obtained 158 Rayleigh Green's Functions, extracted by cross correlating noise simultaneously recorded at available station pairs. We used sub-space inversion to calculate group velocity at different periods and to estimate the lateral variations in group velocity for given periods. 2-D tomographic maps obtained from the inversion of the group velocity of Rayleigh waves clearly showed some pronounced velocity anomalies beneath the ABVC. We applied the Neighbourhood Algorithm (NA) technique to invert the Rayleigh wave dispersion curves to obtain shear wave velocity (Vs) vs. depth profiles. These profiles indicate a low Vs of about 1 km/s underlying the volcanic complex between Mt. Agung and Mt. Batur at depths up to 2 km, which we suggest is due to a combination of low-Vs volcanic deposits as well as a shallow hydrothermal fluids system associated with magma fluids and/or gases produced by magma intrusion at depths >7 km.This work was supported by the USAID’s PEER (Partnership for Enhance Engagement in Research) program with agreement number AID-OAA-A-11-00012, partially supported by P3MI of Global Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Bandung Institute of Technology 2019 awarded to ZZ. 20 of the instrument sets used in the Agung Seismic Experiment were from the Australia-Indonesia Tectonics Observatory, funded by the Australian National University Major Equipment Committee Grant 17MEC33

Management of Facilities and Infrastructure in Improving The Quality of Islamic Education

This article aims to describe the implementation of infrastructure management in improving the quality of Islamic education in Madrasahs. This article uses descriptive qualitative research methods to obtain findings and information related to infrastructure management at MTs Ponpes Al-Iman Muntilan. The purpose of the study was to describe the management of facilities and infrastructure carried out at MTs Ponpes Al-Iman Muntilan, as a madrasa based in Islamic boarding schools. From this research, the following findings were obtained; In the management of the maintenance of facilities and infrastructure, MTs Ponpes Al-Iman Muntilan not only submits to certain teachers or special officers but also involves students directly to practice independence and a sense of belonging so that students feel they have a responsibility, although on the other hand there are also drawbacks. due to time constraints of students. In addition, in the inventory, the management has not deleted the recording of the inventory of facilities and infrastructure because they still prioritize the principle of benefit, as long as they can be used, the facilities and infrastructure are still used. This was done due to budget constraints

Change in seismic attenuation as a long-term precursor of gas-driven eruptions

A large fraction of volcanic eruptions do not expel magma at the Earth's surface. Although less known than magmatic eruptions, gas-driven eruptions expel fragments of preexisting rocks, volcanic gases, and steam, causing substantial casualties. The destructive potential of these eruptions lies in the difficulty in identifying clear warning signals. Some gas driven eruptions have been preceded by some physicochemical changes, but these were extremely short term (from minutes to hours), and no long term trends have been clearly evidenced so far. Here, we show that unheralded gas driven eruptions can be forecast in the long term using seismic signals recorded at nearby active craters. In particular, we have found that the most recent gas driven eruptions at Kawah Ijen (Indonesia) and Ruapehu and Tongariro (New Zealand) volcanoes were all preceded by a systematic relative increase in lower-frequency (4.5-8 Hz) seismic amplitude compared to higher frequencies (8-16 Hz) over time scales of months to years. We show that this precursory activity reflects significant increases in seismic attenuation affecting preferentially high-frequency travelling waves; this probably results from the accumulation of volatiles in the shallow crust, which increases pore pressure in small scale rock heterogeneities and eventually leads to gas-driven eruptions. Our results highlight the feasibility of better constraining the onset and the end of an unrest episode, which is of paramount importance for agencies in charge of volcano monitoring

Change in seismic attenuation as a long-term precursor of gas-driven eruptions

Abstract A large fraction of volcanic eruptions do not expel magma at the Earth’s surface. Although less known than magmatic eruptions, gas-driven eruptions expel fragments of preexisting rocks, volcanic gases, and steam, causing substantial casualties. The destructive potential of these eruptions lies in the difficulty in identifying clear warning signals. Some gas-driven eruptions have been preceded by some physicochemical changes, but these were extremely short-term (from minutes to hours), and no long-term trends have been clearly evidenced so far. Here, we show that unheralded gas-driven eruptions can be forecast in the long term using seismic signals recorded at nearby active craters. In particular, we have found that the most recent gas-driven eruptions at Kawah Ijen (Indonesia) and Ruapehu and Tongariro (New Zealand) volcanoes were all preceded by a systematic relative increase in lower-frequency (4.5–8 Hz) seismic amplitude compared to higher frequencies (8–16 Hz) over time scales of months to years. We show that this precursory activity reflects significant increases in seismic attenuation affecting preferentially high-frequency travelling waves; this probably results from the accumulation of volatiles in the shallow crust, which increases pore pressure in small-scale rock heterogeneities and eventually leads to gas-driven eruptions. Our results highlight the feasibility of better constraining the onset and the end of an unrest episode, which is of paramount importance for agencies in charge of volcano monitoring.DecretOANoAutActifinfo:eu-repo/semantics/publishe

Investigation of the diurnal cycles of interferometric coherence and backscattering coefficient on irrigated wheat in the South Mediterranean

International audienc

Investigation of the diurnal cycles of interferometric coherence and backscattering coefficient on irrigated wheat in the South Mediterranean

International audienc

Temporal decorrelation of C-band radar data over wheat in a semi-arid area using sub-daily tower-based observations

International audienc

Temporal Decorrelation At C- And L-Band Over Olive Tree Plantations:First Insights From The Marocscat Campaigns

International audienc