/pdf/ionospheric-detection-of-natural-hazards-39q4arpkq4.pdf

Ionospheric Detection of Natural Hazards

Using data from ground-based GNSS-receivers located in southern Chile, we study the ionospheric total electron content (TEC) response to two eruptions of the Calbuco volcano that occurred on 22-23 April 2015. In both cases, the TEC response showed quasi-periodic signals with several consecutive wave-trains. The averaged amplitude of the observed co-volcanic TEC-perturbations amounted 0.45 TECU for the first eruption and 0.16 TECU for the second one. We compare amplitudes of the TEC response to volcano eruptions of different intensity from our and previously published data, and we show that both the intensity and the background ionospheric conditions define the amplitude of ionospheric co-volcanic disturbances (CVID). The relative contribution, however, scales with the eruption intensity.

The travel-time diagrams allowed to estimate the propagation speed of the observed co-volcanic TEC perturbations as ~900-1200 m/s, which is close to the acoustic (or shock-acoustic) waves speed at the ionospheric height. The spectrograms are consistent with the conclusion on the acoustic nature of the observed TEC perturbations.

Finally, we use the approximation of a spherical wave propagating at a constant velocity from a point source and, for the first time, we calculate the location of the volcanic source and the onset time of the volcano eruption from ionospheric measurements. We show that even from 30-sec ionospheric GPS data it is possible to “localize” the eruptive source within several degrees of latitude/longitude.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2016JA023382

Ionospheric detection and localization of volcano eruptions on the example of the April 2015 Calbuco events

Upper Atmospheric Responses to Surface Disturbances: An Observational Perspective

A sequence of a plinian eruption preceded by dome destruction at Kelud volcano, Indonesia, on February 13, 2014, revealed from tephra fallout and pyroclastic density current deposits

The short period seismometer-based magnitude saturation problem, especially for events with magnitude > 8, can be improved by a real-time Global Navigation Satellite System (GNSS) positioning technique, which has enabled rapid estimation of a finite fault model for a large earthquake without any saturation. A new real-time fault modeling system based on the GNSS Earth Observation Network (GEONET) is developed and is under experimental operation in Japan. In this paper, we present the newly developed system REGARD (the Real-time GEONET Analysis system for Rapid Deformation monitoring), which consists of real-time GNSS positioning, automatic detection of coseismic displacement by the event, and quasi real-time finite fault model inversion routines. The performance of the automatic event detection system is tested through experimental real-time operation based on GEONET data for two months. Furthermore, we also test the reliability of the finite fault model inversion routines using real raw GNSS data observed for past large earthquakes: the 2003 Tokachi-oki earthquake (moment magnitude (Mw) 8.3), the 2011 Tohoku earthquake (Mw 9.0), and the 2011 off Ibaraki earthquake (Mw 7.7). A simulated 1707 Hoei-type Nankai Trough earthquake (Mw 8.7) is also tested. The real-time experimental operation shows that real-time GNSS positioning is precise enough to detect all the tested earthquakes, and the inversion results demonstrate that the REGARD can reliably estimate the earthquake size and its extent within 3 min after the origin time. These results suggest that the REGARD system will complement the seismometer-based magnitude determination system.

REGARD: A new GNSS-based real-time finite fault modeling system for GEONET

Atmospheric resonant oscillations by the 2014 eruption of the Kelud volcano, Indonesia, observed with the ionospheric total electron contents and seismic signals

https://www.ep.sci.hokudai.ac.jp/~heki/pdf/Nakashima_etal_EPSL2016.pdf

Kelud volcano, Indonesia, observed with the ionospheric total electron contents and seismic signals

Simulation of the 2018 Tsunami Due to the Flank Failure of Anak Krakatau Volcano and Implication for Future Observing Systems

Surabaya is the second largest city in Indonesia and the capital of East Java Province with rapid population and industrialization. The impact of urbanization in the big city can suffer potential disasters either nature or anthropogenic such as land subsidence and flood. The pattern of land subsidence need to be mapped for the purposes of planning and structuring the city as well as taking appropriate policy in anticipating and mitigating the impact. This research has used interferometric Synthetic Aperture Radar (InSAR) Small Baseline Subset (SBAS) technique and applied time series analysis to investigate land subsidence occured. The technique includes the process of focusing the SAR data, incorporating the precise orbit, generating interferogram and phase unwrapping using SNAPHU algorithms. The results showed land subsidence has been detected during 2014-2017 over Surabaya city area using ALOS-2/PALSAR-2 images data. These results reveal the subsidence has observed in several area in Surabaya in particular northern part reach up to ~2 cm/year. The fastest subsidence occurs in highly populated areas suffer vulnerable to flooding and sea level rise impact. In urban areas we found a correlation between land subsidence with residential or industrial land use. It concludes that land subsidence is mainly caused by ground water consumption for industrial and residential use respectively.

https://iopscience.iop.org/article/10.1088/1755-1315/98/1/012010/pdf

Arif Aditiya

Papers

Atmospheric resonant oscillations by the 2014 eruption of the Kelud volcano, Indonesia, observed with the ionospheric total electron contents and seismic signals

Kelud volcano, Indonesia, observed with the ionospheric total electron contents and seismic signals

Simulation of the 2018 Tsunami Due to the Flank Failure of Anak Krakatau Volcano and Implication for Future Observing Systems

Land Subsidence Monitoring by InSAR Time Series Technique Derived From ALOS-2 PALSAR-2 over Surabaya City, Indonesia

Ionospheric disturbances by volcanic eruptions by GNSS-TEC: Comparison between Vulcanian and Plinian eruptions