Precursory tilt changes associated with a phreatic eruption of the Hakone volcano and the corresponding source model

Abstract The 2015 unrest of the Hakone volcano in Japan, which began on April 26, generated earthquake swarms accompanied by long-term deformation. The earthquake swarm activity reached its maximum in mid-May and gradually calmed down; however, it increased again on the morning of June 29, 2015. Simultaneously with the earthquake increase, rapid tilt changes started 10 s before 07:33 (JST) and they lasted for approximately 2 min. The rapid tilt changes likely reflected opening of a shallow crack that was formed near the eruption center prior to the phreatic eruption on that day. In this study, we modeled the pressure source beneath the eruption center based on static tilt changes determined using both tilt meters and broadband seismometers. In the best-fit model, the source depth was 854 m above sea level, and its orientation (N316°E) agreed with the direction of maximum compression estimated based on focal mechanism and S-wave splitting data. The extent of the crack opening was estimated to be 4.6 cm, while the volume change was approximately 1.6 × 105 m3. The top of the crack reached to approximately 150 m below the eruption center. Because the crack was too thin to be penetrated by magma, the crack opening was attributed to the intrusion of hydrothermal water. This intrusion of hydrothermal water may have triggered the phreatic eruption. Reverse polarity motion with respect to that expected from crack opening was recognized in 1 Hz tilt records during the first 20 s of the intrusion of hydrothermal water. This motion, not the subsidence of volcanic edifice, was responsible for the observed displacement

MOESM1 of Precursory tilt changes associated with a phreatic eruption of the Hakone volcano and the corresponding source model

Additional file 1. Comparison of synthetic apparent tilt motions calculated using four time functions. Examples of the time functions of source expansion are shown in the left panel. F1 [Eq. (2)] was used in this study with the time constant T set to 45 s. F2 is an exponential relaxation function represented by 1 − exp(−t/T) with T set as 45 s. F3 and F4 are smoothed ramp functions (0.5 × (1.0 + tanh((4.0 × t)/Tr))) with the rise time Tr set to 60 and 120 s, respectively. The right panel shows the apparent tilt motions calculated using the functions in the left panel. The NS component of tilt change observed at KZR is indicated by the orange line

MOESM2 of Precursory tilt changes associated with a phreatic eruption of the Hakone volcano and the corresponding source model

Additional file 2. The map represents surface slope gradation. The location of the best-fit model (red rectangle), the eruption center (red circle), and tilt observation stations (white triangles) are shown in the map. Yellow arrows indicate the locations of old fissures

Genome-Wide Analysis of DNA Methylation and Expression of MicroRNAs in Breast Cancer Cells

DNA methylation of promoters is linked to transcriptional silencing of protein-coding genes, and its alteration plays important roles in cancer formation. For example, hypermethylation of tumor suppressor genes has been seen in some cancers. Alteration of methylation in the promoters of microRNAs (miRNAs) has also been linked to transcriptional changes in cancers; however, no systematic studies of methylation and transcription of miRNAs have been reported. In the present study, to clarify the relation between DNA methylation and transcription of miRNAs, next-generation sequencing and microarrays were used to analyze the methylation and expression of miRNAs, protein-coding genes, other non-coding RNAs (ncRNAs), and pseudogenes in the human breast cancer cell lines MCF7 and the adriamycin (ADR) resistant cell line MCF7/ADR. DNA methylation in the proximal promoter of miRNAs is tightly linked to transcriptional silencing, as it is with protein-coding genes. In protein-coding genes, highly expressed genes have CpG-rich proximal promoters whereas weakly expressed genes do not. This is only rarely observed in other gene categories, including miRNAs. The present study highlights the epigenetic similarities and differences between miRNA and protein-coding genes

MOESM2 of Analyzing the continuous volcanic tremors detected during the 2015 phreatic eruption of the Hakone volcano

Additional file 2. Temporal changes in amplitude ratios during volcanic tremor. This file shows the temporal changes in the amplitude ratios among the stations near the vents