It is often suggested that disaster education should not be a one-way knowledge transfer from disaster experts to non-experts, but a bilateral interaction between the two sides. In this study, the authors propose a new framework for disaster education based on legitimate peripheral participation (LPP) theory, in which disaster experts and non-experts interact very closely to remove the barriers between the two sides. Specifically, the present study introduces two practical research methods for disaster education. The first is an attempt to convert a seismological observatory into a disaster science museum with collaboration between seismologists (experts) and volunteer staff (non-experts). The second is an endeavor to involve elementary school children in cutting-edge seismological research by installing a miniature seismometer at their school. As a result, volunteer staff at the museum formed a new identity in joint practice as semi- experts who mediate between experts and non-experts. Although the schoolchildren did not reach a definite stage as successfully as did the volunteer workers in the museum project, through this research, both the seismologists and the children realized what they had not shared, and this marked a starting point for further risk communication. The results are discussed from the perspective of LPP theory.

View full abstract

Long-term variations in annual lightning deaths in Japan were examined in relation to the number of thunder days, on the basis of death statistics for 1909 to 2014, and police data for 1968 to 2009. The number of lightning deaths was mostly 20 to 60 people without a remarkable trend before World War II, while it rose to over 100 just after the war, and then decreased during the latter half of the 20th century to less than 10 in recent decades. For the period before 1970, the number of annual lightning deaths was positively correlated with that of warm-season thunder days (averaged over 39 stations) with a correlation coefficient exceeding 0.5. The correlation became low and insignificant after the 1980s as lightning mortality decreased, although a high correlation of 0.6-0.8 was maintained between lightning damages and thunder days. There was also a positive correlation of 0.4-0.6 between lightning deaths and warm-season mean temperature until the 1980s, corresponding to a weak correlation between thunder days and temperature.

View full abstract

On August 3, 2014 and May 29, 2015, eruptions occurred at the Shindake summit crater of Kuchinoerabujima Volcano, which is located in the Ryukyu Islands in southwestern Japan. The Japan Meteorological Agency upgraded the Volcanic Alert Level (VAL) to 3 (restricted zone within 2 km from the summit) after the 2014 eruption and to 5 (evacuation) after the 2015 eruption. The possibility of implementing early warnings for eruptions and forecasting the area most likely to suffer damage from volcanic eruptions was examined based on monitoring data and the disaster areas of historic eruptions. A long-term process spanning 15 years and a relatively short-term process that could have been implemented immediately before the onset of the 2014 eruption were identified. The seismicity, which mostly represented extremely shallow (less than 0.5 km) volcano-tectonic earthquakes beneath the summit crater, increased from July to December 1999. After the first increase in seismicity, several repeated bursts of seismicity occurred. Repeated ground inflation events around the crater detected by continuous GNSS were associated with the increase in seismicity. Increases in the activity were also accompanied by increases in geothermal and fumarolic activity. An alert zone of 1 or 2 km (VAL 2 or 3) from Shindake crater was established immediately after three bursts of volcanic earthquakes occurred during the precursory period of the 2014 eruption. However, there were no definite indications to trigger an upgrade to the VAL before the 2014 eruption because the relatively high volcanic activity had been stable and the precursory tilt change began only a short time before the eruption. The phenomena prior to the 2015 eruption were more intense than those prior to the 2014 eruption, as demonstrated by the seismicity, which included a felt earthquake six days before the eruption; the larger ground deformation; the higher rate of discharge of SO2 gas; and the higher temperature. Among these precursors, the felt earthquake could be considered an appropriate indication to trigger an upgrade of the VAL from 3 to 5 for evacuation because felt earthquakes suddenly increase the seismic energy, whereas other parameters showed gradual progress. In historical cases, a few felt earthquakes were reported prior to the eruptions in 1931 and 1966. The felt earthquake before the 2015 eruption was induced by the accumulation of other eruption-related parameters, such as an increase in the SO2 discharge rate, the inflation of the volcano, and the appearance of volcanic glow at the summit. Decreases in the seismicity, SO2 gas discharge rate, and geothermal activity led to an initial reduction of the alert zone radius to less than 2.5 km in October 2015, and a further reduction to less than 2 km (VAL 3) was later implemented based on the deflation around the summit area in June 2016.

View full abstract

The 2014 Ontake eruption and the 2011 Great East Japan Earthquake resulted in some revision of government measures for disaster prevention. The role of residents in disaster prevention is increasing. The effectiveness fusing of tourism with disaster prevention education in the disaster prevention system is confirmed in some volcanic areas. This paper focuses on the background to the rapid evacuation during the 2015 Kuchinoerabujima volcano eruption as a case study focusing on disaster prevention action and daily disaster awareness of volcanic activity. The case of the 2015 Kuchinoerabujima eruption shows that it is important to enhance relationships not only among experts, local government, residents, and the media but also among experts and non-expert residents who have an interest in volcanic activity. In Kuchinoerabujima, based on the proven program of nature study abroad, the effectiveness of fusing tourism with disaster prevention education in the disaster prevention system is confirmed. Cooperation between tourism and disaster prevention is important for the safety of visitors and the safety and livelihoods of residents.

View full abstract

At Kuchinoerabujima Volcano located in southwest Japan, eruptions occurred on August 3, 2014, and May 29 and June 18, 2015. We evaluated the seismic and acoustic waves excited by these eruptions to characterize the eruptions. First, we estimated the eruption durations at a single station. The durations were 50 s, 6 min, and 6 min for the eruptions on August 3, 2014, and May 29 and June 18, 2015, respectively. The seismic and acoustic waveforms of the 2014 eruption have spindle shapes, while the waveforms of the 2015 eruptions have initial impulsive phases followed by weak arrivals. These three eruptions were phreatomagmatic in nature, as suggested by geological surveys. Second, we estimated the seismic and acoustic energies of the eruptions. The seismic and acoustic energies of the 2014 eruption were 1.88 GJ and 0.21 GJ, respectively. The seismic and acoustic energies of the eruption on May 29, 2015 were 0.36 GJ and 2.2 GJ, respectively; and the seismic and acoustic energies of the eruption on June 18, 2015 were 0.3 GJ and 0.06 GJ, respectively. Third, we estimated the counter single force excited by the eruptions on May 29 and June 18 by using seismic waveform matching at a broadband station. The pulse width and amount of the counter force were lined on the scaling line for a conduit pressure of 6 MPa. For the 2014 eruption, the short duration and spindle-like waveforms may reflect that the eruption was short lived and initially weak, gradually becoming violent and forming fissures, while the 2015 eruptions did not form new fissures.

View full abstract

Kuchinoerabu-jima is a volcanic island in southern Kyushu, Japan. On August 3, 2014, a moderate summit eruption occurred, destroying all the observation stations near the summit. By using an unmanned aerial vehicle (UAV), a helicopter in our case, we installed four stations in the summit area in April 2015. We also conducted multi-parameter observations including an aero-magnetic survey, visual and infrared observation, and gas measurements and sampling. A summit eruption occurred again on May 29, 2015. It was far larger than the previous one and the entire island was evacuated. The seismometers installed in April were all destroyed but they detected changes in seismic activity a few days before the eruption. In September 2015, we installed five seismometers again. We also conducted multi-parameter observations as in April. A comparison of the two observations in April and September shows a clear decline in volcanic activity. Proximal data are sensitive to the volcanic activity, but difficult to acquire. UAV observation clearly compensates for the lack of data near the summit of the volcano. Together with other information, the UAV-acquired information contributed to reducing the alert level by the local government (Yakushima Town), and thus contributed to the evacuees being able to return in December 2015.

View full abstract

The volcanic island of Kuchinoerabujima recently erupted on Aug. 3, 2014 and on May 29, 2015. After the 2014 eruption, a gradual increase of sulfur dioxide (SO2) flux from the volcano was observed. In response to the increase, we built a UV spectrometer system that can be operated semi-automatically without an experienced observer for repetitive flux monitoring. The monitoring was carried out based on a traverse method using a regular service ferry as a carrier. With the repetitive measurements, we detected a sudden flux increase to over 2500 ton/day at the end of Nov. 2014, a high and variable flux after mid-March to early-May 2015, and a continued decreased flux (<500 ton/day) before the May 29, 2015 eruption. The detected SO2 flux variations showed that a large amount of magma was involved in gas emissions at the volcano, the conduit system became unstable from mid-March, and the conduit system became partially sealed about one week before the 2015 eruption, which was probably the turning point toward the eruption. The repetitive SO2 flux monitoring using a regular public transportation made it possible to detect important changes of flux before the eruption and was very effective for understanding the process toward the 2015 eruption.

View full abstract

The remarkable eruption on Kuchierabujima, which occurred on May 29, 2015, had the potential to disrupt land seismic observation if the volcanic activities had expanded. Since relatively deep-volcano-tectonic (DVT) earthquakes under the volcano may have extended into the sea region around the island, we deployed four ocean bottom seismometers (OBSs) on the seafloor at distances at approximately 6.5 km from the crater. During the OBS observation period from July 3 to October 9, 2015, 303 volcanic earthquakes were detected. The daily numbers and the temporal amplitude changes indicate that seismic activities declined in the middle of August. However, only nine of the events were DVT earthquakes, and we were unable to identify any clear differences between the hypocenter distribution characteristics of the DVT events discussed in previous studies and those of our observations. However, since the temporal tendency of daily earthquake numbers derived from our OBS data resembled that compiled by the Japan Meteorological Agency using real-time land data, when eruption expansions occur on a small-scale remote island such as Kuchierabujima, OBS observations can provide a useful backup to efforts aimed at grasping the seismicity.

View full abstract

We conducted precise leveling surveys in Kuchierabujima Volcano, southwest Japan seven times after the occurrence of the 3 August 2014 eruption, in order to detect the vertical ground deformation associated with the eruptions that occurred in 2014 and 2015. The first survey data obtained in August 2014 suggest that vertical displacements associated with the 3 August 2014 eruption were not remarkable on the leveling route, which is located >2.3 km away from Shindake crater. On the other hand, the obvious ground uplift toward the central part of the volcanic edifice was detected during the period between August 2014 and March 2015 surveys. The results of the pressure source analysis suggest that the rapid magma input occurred at a relatively large depth (optimally 7.0 km) and led to the large eruption on May 29, 2015. The ground uplift remained unchanged until at least October 2015, even after the eruptions on 29 May and 18 June 2015. During the period between June and September 2016 surveys, a significant ground subsidence was observed, suggesting that most of the stored magma was removed during this period.

View full abstract