JP2005024366A - Volcanic lava flow prediction system - Google Patents

Abstract

A system for predicting and calculating in real time an area where a flowing lava flow reaches during a volcanic eruption is provided.
SOLUTION: Prediction calculation of the area where the lava flow reaches by analyzing the thermal flow of the lava flow using the elevation distribution on the terrain as the initial value and the flow rate and temperature of the erupting lava flow changing with the crater position and time as boundary conditions Analyzing means 21 is provided. In addition, the distance and thickness, total volume, flow rate, and temperature of the lava flow are measured by measuring the altitude distribution and temperature distribution of the lava flow from the air and using a ranging device and thermometer from the air. Measuring means 14 for calculating The flow of the lava flow calculated based on this measurement value and the measured temperature are communicated to the analysis means 21 to predict and calculate the area where the lava flow reaches.
[Selection] Figure 1

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a volcanic lava flow prediction system that predicts in real time a damaged area caused by a lava flow during a volcanic eruption.
[0002]
[Prior art]
Non-Patent Documents 1 and 2 disclose systems for analyzing volcanic lava flows. Non-Patent Document 1 is a two-dimensional model that predicts the lava flow arrival area using the topographic data as the initial value and the flow rate and temperature of the erupting lava flow from the crater as boundary conditions in order to predict the damage caused by the lava flow in a volcanic disaster. This is an analysis method.
[0003]
Non-Patent Document 2 by the present inventors is a three-dimensional analysis method for predicting a lava flow arrival region using topographic data as an initial value and the flow rate and temperature of a lava flow ejected from a crater as boundary conditions.
[0004]
Moreover, the earthquake prediction alerting | reporting system by patent document 1 is proposed. This is to determine the necessity of notification from measurement data at the time of the occurrence of an earthquake detected by a pre-installed earthquake observation network, and to calculate the earthquake arrival time and earthquake intensity by calculating the propagation of the seismic wave It is.
[0005]
[Non-Patent Document 1]
Volcano Vol. 2 (Volume 33, Izu Oshima Eruption Special Issue S64-S76, 1988)
[Non-Patent Document 2]
Proceedings of the Annual Meeting of the Volcano Society of Japan 2002 (No. 2, 189 pages)
[Patent Document 1]
Japanese Patent Laying-Open No. 2003-66152 (paragraphs 0008-0014, FIG. 1)
[0006]
[Problems to be solved by the invention]
In the conventional techniques described in Non-Patent Documents 1 and 2, although lava flow prediction calculation can be performed, the measurement value is not used as a boundary condition, so analysis accuracy is not sufficient for real-time prediction. In addition, since the measured value is not used as the initial value, once there was a discrepancy between the calculated value and the measured value, it was necessary to correct the analysis parameters from the beginning of lava flow ejection and recalculate.
[0007]
In the prior art described in Patent Document 1, it is necessary to construct an earthquake observation network in advance in order to obtain data for calculating prediction information. Also, unlike the propagation of seismic waves, lava flows show complex heat flow behavior due to forces such as inertia, viscosity, pressure, and gravity on undulating terrain, making it difficult to apply this method.
[0008]
An object of the present invention is to provide a volcanic lava flow prediction system that predicts in real time an area where a lava flow will reach based on lava flow measurement data. According to the system of the present invention, the prediction accuracy of the lava flow arrival area can be improved and the reliability can be improved.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is a volcanic lava flow prediction system for predicting the arrival area of a lava flow at the time of volcanic eruption, from the air or on the ground, the arrival area of the lava flow, the elevation distribution of the lava flow and the lava flow temperature. The lava flow thickness distribution is calculated from the difference between the lava flow upper surface elevation distribution and the topographical elevation distribution, and the lava flow volumetric flow rate based on the lava flow thickness distribution and the arrival area of the lava flow Analyzing the thermal flow of the lava flow using the above-mentioned altitude distribution on the terrain as the initial value, and using the crater position, time-varying volume flow or mass flow of the lava flow and lava flow temperature or its specific enthalpy as boundary conditions And an analysis means for predicting the arrival area of the lava flow.
[0010]
Thereby, since the area where the lava flow reaches can be predicted in real time based on the measurement data of the lava flow, a highly reliable volcanic lava flow prediction system can be provided.
[0011]
Further, the analysis means gives the lava flow thickness distribution and the lava flow temperature as initial values to the area where the lava flow has already reached after the start of lava flow ejection.
[0012]
Alternatively, each time the measuring means measures the lava flow arrival area, lava flow upper surface elevation distribution and lava flow temperature, the analyzing means calculates the lava flow thickness distribution and lava flow temperature for the area where the lava flow has already reached. As an initial value, and re-calculate the heat flow analysis as a boundary condition of the volume flow rate or mass flow rate of the erupting lava flow and the lava flow temperature or specific enthalpy changing with time, and the lava flow arrives The predicted area is updated sequentially as the calculation progresses.
[0013]
Thereby, waste of time due to calculation from the start of lava flow ejection can be eliminated, and occurrence of prediction errors from the start of lava flow ejection to the lava flow measurement time can be avoided.
[0014]
In addition, the flow velocity distribution at the lava flow boundary is measured, and the volumetric flow rate of the lava flow ejected from the crater is calculated by the product of the boundary area and the flow velocity.
[0015]
Alternatively, the difference in the total volume of the lava flow between the two measurement times calculated based on the arrival area of the lava flow and the elevation distribution of the lava flow according to the measurement time at least twice by the measurement means is the time difference between the two measurement times. To obtain the volume flow rate. As a result, the accuracy of the volume flow rate is improved.
[0016]
In addition, the laminar flow volume flow predicted by the analysis unit is less than the lava flow volume flow rate calculated by the calculation unit based on the measured value after a lapse of a predetermined time after the start of the calculation by the analysis unit. In this case, the laminar flow volumetric flow rate is increased relative to the value at the start of the calculation, and if the predicted lava flow volumetric flow rate is excessive, the lava flow volumetric flow rate is increased relative to the value at the start of the calculation. Decrease and recalculate the area where the lava flow will reach.
[0017]
Alternatively, after starting the calculation by the analysis means, the lava flow volume flow predicted by the analysis means is equal to or less than the lava flow volume flow calculated by the calculation means and the lava flow thickness distribution predicted by the analysis means Is larger than the lava flow thickness distribution measured by the measurement means, the viscosity coefficient of the lava flow is decreased with respect to the value at the start of the calculation, and the volume flow rate of the lava flow predicted by the analysis means Is more than the volume flow rate of the lava flow calculated by the calculating means, and the lava flow thickness distribution predicted by the analyzing means is smaller than the lava flow thickness distribution measured by the measuring means, Increase the viscosity coefficient of the flow with respect to the value at the start of the calculation, and recalculate the area where the lava flow reaches.
[0018]
Alternatively, after starting the calculation by the analysis means, the lava flow volume flow predicted by the analysis means is equal to or less than the lava flow volume flow calculated by the calculation means and the lava flow thickness distribution predicted by the analysis means Is larger than the lava flow thickness distribution measured by the measuring means, the lava flow temperature is increased with respect to the value at the start of the calculation, and the volume flow rate of the lava flow predicted by the analyzing means is increased. When the lava flow thickness distribution calculated by the calculating means is equal to or greater than the laminar flow thickness distribution calculated by the analyzing means and is smaller than the lava flow thickness distribution measured by the measuring means, Recalculate the area where the lava flow reaches by reducing the temperature of
[0019]
Thereby, since the prediction precision of the lava flow arrival area improves, a highly reliable volcanic lava flow prediction system can be provided.
[0020]
The measuring means has a distance measuring device for measuring the arrival area of the lava flow using electromagnetic waves or optics from an aircraft, a communication satellite, or the ground, and the absolute coordinates composed of the latitude, longitude, and altitude of these distance measuring devices are obtained. It is determined by the radio wave of the position measurement system (GPS) by satellite, and the latitude and longitude of the boundary of the arrival area of the lava flow are measured.
[0021]
Thereby, the measurement accuracy of the lava flow rate is improved, and the prediction accuracy of the arrival area by the analysis means can be improved.
[0022]
It also generates initial values including the elevation distribution on the topography, the reach of the measured lava flow, the reached lava flow thickness distribution, and the temperature distribution, the crater position, the volumetric flow rate or mass flow rate of the lava flow that changes over time, temperature Alternatively, an input data generation calculation module that generates a boundary value including specific enthalpy, an analysis calculation module that predicts an arrival area of the lava flow by inputting the initial value and the boundary condition, and an estimated calculation area of the arrival of the lava flow A computer having display means for displaying;
[0023]
The display means compares and displays the current arrival area of the lava flow and the expected arrival area of the lava flow after a predetermined time.
[0024]
Thereby, the measurement accuracy of the lava flow rate improves. In addition, it is possible to prevent a change in the computer occupancy ratio between measurement, prediction calculation, and result display functions due to an increase in calculation load, and a stagnation of the entire system due to a computer failure related to one function.
[0025]
Moreover, since the predicted value of the lava flow arrival area at a plurality of times can be displayed when recalculation is performed by inputting the measured value or during the prediction calculation, the visibility of the calculation result can be improved.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a volcanic lava flow prediction system according to an embodiment, FIG. 2 is a conceptual diagram of an analysis sequence, and FIG. 3-5 is an explanatory diagram of a lava flow arrival area prediction result.
[0027]
In FIG. 1, a crater 2 is generated at the summit or hillside of a volcano 1, and a lava flow 3 is ejected together with fumes 12. The lava flow 3 flows down due to the slope of the mountainside, and a residential area 7 exists in the flow direction. Hereinafter, the volcanic lava flow prediction system will be described by dividing it into a lava flow measuring means 14 and an analysis means 21 for predicting and calculating the arrival area of the lava flow 3.
[0028]
In this embodiment, the lava flow measuring means 14 is mainly a helicopter 5 which is a kind of wingless aircraft, or a distance measuring device mounted on the earth observation satellite 6. However, in the following, they are simply referred to as helicopter 5 or earth observation satellite 6. As a measurement system, a winged aircraft can also be used. Moreover, you may measure by installing a measuring device on the ground surface.
[0029]
In order to determine the coordinates of the measurement target, the position of the helicopter 5 itself, which is the measurement base, is measured by radio waves from the GPS satellites 27, 28, which are position measurement systems. In addition, in order to improve the accuracy of position measurement, it is also effective to set a ground station at the lava flow unreachable point around the lava flow and determine the base point of the ground surface. A distance measuring electromagnetic wave 8 is radiated to the lava flow 3 from the distance measuring device of the helicopter 5. For distance measurement, a light wave such as a laser, or a sound wave can be used. Alternatively, the ranging electromagnetic wave 9 is radiated to the lava flow 3 from the ranging device of the earth observation satellite 6. The earth observation satellite 6 can also use a light wave such as a laser for distance measurement.
[0030]
The calculation means included in the distance measuring device obtains the elevation of the upper surface of the lava flow 3 for each latitude and longitude coordinate measured by the distance measuring electromagnetic wave 8. The thickness distribution of the lava flow 3 with respect to the latitude and longitude coordinates is obtained by subtracting the elevation before the volcanic eruption for each measured latitude and longitude coordinates from the elevation of the lava flow. Further, the volume of the lava flow 3 is obtained by multiplying the thickness of the lava flow 3 for each latitude and longitude coordinate by the horizontal plane area of the measurement mesh element for each latitude and longitude coordinate and integrating the thickness over the entire surface of the lava flow. .
[0031]
The calculation means of the distance measuring device divides the measured volume of the lava flow 3 by the elapsed time from the start of ejection of the lava flow 3 to the time of measurement to obtain the volume increase per unit time, that is, the volume flow rate. On the other hand, on the helicopter 5, the temperature of the lava flow 3 is measured using an infrared thermometer, which is one of the measuring means 14.
[0032]
In addition, the thickness of lava flow 3 for each latitude and longitude coordinate is arranged on the topographic map, and thickness 0 is measured as “unreachable”, and when the thickness is a significant value, it is determined as “reached”. Sometimes the area where the lava flow 3 has reached can be given as numerical data. The position of the crater 2 can be obtained by visually checking the spray of the lava flow 3 and digitizing the position coordinates on the latitudinal and longitude of the thickness distribution measurement of the lava flow 3 on the topographic map. In addition, as the position measurement method of the crater 2, the thickness is large in the lava flow 3 by the method using the coordinate that recorded the maximum temperature by the temperature measurement or the dynamic pressure of the flow of the lava flow 3 rising from the ground Can be determined using the coordinates.
[0033]
The above measurement data from the distance measuring device and the thermometer is transmitted from the helicopter 5 and the earth observation satellite 6 to the radio wave reception relay facility 4 and sent to the analysis means 21. As for the calculation means, the distance measuring device, the relay facility 4 or the analysis means 21 may be provided with all of the functions or may be arranged in a shared manner.
[0034]
Next, analysis means will be described. In FIG. 1, the analysis means 21 includes an input data generation computer module 22, an analysis computer module 23, a data output computer module 24, a result display / command input console 25, a file system 26, and the like. Measurement data such as the thickness distribution, volume, flow rate, temperature, arrival area, and coordinates of the crater 2 of the lava flow 3 is transmitted from the measurement system 14 via the radio wave reception relay facility 4.
[0035]
The measurement data is input to the input data generation computer module 22, and the analysis coordinates based on the topography before the eruption of the volcano 1 are correlated with the position of the crater 2, the thickness distribution of the lava flow 3, and the temperature distribution. Moreover, the volume flow rate data of the lava flow is multiplied by the mass of the lava flow to convert it into a mass flow rate, and conversion from temperature to specific enthalpy is also performed here. In addition, the ambient temperature is set, and if there are lakes, seas, etc. around Volcano 1, the water level distribution and water temperature are set. Also, the composition of the lava flow 3 can be input.
[0036]
In addition to the above, the input data generation computer module 22 may calculate the lava flow thickness distribution for the latitude and longitude coordinates by subtracting the elevation before the volcanic eruption from the lava flow top elevation measured by the distance measuring means. Good. Alternatively, the lava flow thickness for each latitude and longitude may be multiplied by the horizontal plane area of the measurement mesh element for each latitude and longitude and integrated over the entire surface of the lava flow to obtain the lava flow volume. Further, the volume flow rate may be obtained by dividing the lava flow volume by the elapsed time from the start of lava flow ejection to the time of measurement.
[0037]
Among the measurement data, the lava flow thickness distribution and temperature distribution in the area where the lava flow 3 that has already flowed down are the initial values of the analysis computer module 23 described below, and the mass flow rate, specific enthalpy, and atmosphere of the lava flow 3 are as follows. Temperature, water level, water temperature, etc. are boundary conditions.
[0038]
The mass initial value and mass flow rate obtained from the lava flow thickness are used in the mass conservation equation of the thermal fluid analysis model, and the specific enthalpy per unit mass is used in the energy conservation equation of the thermal fluid analysis model. Thus, the transport of mass and energy is solved. Atmosphere temperature, water level, and water temperature are used to calculate the amount of heat transfer between the lava flow and the atmosphere, and increase or decrease the energy due to heat transfer in the energy conservation equation. Here, mass and volume are correlated by density, and specific enthalpy and temperature are correlated through specific heat and latent heat. Therefore, not only mass and specific enthalpy but also volume and temperature can be used in the analysis.
[0039]
In the figure, A1 is measurement data, A2 is an initial value, boundary condition data, A3 is a predicted calculation value, A4 is a measurement value of a lava flow arrival area, and A5 is a prediction calculation value of a lava flow arrival area. On the other hand, C1 is an input data generation computer module control command, C2 is an analysis computer module control command, and C3 is a data output computer module control command.
[0040]
The analysis computer module 23 starts an analysis each time the initial value and boundary condition data are generated by the input data generation computer module 22. At this time, if a plurality of computer processors are used, the calculation being performed can be continued regardless of the data input from the input data generation computer module 22.
[0041]
The analysis computer module 23 theoretically analyzes the heat flow of the lava flow 3 by using the analysis model exemplified in “Proceedings of the Annual Meeting of the Volcano Society of Japan 2002, No. 2, page 189”.
[0042]
The analysis model exemplified here treats a lava flow as a Newtonian fluid and solves a three-dimensional mass, momentum, and energy equation. The change of boundary conditions due to lava flow spreading and solidification / stopping due to cooling is updated for each calculation step, making it possible to analyze the behavior of a solid fluid like a lava flow. In the analysis model, this prediction system is extended to volcanic mud flow and volcanic debris flow by modifying the physical property value function for volcanic mud flow and volcanic debris flow other than lava flow and incorporating changes in stop boundary conditions into the analytical model. It is also possible to do.
[0043]
Here, in order to predict the arrival area of the lava flow 3, the calculation time needs to be shorter than the actual phenomenon time. Hereinafter, a method for predicting and calculating the arrival area of the lava flow 3 in the case where the calculation time is 1/6 of the actual phenomenon time in FIG. 2 will be described.
[0044]
In FIG. 2, the horizontal axis represents the elapsed time after the lava flow 3 is ejected, and the vertical axis represents the number of analysis cases updated each time measurement data is input. The solid line arrow in the figure is the calculation time, and the horizontal broken line arrow is the actual phenomenon time predicted by the calculation. Therefore, when the real time is at the position of the tip of the solid arrow, the arrival area of the lava flow 3 at the tip of the broken arrow can be predicted.
[0045]
The eruption of lava flow 3 begins at time 0h, and the analysis system 21 starts calculating the analysis sequence (1). In this initial stage, measurement data is not obtained, so a provisional value obtained by visual inspection or the like is input for calculation. In this example, by the time measurement data from the first measurement system 14 is transmitted at time 1h (A in FIG. 2), a predicted calculation value of the arrival area of the lava flow 3 after 6h is obtained. By comparing the predicted calculation value obtained at time 10 min (actual time 1 h of the predicted event) with the actual measured value of the arrival area of lava flow 3 in the measurement data 14 from the first (time 1 h) measurement system 14, the analysis sequence Analysis parameters in (1) can be evaluated.
[0046]
Using the measurement data from the first measurement system 14, the calculation of the analysis series {circle around (2)} is started from time 1h. By calculating for one hour, a predicted calculated value at time 7h at time 2h, a predicted value at time 13h at time 3h, and a predicted calculated value at time 19h at time 4h are obtained.
[0047]
Fig. 3 shows the topographic map (Geographical Survey Institute) of the output result of the predicted area of arrival of lava flow 3 obtained at time 4h and the measured value 32 of the arrival area of lava flow at time 4h in analysis series (2). It is superimposed on the basic volcano map 31). In the figure, the measured value 32 of the lava flow arrival area at time 4h is shown in black, and the predicted calculated values 33, 34, and 35 in 7h, 13h, and 19h thereafter are shown as solid lines.
[0048]
Since such a superposition diagram is displayed through the data output computer module 24 in conjunction with the progress of the calculation and is displayed on the result display / command input console 25 which is a display device showing the actual time of the predicted event, the calculation result Visibility can be improved.
[0049]
According to the same measurement, the analysis sequence is advanced, and the third measurement value of FIG. 2 is obtained at time 7h as shown in FIG. 4 and is superimposed on the predicted calculation value of the analysis sequence (2). In FIG. 4, since the predicted calculation value 33 at the time 7h of the analysis sequence (2) is compared with the third measurement value, the analysis parameter can be evaluated. The result is reflected in the calculation of the analysis series (4). FIG. 5 shows an update of the predicted calculation value 34 of the analysis sequence {circle around (2)} in FIG. 4 using the predicted calculation value 37 of the analysis sequence {circle around (3)} calculated based on the measurement value at time 4h. is there.
[0050]
According to the volcanic lava flow prediction system of the present embodiment, the lava flow arrival area can be accurately predicted by using the measured value as the initial value of the next analysis series, which has the effect of improving the reliability. .
[0051]
Next, a second embodiment of the present invention will be described. FIG. 6 is a conceptual diagram of the measured values of the arrival area of the lava flow, and FIG. 7 is a conceptual diagram of the flow velocity distribution of the lava flow. The lava flow calculation method of the volcanic lava flow real-time prediction system is explained.
[0052]
In the first embodiment, when the flow rate of the lava flow is obtained, the volume of the measured lava flow is divided by the elapsed time from the start of the lava flow ejection to the measurement time, and the volume increase per unit time, that is, Volume flow was obtained. This is a method of giving an average flow rate, and it is difficult to reflect the fluctuation of the lava flow in the analysis. The second embodiment is a method for accurately calculating the lava flow rate from the lava flow arrival area measurement values in the same volcanic lava flow real-time prediction system as in the first embodiment.
[0053]
FIG. 6 shows a lava flow 41 ejected from the crater 40 during the Nth measurement and a lava flow 42 during the (N + n) th measurement. The volume of the lava flow 41 is measured at the N-th measurement, and the volume of the lava flow 42 is measured at the (N + n) -th measurement. Here, N and n are arbitrary integers. The volume of the lava flow 41 is subtracted from the volume of the lava flow 42 at this time, and the volume increment between the Nth time and the (N + n) th time is obtained. Further, the time interval between the two measurements is calculated by subtracting the Nth measurement time from the (N + n) th measurement time. By dividing the volume increment by the time interval between the two measurements, the volume increase rate between the two measurements, that is, the volume flow rate between the target times can be accurately obtained.
[0054]
According to this method, since the accuracy of lava flow measurement can be improved, the prediction accuracy of the lava flow arrival area can be further improved.
[0055]
In the case of the measurement method of FIG. 6, at least two or more measurements are required to obtain the volume difference of the lava flow at a plurality of time intervals. Moreover, in order to improve measurement accuracy when the lava flow is small, it is necessary to lengthen the measurement interval.
[0056]
FIG. 7 is a conceptual diagram illustrating another lava flow calculation method. In the method of FIG. 7, the surface of the lava flow 44 is cut into a lava flow surface velocity measurement matrix 43 with a constant interval, and the moving speed of the lava flow surface in each matrix 43 is measured. For the measurement, a laser measuring instrument or an image processing technique is used. The vector of the moving velocity is obtained, and each mesh element surface area of the lava flow surface velocity measuring matrix 43 is multiplied for each vector normal component, and the product is accumulated over the entire matrix. This integrated value is the volume flow rate of the lava flow 44.
[0057]
According to this method, since the lava flow rate can be measured by one measurement, there is an advantage that the lava flow rate can be measured in a short time.
[0058]
In addition to the effects of the first embodiment, the volcanic lava flow real-time transition prediction system according to the second embodiment can accurately measure the flow rate of the lava flow in a short time. As a result, it is possible to further shorten the predicted time for the arrival area of the lava flow, and it is easy to evacuate from the damaged area, thereby improving safety.
[0059]
Next, a real-time volcanic lava flow prediction system according to a third embodiment of the present invention will be described. FIG. 8 is a configuration diagram of the analysis computer module. FIG. 9 is a conceptual diagram showing a lava flow shape.
[0060]
The analysis computer module 23 includes an initial value setting unit 51, a boundary condition setting unit 52, a heat flow calculation unit 53, a physical property value calculation unit 54, a measured calculation value / analysis predicted value comparison unit 55, an initial value correction unit 56, and a boundary condition correction. The unit 57 is configured.
[0061]
The initial value calculated by the input data generation computer module 22 of FIG. 1 based on the measurement enters the calculation code initial value setting unit 51. Here, initial values are set using physical property values such as density, viscosity, thermal conductivity, and specific heat calculated by the physical property value calculation unit 54. Next, the boundary condition calculated by the input data generation computer module 22 of FIG. 1 based on the measurement enters the boundary condition setting unit 52 and becomes the boundary condition in the repeated calculation of the heat flow calculation unit 53. In the boundary condition setting unit 52 and the heat flow calculation unit 53, the values calculated by the physical property value calculation unit 54 are used as the physical property values such as density, viscosity, thermal conductivity, and specific heat. The calculation result output 60 of the heat flow calculation unit 53 is sent to the data output computer module 24 of FIG.
[0062]
The analytical computer module 23 described above is provided with a measured calculation value / predicted calculation value comparison unit 55 that compares the calculation result output 60 and the measurement result 61. The measured calculated value / predicted calculated value comparison unit 55 compares the measured calculated value and the predicted calculated value with respect to the spread area and thickness of the lava flow, as shown in FIG. In general, the lower the lava flow temperature, the higher the viscosity of the lava flow, the lava flow spreading is suppressed, and the lava flow thickness increases.
[0063]
The measured calculated value / predicted calculated value comparison unit 55 compares the lava flow thickness distribution (expanded area and thickness) based on the measured calculated value with the predicted calculated lava flow thickness distribution (expanded area and thickness). When it is determined that the lava flow spread prediction calculation result 71 is thinner and wider than the lava flow spread measurement calculation result 72, the measured calculation value / predicted calculation value comparison unit 55 sends an initial value correction unit 56 and a boundary condition correction unit 57. A lava flow temperature correction signal 63 is issued to lower the lava flow temperature of the initial value and the boundary condition. Instead of the temperature correction, the physical property value correction signal 62 for increasing the viscosity of the lava flow may be output from the measured calculation value / predicted calculation value comparison unit 55 to the physical property value calculation unit 54.
[0064]
On the other hand, when it is determined that the lava flow spread calculation calculation result 71 has expanded to a narrower area than the lava flow spread measurement calculation result 72, the measured value / predicted calculation value comparison unit 55 and the initial value correction unit 56 and the boundary condition correction are performed. A lava flow temperature correction signal 63 is output to the unit 57 to increase the lava flow temperature of the initial value and boundary conditions. Further, the physical property value correction signal 62 for reducing the viscosity of the lava flow may be output from the measured calculation value / predicted calculation value comparison unit 55 to the physical property value calculation unit 54.
[0065]
According to this method, when predicting the arrival area of the lava flow, it is possible to accurately predict the spreading behavior of the lava flow by correcting the lava flow temperature or physical property value based on the measured calculation value. There is an advantage that the prediction accuracy of the destination area can be further improved.
[0066]
In the volcanic lava flow real-time prediction system of the third embodiment, the arrival area of the lava flow can be predicted with higher accuracy in addition to the effects of the first embodiment.
[0067]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, there exists an effect which can predict the arrival area of a lava flow accurately in a short time at the time of volcanic eruption.
[0068]
In addition, the arrival area of the lava flow can be calculated systematically using the measured values, so that the prediction calculation is highly stable and the damage prediction accuracy can be improved.
[0069]
In addition, the flow and temperature of the lava flow can be accurately calculated from the measured values, and the influence of the lava flow temperature and physical properties can be reflected in the prediction calculation, thereby improving the damage prediction accuracy.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a real-time volcanic lava flow prediction system according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram of an analysis sequence according to the first embodiment.
FIG. 3 is an explanatory diagram showing a predicted calculation result of a lava flow arrival area at time 4h.
FIG. 4 is an explanatory diagram showing a prediction calculation result of a lava flow arrival area at time 7h.
FIG. 5 is an explanatory diagram showing a prediction calculation result of a corrected lava flow arrival area at time 13h.
FIG. 6 is a conceptual diagram for explaining a lava flow rate measurement principle according to a second embodiment of the present invention.
FIG. 7 is a conceptual diagram illustrating another lava flow measurement principle according to the second embodiment.
FIG. 8 is a configuration diagram of an analysis computer module of a volcanic lava flow real-time prediction system according to a third embodiment of the present invention.
FIG. 9 is an explanatory diagram showing a comparison between a lava flow spread calculation value and a measurement value according to the third embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Volcano, 2 ... Tinder, 3 ... Lava flow, 4 ... Radio wave reception relay equipment, 5 ... Helicopter, 6 ... Earth observation satellite, 7 ... Residential area, 8 ... Electromagnetic wave for ranging, 9 ... Electromagnetic wave for ranging, 10 ... lava flow observation data, 11 ... lava flow observation data, 12 ... volcanic smoke, 14 ... measurement means, 21 ... analysis means, 22 ... input data generation computer module, 23 ... analysis computer module, 24 ... data output computer module, 25 ... Result display / command input console, 26 ... file system, 27, 28 ... GPS satellite, 30 ... crater, 31 ... topographic map, 32 ... measured value of lava flow arrival area 4 hours after lava flow ejection, 33 ... lava flow ejection Predicted calculation value of the lava flow arrival area after 7 hours, 34 ... Predicted calculation value of the lava flow arrival area after 13 hours of lava flow ejection, 35 ... Predicted calculation value of the lava flow arrival area after 19 hours of lava flow ejection, 36 Measured value of the arrival area of the lava flow 7 hours after the lava flow ejection, 37 ... Predicted calculation value of the arrival area of the lava flow 13 hours after the lava flow ejection, 43 ... Matrix of the lava flow surface velocity measurement, 44 ... Lava flow, 51 ... Initial Value setting unit 52 ... Boundary condition setting unit 53 ... Heat flow calculation unit 54 ... Physical property value calculation unit 55 ... Measured calculation value / predicted calculation value comparison unit 56 ... Initial value correction unit 57 ... Boundary condition correction unit 58 ... initial value, 59 ... boundary condition, 60 ... calculation result output, 61 ... measurement data, 62 ... physical property value correction signal, 63 ... lava flow temperature correction signal, 71 ... lava flow spread prediction calculation result, 72 ... lava flow Spread measurement calculation result, 73 ... Tinder.

Claims (11)

In the volcanic lava flow prediction system that predicts the arrival area of the lava flow during volcanic eruptions,
Measuring means to measure the lava flow arrival area, lava flow upper surface elevation distribution and lava flow temperature from the air or above the ground,
A calculation means for calculating a lava flow thickness distribution from a difference between the lava flow upper surface elevation distribution and topographical elevation distribution, and calculating a laminar flow volumetric flow rate based on the lava flow thickness distribution and the arrival area of the lava flow; ,
Analyzing the thermal flow of the lava flow using the terrain altitude distribution as an initial value, the crater position, the volumetric flow rate or mass flow rate of the lava flow and the lava flow temperature or its specific enthalpy as boundary conditions, and the area where the lava flow reaches A volcanic lava flow prediction system, comprising: In claim 1,
The said analysis means gives the lava flow thickness distribution and the lava flow temperature as an initial value with respect to the area where the lava flow has already reached after the start of lava flow ejection, The volcanic lava flow prediction system characterized by the above-mentioned. In claim 1 or 2,
Each time the measurement means measures the lava flow arrival area, lava flow top surface elevation distribution and lava flow temperature, the analysis means initially sets the lava flow thickness distribution and lava flow temperature to the area where the lava flow has already reached. The predicted area where the lava flow will arrive by sequentially recalculating the analysis of the thermal flow given as values and the volume flow or mass flow rate of the erupting lava flow and the lava flow temperature or specific enthalpy as boundary conditions A volcanic lava flow prediction system, which is updated sequentially according to the progress of calculation. In claim 1, 2 or 3,
The said calculation means is the volcanic lava flow prediction system characterized by calculating the said volume flow volume by multiplying the measured value of the three-dimensional flow velocity distribution of a lava flow boundary, and the area of a lava flow boundary element. In claim 1, 2 or 3,
The calculation means measures the difference between the lava flow total volume at the two measurement times calculated based on the lava flow arrival area and the lava flow upper surface elevation distribution according to the measurement time at least twice by the measurement means. A volcanic lava flow prediction system characterized by obtaining the volume flow rate divided by a time difference. In claim 1, 2 or 3,
After the calculation by the analyzing means is started, the calculation of the volumetric flow rate of the lava flow is started when the volumetric flow rate of the lava flow predicted by the analyzing means is too small compared to the volumetric flow rate of the lava flow calculated by the calculating means. If the estimated lava flow volumetric flow is excessive, decrease the lava flow volumetric flow relative to the value at the start of the calculation and re-establish the area where the lava flow reaches. A volcanic lava flow prediction system characterized by calculation and prediction. In claim 1, 2 or 3,
After the start of calculation by the analysis means, the volume flow of the lava flow predicted by the analysis means is equal to or less than the volume flow of the lava flow calculated by the calculation means, and the lava flow thickness distribution predicted by the analysis means is When the lava flow thickness distribution measured by the measuring means is excessive, the viscosity coefficient of the lava flow is decreased with respect to the value at the start of the calculation, and the volume flow rate of the lava flow predicted by the analyzing means is If the lava flow thickness distribution calculated by the calculating means is greater than or equal to the volumetric flow rate of the lava flow and is less than the lava flow thickness distribution measured by the measuring means, the lava flow A volcanic lava flow prediction system that increases the viscosity coefficient relative to the value at the start of calculation and recalculates the area where the lava flow reaches. In claim 1, 2 or 3,
After the start of calculation by the analysis means, the volume flow of the lava flow predicted by the analysis means is equal to or less than the volume flow of the lava flow calculated by the calculation means, and the lava flow thickness distribution predicted by the analysis means is When the lava flow thickness distribution is too large compared to the measured lava flow thickness distribution, the lava flow temperature is increased with respect to the value at the start of the calculation, and the volume flow rate of the lava flow predicted by the analyzing means is calculated. If the lava flow thickness distribution calculated by the means is greater than or equal to the volumetric flow rate of the lava flow and the lava flow thickness distribution predicted by the analysis means is less than the lava flow thickness distribution measured by the measurement means, the lava flow temperature The volcanic lava flow prediction system is characterized in that the area where the lava flow reaches is recalculated by reducing the value to the value at the start of the calculation. In claim 1, 2 or 3,
The measuring means has a distance measuring device that measures the arrival area of the lava flow using an electromagnetic wave or optics from an aircraft, a communication satellite, or the ground, and the absolute coordinates including the latitude, longitude, and altitude of these distance measuring devices are determined by the satellite. A volcanic lava flow prediction system that is determined by radio waves from a position measurement system (GPS) and measures the latitude and longitude of the boundary of the area where the lava flow reaches. In claim 1, 2 or 3,
Generate initial values including the above-mentioned topographical distribution, reach area of the measured lava flow, reached lava flow thickness distribution and temperature distribution, and the crater position, volumetric flow rate or mass flow rate of lava flow, temperature or ratio Input data generation calculation module that generates boundary values including enthalpy, analysis calculation module that predicts the arrival area of the lava flow by inputting the initial value and the boundary condition, and displays the predicted arrival area of the lava flow A volcanic lava flow prediction system comprising a computer having display means. In claim 10,
The said display means is a volcanic lava flow prediction system characterized by comparing and displaying the present arrival area of the lava flow and the expected arrival area of the lava flow after a predetermined time.

Images