JPH0369077B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a geological exploration method and exploration device useful for exploring faults, cracks, warm water veins, etc.

[Prior art] This type of geological exploration generally includes radioactivity exploration,
Methods such as elastic wave exploration and electrical exploration are known.
However, these methods not only require special techniques and skill, but also have problems with the exploration data collection means themselves, and no method that is sufficient for practical use has yet been established. In other words, while walking exploration is an ideal means of collecting data, it is undeniably inefficient and has its own operational limitations due to terrain. Although vehicle exploration is more efficient than walking, it is limited to situations where the terrain is approximately flat, and is unsuitable for terrain with large undulations or obstacles. In addition, when using a flying vehicle such as a helicopter, the physical constraints on data collection that are imposed by walking exploration or vehicle exploration are eliminated, and combined with its high efficiency, it can be said to be an extremely preferable method, but the distance from the ground is large. This is undeniable, and as a result, the measurement data lacks accuracy, making it difficult to achieve the intended purpose. From this perspective, various exploration methods using flying vehicles have been studied, but no practical technology system has yet been established.

[Problems to be Solved by the Invention] The present invention relates to a practical geological exploration method using aerial measurements, which uses an aircraft, especially a helicopter, to measure gamma rays, ground surface altitude, and ground surface temperature. Based on the analysis of the measurement data of
To provide an exploration method and device that can automatically locate locations where cracks and warm water veins may exist.

[Means for Solving the Problems] The present inventor has determined the gamma rays of the energy range of each nuclide, flight altitude, ground altitude, ground surface temperature, ground speed, and flight As a result of the measurement of time, etc., the rate of change of the terrain slope (tanθ), which is calculated by dividing the time difference height of the ground surface altitude obtained by subtracting the ground altitude from the flight altitude by the product of ground speed and flight time, and the ground surface temperature. By using the rate of temperature change obtained by dividing the time difference value by the product of ground speed and flight time, it is possible to know the possible locations of faults and cracks based on their appearance, and the possibility of the presence or absence of surface water and underground water. I found it. In other words, faults and cracks are likely to exist in places where the rate of change in topographical slope is large, and in places where surface water or underground water exists, the ground surface temperature differs by several degrees compared to the surrounding area. The present invention can be a means for determining whether the existence of possible faults/cracks extracted from this topographical data is also supported by internal factors, and specifically Compared to the count ratio of the radon daughter element of gamma rays and potassium, which is ²¹⁴ Bi/ ⁴⁰ K, this ratio is usually more than double near faults, and the presence of surface water and underground water causes the ground surface temperature to increase. changes by more than a few degrees from the surrounding area, and in geothermal areas, the count ratio of thoron daughter elements and radon daughter elements
Judgment is based on the criteria that ²⁰⁸ Tl/ ²¹⁴ Bi has decreased to 80% or less of the normal zone.

^The radioactive elements Raun ^-208 U, Thorium ^{- 232} Th ^, and Potassium ^{- 40} K found in rocks emit radiation and decay into stable elements. During this period, the higher the ground temperature, the higher the pressure of radon gas and thoron gas.
Gas migration occurs along the crack. However, the half-life of radon is 3.825 days, while the half-life of thoron is 54.5 seconds, so there is a large difference between them, so the ratio between the elements changes due to movement. Therefore, if there are cracks in the ground, the separation of radioactive elements progresses, and the ratio of ²³⁸ U series gamma rays and ²³² Th series gamma rays to the ⁴⁰ K series gamma ray dose increases relatively. District ²³² Th
The ratio of the gamma ray dose of the series to the gamma ray dose of the ²³⁸ U series becomes relatively low. Faults, cracks, etc. are generally exposed on the ground at topographic slope transformation lines, valley bottoms, and ridgelines, but in these areas, the gamma dose ratio of ^{the 40} K series/ ²³⁸ U series and ^{the 40} K series/238 U series
When the gamma dose ratio of the ²³² Th series is relatively low, the presence of faults, cracks, and underground water veins is predicted, and when the gamma dose ratio of ^{the 238} U series/ ²³² Th series is relatively high, it is predicted that geothermal If the gamma dose ratio of ^{the 40} K series/ ²³⁸ U series is relatively low and the gamma dose ratio of ^{the 238} U series/ ²³² Th series is relatively high, the existence of hot spring veins can be predicted. let The present invention is characterized by searching for faults, cracks, and warm water veins from topographic gradient conversion lines, valley bottoms, or ridgelines where the dose ratio of gamma rays in different energy bands shows a relatively abnormal change.

DESCRIPTION OF THE EMBODIMENTS FIG. 1 shows a schematic block diagram of equipment installed on a helicopter for carrying out the invention. 10
is a detector consisting of a scintillator and a pulse height analyzer for environmental gamma rays, 12 is a detector for ⁴⁰ K series gamma rays, 14 is a detector for ²³⁸ U series gamma rays, and 16 is a detector for ²³² Th series gamma rays. It is a vessel. The output of each detector 10-16 is logarithmized by a logarithmization circuit 18-24, respectively. The output of the logarithmization circuit 20 and the output of the logarithmization circuit 22 are subtracted by a subtraction circuit 26. Subtraction circuit 26
The output shows the ratio of the gamma dose of ^{the 40} K series to the gamma dose of ^{the 238} U series. Similarly, the subtraction circuit 28
calculates the difference between the output of the logarithmization circuit 20 and the output of the logarithmization circuit 24, and the subtraction circuit 30 calculates the difference between the output of the logarithmization circuit 22 and the output of the logarithmization circuit 24. In addition, 32 radio altimeters, 3 barometric altimeters
4. Load the speedometer 36 and radiation thermometer 38.
Data from these are utilized to calculate the rate of change of terrain slope and rate of temperature change described above. Detector 10 for environmental gamma rays is used to monitor object and background effects.

Output of logarithmization circuit 18, subtraction circuits 26, 28,
30 and the outputs of devices 32, 34, 36, 38 are supplied to an arithmetic circuit 40. Arithmetic circuit 40
calculates whether or not the corresponding conditions are satisfied for each of the above-mentioned judgment factors, outputs an output when necessary, and activates the alarm member 42. The alarm member 42 notifies the measurer of the discovery of a hot spring vein, for example, by means of light or sound. Further, the outputs of these devices 18, 26 to 38 are recorded in a data recorder 44 for precise analysis on the ground.

In order to easily confirm the relevant area later, it is preferable to record visible light images and thermal infrared images of the gamma ray exploration area on a video tape recorder in synchronization with this gamma ray measurement.

Although not shown in FIG. 1, this analysis device includes each gamma ray detector 10 to 16 and an arithmetic circuit 4.
A clock circuit is provided which operates the 0, etc. in synchronization and also determines the data sampling time or period.

Figure 2 is a graph of measurement data regarding hot spring veins. The horizontal axis indicates flight time or flight distance. The upper part of the graph shows flight altitude H, ground altitude △h, and ground surface altitude H-△h on the normal vertical axis scale, and the lower part shows environmental gamma rays (ch1), 40K series gamma rays (ch2), and ²³⁸ U series gamma rays. (ch3) and ²³² Th series gamma rays (ch4) are shown on the vertical axis logarithmic scale. The area indicated by the upward arrow is a valley, and the gamma ray dose ratio of ²³⁸ U series and ²³² Th series is significantly large, suggesting the existence of hot spring veins.

Specifically, a small and inexpensive personal computer can be used as the arithmetic circuit 40. Therefore, the maximum value, minimum value, average value, etc. of each sampling value of data from each device can be recorded as appropriate. By incorporating programming and software, it is possible to easily discover changes in gamma ray doses in each energy band. That is, the arithmetic circuit 40 of this embodiment is capable of controlling the count ratio of radon daughter elements and potassium when the topographic slope (tanθ) changes by more than twice.
When ²¹⁴ Bi/ ⁴⁰ K changes more than twice, the fault
Indicates that there is a high possibility that a crack exists. The slope of the terrain has more than doubled, and the sign of the slope has changed,
Radon daughter element and potassium count ratio ²¹⁴ Bi/
⁴⁰ K changes by more than twice and the ground surface temperature changes by several degrees Celsius or more, when the count ratio of thoron daughter elements and radon daughter elements ²⁰⁸ Tl/ ²¹⁴ Bi decreases, it is possible that hot spring veins exist. On the other hand, when ²⁰⁸ Tl/ ²¹⁴ Bi increases, it indicates that there is a high possibility that a groundwater vein exists. In these significant situations, the arithmetic circuit 40 outputs an alarm signal to the alarm member 42. XY Pro Tsutaya
When using a CRT, a predetermined alarm signal is output on plotter paper or on the CRT.

When collecting data, the flight altitude, ground altitude, and ground speed are usually input into the data recorder every second, so the relationship between the flight distance and the ground surface altitude can be determined, and as a result, the terrain cross section is input into the data recorder. It will be done. At the same time, since the ground surface temperature is also input to the data recorder by the radiation thermometer 38, it is possible to grasp how the ground surface temperature changes in response to changes in land use. In places with a lot of moisture on the ground, and in valley bottoms with surface water and underground water, the temperature is several degrees different from the surrounding area (higher in winter and lower in summer), so this data is linked with topographic cross-section data. If the aircraft flies at a speed of 90km/h, it will be able to detect the presence of water that serves as a reservoir for groundwater and hot spring water at intervals of approximately 25m.

In addition, in the present invention, the number of counts of airborne gamma rays corresponding to each nuclide is normally measured for 5 seconds, which means that when flying at 90 km per hour, airborne gamma rays are measured at intervals of 125 m on the ground surface. ,
The aircraft normally flies at an altitude of 100m above the ground, so it measures 90% of the radiation emitted from a 500m diameter area above the ground.

In addition, this exploration device can shorten the data collection time to 0.5 seconds, and by taking the cumulative sum of 5 seconds to 0.5 seconds, the ground resolution can be increased to 12.5 meters when flying at 90 km/hour.

In order to automatically analyze faults, cracks, and warm water veins in a planar manner according to the present invention, the topographical information, ground surface temperature information, and gamma ray information recorded in the data recorder 44 are processed on the ground, and the faults are displayed on a plotter or CRT.・It is sufficient to display two-dimensionally the locations where cracks and warm water veins are likely to exist. This program except that it also processes probe position data.
It is basically the same as the operation program of the arithmetic circuit 40.

[Effects of the Invention] According to the present invention, by processing airborne gamma rays and various types of flight information, it is possible to immediately locate locations where faults, cracks, and warm water veins are likely to exist, or by using a plotter or CRT. It can be discovered two-dimensionally, and no special knowledge or skill is required to make that determination.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of an apparatus for implementing the present invention, and FIG. 2 is a graph showing an example of measurement data. 10, 12, 14, 16... Gamma ray detector, 1
8, 20, 22, 24...logarithmization circuit, 26, 2
8, 30... Subtraction circuit, 32... Radio altimeter, 34...
Barometric altimeter, 36... speedometer, 38... radiation thermometer,
40...Arithmetic circuit, 42...Alarm member, 44...Data recorder.

Claims (1)

[Claims] 1. A gamma ray detection member loaded on a flying object,
In addition to measuring multiple gamma ray doses in different energy bands from the exploration target area, we also measure the ground surface altitude and ground surface temperature, and calculate the rate of change in topographical slope determined from the ground surface altitude.
A geological exploration method by aerial measurement of gamma rays, characterized in that the geology is explored from the rate of change in ground surface temperature and the rate of change in the dose ratio for each energy band of the measured gamma rays. 2. The method according to claim 1, wherein the gamma rays include at least ⁴⁰ K series gamma rays, ²³⁸ U series gamma rays, and ²³² Th series gamma rays. 3. Claim 1, characterized in that the rate of change in terrain slope is a value obtained by dividing the time difference height of the ground surface altitude obtained by subtracting the ground altitude from the flight altitude by the product of ground speed and flight time. Method described. 4. The method according to claim 1, wherein the rate of change of the ground surface temperature is a value obtained by dividing the time difference value of the ground surface temperature by the product of ground speed and flight time. 5. When the topographic slope changes by more than twice and the count ratio of radon daughter element and potassium ²¹⁴ Bi / ⁴⁰ K changes by more than twice, it indicates the existence of a fault/fissure, and the topographic slope changes by more than twice. , the sign of the slope changes, and the count ratio of radon daughter element and potassium
When ²¹⁴ Bi/ ⁴⁰ K changes by more than twice, the ground surface temperature changes by several degrees Celsius or more, and the count ratio of thoron daughter elements and radon daughter elements ²⁰⁸ Tl/ ²¹⁴ Bi decreases, this indicates the existence of hot spring veins. , the topographical slope changed by more than twice, the sign of the slope changed, and the count ratio of radon daughter elements and potassium changed.
When ²¹⁴ Bi/ ⁴⁰ K changes by more than double, the ground surface temperature changes by several degrees Celsius or more, and the count ratio of thoron daughter elements and radon daughter elements ²⁰⁸ Tl/ ²¹⁴ Bi increases, it indicates the presence of underground water veins. A method according to claim 2, characterized in that: 6 A flying vehicle; at least three gamma ray detectors with different detection energy bands loaded on the flying vehicle; a component loaded on the flying vehicle to measure the ground surface altitude of the measurement area; a member that measures the ground surface temperature in the measurement area, a ratio calculation member that obtains a signal indicating the ratio between each output of the gamma ray detector, and the output of the ratio calculation member, the ground surface altitude data, and the ground surface temperature. It is characterized by comprising an arithmetic circuit that generates a predetermined alarm signal when these indicate a predetermined change based on data, and an alarm member that generates a predetermined alarm in response to the output of the arithmetic circuit. A geological exploration device that uses gamma ray aerial measurements. 7. Claim 6, wherein the gamma rays include at least ⁴⁰ K series gamma rays, ²³⁸ U series gamma rays, and ²³² Th series gamma rays.
The equipment described in section. 8. When the topographical slope changes by more than twice and the count ratio of radon daughter elements and potassium changes by more than twice, the arithmetic circuit indicates the existence of ^a fault/ ^fissure , and the topographical slope changes by more than twice. It changes more than twice, the sign of the slope changes, and the count ratio of radon daughter element and potassium changes.
When ²¹⁴ Bi/ ⁴⁰ K changes by more than twice, the ground surface temperature changes by several degrees Celsius or more, and the count ratio of thoron daughter elements and radon daughter elements ²⁰⁸ Tl/ ²¹⁴ Bi decreases, this indicates the existence of hot spring veins. , the topographical slope changed by more than twice, the sign of the slope changed, and the count ratio of radon daughter elements and potassium changed.
When ²¹⁴ Bi/ ⁴⁰ K changes by more than twice, the ground surface temperature changes by several degrees Celsius or more, and the count ratio of thoron daughter elements and radon daughter elements ²⁰⁸ Tl/ ²¹⁴ Bi increases, it indicates the presence of underground water veins. 8. A device according to claim 7, characterized in that: 9. The device according to any one of claims 6 to 8, wherein the ground surface height measuring member obtains the ground surface height from measured values of flight altitude and ground altitude.