Abstract: A tornado warning system having means for monitoring seismic waves of a predetermined frequency range including long-period seismic waves and short-period seismic waves. The seismic waves are associated with and produced in the ground as a result of an approaching tornado. The warning system comprises means for detecting the seismic waves including the long-period seismic waves and the short-period seismic waves and for providing an electrical output indicative thereof. Circuit means are provided for processing the electrical output to provide an output signal indicative of the long-period seismic waves and the short-period seismic waves. Alarm means are provided for receiving the output signal from the circuit means to generate an alarm to warn of the presence of a tornado.

Abstract: A method of determining whether a structure such as a bridge has been severely damaged by an earthquake or other disturbance such as a flood. The method is designed to be carried out by unsophisticated persons immediately after such disturbance so that unnecessary delays will not be caused by the closing of bridges and the like which are not severely damaged. The method involves affixing a target to one portion of the structural member such as a span and affixing a pointer on another structural member such as a column. Preferably the target and pointer are positioned in such a way that a safe or unsafe determination can be easily made by the viewer.

Abstract: A method and system for using sonography to image the internal structure of geophysical and geologic models are disclosed. The sonography system includes a wand having a plurality of piezoelectric elements at an active surface thereof, each coupled to driver/receiver circuitry. Certain of the piezoelectric elements are selected as ultrasonic sources and receivers; the source/receiver designation may vary over time, as each of the elements may either generate or receive acoustic energy. A computer system, connected to the wand, receives signals from the receivers corresponding to reflected and refracted ultrasonic energy, and generates a zero offset trace image therefrom. In the geophysical case, the scale model is formed of materials such as plastics and rubbers having the desired properties for simulating the response of a portion or layer in the earth to ultrasonic vibrations.

Abstract: A method and apparatus for detecting the seismic signal generated by a tornado and providing timely warning of the tornado's approach. The invention involves the use of a geophone or velocity transducer (3) to detect the seismic surface waves generated by the tornado. The output of the geophone passes to the microchip (4) installed with the alarm system (5) within the building (6). Within the microchip the signal passes through the A/D converter (7), to the band-pass filter (8), and then to the signal-to-noise comparator (9). When the signal-to-noise ratio exceeds a specified level, the switch (10) is closed and the alarm (5) is activated.

Abstract: A seismographic sensor is constructed from a D'Arsonval movement. The elements of the movement include a coil suspended in the field of a permanent magnet and a pointer attached to the coil. A weight is attached to the pointer and acts as an inertia element. Leveling screws are provided to control the period of the weighted pointer and to control the resting position of the pointer. When the base of the meter vibrates during an earthquake, the weighted pointer does not follow the vibration because of its inertia, resulting in a relative rotation of the meter coil and the magnet field, thereby inducing a voltage in the coil. This voltage is proportional to one component of horizontal velocity of the earth's motion. Means are provided to process and record the magnitude of this voltage.

Abstract: This is an apparatus for measuring the intensity of a seismic shock applied to the apparatus. The apparatus includes an enclosure in which is a system of weights movable in response to an applied mechanical shock, and connected to a movable transmission member. The transmission member contacts a first spiral cam rotatably mounted on a balanced rockable lever. The cam turns the lever angularly when the transmission member is moved by the weights. A spring connected to the lever tends to inhibit it from turning out of its balanced position when the transmission member moves. A second spiral cam is also rotatably mounted on the lever. A fixed stop member contacts the second cam to prevent the lever from turning back to its original balanced position when the lever is turned out of this position in response to an applied mechanical shock. An index needle connected to the lever indicates on a scale the amount that the lever has turned.

Abstract: Two sector-shaped pendulums are supported by crossed leaf springs at two axes on the same horizontal level respectively in a symmetrical manner so that each pendulum can swing about the axis thereof, sector-shaped surfaces of the pendulums being connected to each other by mutually-crossing flexible wires, each pendulum having a movable weight and a rigid extension so that a coiled spring connects the rigid extensions of the two pendulums, and each pendulum has a means for adjusting the center of gravity thereof by moving said weight and for adjusting the location of joints of said coiled spring.

Abstract: An alarm system is provided for detecting a seismic tremor and for generating an audio and/or visual alarm signal which varies depending upon the magnitude of the seismic tremor. In the preferred form of the invention, the alarm system comprises a free running oscillator having a pair of terminals the capacitive value across which controls the frequency of the oscillator. A fixed oscillator plate is electrically connected to one terminal while a variable position oscillator plate is electrically connected to the other terminal and has an inertial mass secured to it. A spring positioned between the plates urges the variable position capacitor plate away from the fixed plate but still enables the variable position capacitor plate to move in response to a seismic tremor thus varying the capacitive value between the terminals and the frequency of the oscillator. The output from the oscillator is coupled through a phase locked loop circuit which tracks the oscillator output.

Abstract: A device for measuring distances is provided wherein, after calibration of the device, a cursor mounted on an elongate movable wand is moved to the point whose distance from a datum point is to be determined. A resistor extends along the length of the wand and an electrical contact on the cursor makes point contact with the resistor. The contact and resistor form a potentiometer whose output varies directly with the position of the cursor. A digital voltmeter connected to the output of the potentiometer provides an indication of the distance measured.

Abstract: The present invention relates to a model, and the making of such model, of subsurface features of the earth, utilizing a plurality of processed seismic sections spaced apart in a manner representing the disposition of the seismic profiles along seismic survey lines from which they came. The technique facilitates the making of interpretive geological judgements, and is of particular utility when direct indications of hydrocarbons exist.