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Subterranean Rumbling
Subterranean rumbling is a phenomenon in which the ground vibrates and makes sounds due to an earthquake. During earthquakes or volcanic eruptions, the ground vibrates, sometimes creating short-period seismic wave motion (ground motion) that reaches the air and becomes sounds (sound waves), and low sounds can be heard.Tokuji Utsu『地震学 第3版』P.308 This often occurs during shallow-focus earthquakes and earthquake swarms. Even microearthquakes that produce noticeable tremors can sometimes produce rumbling. Hard ground tends to amplify rumbling. In earthquake-prone Japan rumbling is frequently observed near Mt. Tsukuba in Ibaraki Prefecture. This is believed to be due to local exposure of basement rocks. During the 1965 Matsushiro earthquake swarm The Matsushiro earthquake swarm () was an earthquake swarm that occurred near Matsushiro, a suburb of Nagano, to the northwest of Tokyo in 1965. The event is one of the best ever documented earthquake swarms. Overvi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sounds
In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the brain. Only acoustic waves that have frequencies lying between about 20 Hz and 20 kHz, the audio frequency range, elicit an auditory percept in humans. In air at atmospheric pressure, these represent sound waves with wavelengths of to . Sound waves above 20 kHz are known as ultrasound and are not audible to humans. Sound waves below 20 Hz are known as infrasound. Different animal species have varying hearing ranges. Acoustics Acoustics is the interdisciplinary science that deals with the study of mechanical waves in gasses, liquids, and solids including vibration, sound, ultrasound, and infrasound. A scientist who works in the field of acoustics is an ''acoustician'', while someone working in the field of acoustical e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earthquake
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from those that are so weak that they cannot be felt, to those violent enough to propel objects and people into the air, damage critical infrastructure, and wreak destruction across entire cities. The seismic activity of an area is the frequency, type, and size of earthquakes experienced over a particular time period. The seismicity at a particular location in the Earth is the average rate of seismic energy release per unit volume. The word ''tremor'' is also used for Episodic tremor and slip, non-earthquake seismic rumbling. At the Earth's surface, earthquakes manifest themselves by shaking and displacing or disrupting the ground. When the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Eruptions
Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed. Some volcanoes may exhibit only one characteristic type of eruption during a period of activity, while others may display an entire sequence of types all in one eruptive series. There are three different types of eruptions: * Magmatic eruptions are the most well-observed type of eruption. They involve the decompression of gas within magma that propels it forward. * Phreatic eruptions are driven by the superheating of steam due to the close proximity of magma. This type exhibits no magmatic release, instead causing the granulation of existing rock. * Phreatomagmatic eruptions are driven by the direct interaction of magma and water, as opposed to phreatic erupt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ground Motion
Ground motion is the movement of the earth's surface from earthquakes or explosions. Ground motion is produced by seismic waves that are generated by sudden slip on a fault or sudden pressure at the explosive source and travel through the earth and along its surface. This can be due to natural events, such as earthquakes and volcanic eruptions, or human activities, such as the detonation of nuclear weapons. There are two main types of seismic waves: body waves and surface waves. Body waves travel through the interior of the earth, while surface waves travel along the earth's surface. Ground motion is typically caused by surface waves, which are the most destructive type of seismic waves. Ground motion is measured using a seismometer, a device that detects and records the movement of the earth's surface. Seismometers are used by seismologists to study earthquakes and other types of ground motion. The recordings produced by a seismometer are known as seismograms, and they can be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sound Waves
In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the brain. Only acoustic waves that have frequencies lying between about 20 Hz and 20 kHz, the audio frequency range, elicit an auditory percept in humans. In air at atmospheric pressure, these represent sound waves with wavelengths of to . Sound waves above 20 kHz are known as ultrasound and are not audible to humans. Sound waves below 20 Hz are known as infrasound. Different animal species have varying hearing ranges. Acoustics Acoustics is the interdisciplinary science that deals with the study of mechanical waves in gasses, liquids, and solids including vibration, sound, ultrasound, and infrasound. A scientist who works in the field of acoustics is an ''acoustician'', while someone working in the field of acoust ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tokuji Utsu
Tokuji Utsu (, April 13, 1928 - August 18, 2004) was a Japanese seismologist and Professor Emeritus of University of Tokyo. He graduated from the Faculty of Science at the University of Tokyo in 1951 and became a professor at the Earthquake Research Institute, University of Tokyo in 1977. Utsu was compiling "Catalog of Damaging Earthquakes in the World". He is recipients of the Medal with Purple Ribbon, the Order of the Sacred Treasure, 2nd class and so on. Books * 宇津徳治 『地震学』 共立出版〈共立全書〉(1977) * 宇津徳治 『地震学 第2版』 共立出版〈共立全書〉(1984) * 宇津徳治ほか編 『地震の事典』 朝倉書店 (1987) * 宇津徳治 『世界の被害地震の表 - 暫定版』 Earthquake Research Institute, University of Tokyo (1989) * 宇津徳治 『日本付近のM6.0以上の地震および被害地震の震度分布図 - 1901年～1926年』Earthquake Research Institute, University of Tokyo (1989年) * 宇津徳治 『� ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shallow-focus Earthquake
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from those that are so weak that they cannot be felt, to those violent enough to propel objects and people into the air, damage critical infrastructure, and wreak destruction across entire cities. The seismic activity of an area is the frequency, type, and size of earthquakes experienced over a particular time period. The seismicity at a particular location in the Earth is the average rate of seismic energy release per unit volume. The word ''tremor'' is also used for non-earthquake seismic rumbling. At the Earth's surface, earthquakes manifest themselves by shaking and displacing or disrupting the ground. When the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause a tsunami. Earthquakes ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earthquake Swarms
In seismology, an earthquake swarm is a sequence of seismic events occurring in a local area within a relatively short period. The time span used to define a swarm varies, but may be days, months, or years. Such an energy release is different from the situation when a major earthquake (main shock) is followed by a series of aftershocks: in earthquake swarms, no single earthquake in the sequence is obviously the main shock. In particular, a cluster of aftershocks occurring after a mainshock ''is not'' a swarm. History and generalities In the Ore Mountains (Erzgebirge), which form the border between the Czech Republic and Germany, western Bohemia and the Vogtland region, have been known since the 16th century as prone to frequent earthquake swarms, which typically last a few weeks to a few months. Austrian geologist Josef Knett, while studying in 1899 a swarm of about a hundred events felt in western Bohemia/Vogtland in January-February 1824, coined the noun ''Schwarmbeben'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microearthquake
A microearthquake (or microquake) is a very low intensity earthquake which is 2.0 or less in magnitude. They are very rarely felt beyond from their epicenter. In addition to having natural tectonic causes, they may also be seen as a result of underground nuclear testing or even large detonations of conventional explosives for producing excavations. They normally cause no damage to life or property, and are very rarely felt by people. Microquakes occur often near volcanoes as they approach an eruption, and frequently in certain regions exploited for geothermal energy , such as near Geyserville in Northern California Northern California (colloquially known as NorCal) is a geographic and cultural region that generally comprises the northern portion of the U.S. state of California. Spanning the state's northernmost 48 counties, its main population centers incl .... These occur so continuously that thcurrent USGS event map for that locationusually shows a substantial number of small ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north toward the East China Sea, Philippine Sea, and Taiwan in the south. Japan is a part of the Ring of Fire, and spans an archipelago of 6852 islands covering ; the five main islands are Hokkaido, Honshu (the "mainland"), Shikoku, Kyushu, and Okinawa. Tokyo is the nation's capital and largest city, followed by Yokohama, Osaka, Nagoya, Sapporo, Fukuoka, Kobe, and Kyoto. Japan is the eleventh most populous country in the world, as well as one of the most densely populated and urbanized. About three-fourths of the country's terrain is mountainous, concentrating its population of 123.2 million on narrow coastal plains. Japan is divided into 47 administrative prefectures and eight traditional regions. The Greater Tokyo Ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ibaraki Prefecture
is a prefecture of Japan located in the Kantō region of Honshu. Ibaraki Prefecture has a population of 2,871,199 (1 June 2019) and has a geographic area of . Ibaraki Prefecture borders Fukushima Prefecture to the north, Tochigi Prefecture to the northwest, Saitama Prefecture to the southwest, Chiba Prefecture to the south, and the Pacific Ocean to the east. Mito, the capital, is the largest city in Ibaraki Prefecture. Other major cities include Tsukuba, Hitachi, and Hitachinaka. Ibaraki Prefecture is located on Japan's eastern Pacific coast to the northeast of Tokyo, and is part of the Greater Tokyo Area, the most populous metropolitan area in the world. Ibaraki Prefecture features Lake Kasumigaura, the second-largest lake in Japan; the Tone River, Japan's second-longest river and largest drainage basin; and Mount Tsukuba, one of the most famous mountains in Japan. Ibaraki Prefecture is also home to Kairaku-en, one of the Three Great Gardens of Japan, and is a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basement Rocks
In geology, basement and crystalline basement are crystalline rocks lying above the mantle and beneath all other rocks and sediments. They are sometimes exposed at the surface, but often they are buried under miles of rock and sediment. The basement rocks lie below a sedimentary platform or cover, or more generally any rock below sedimentary rocks or sedimentary basins that are metamorphic or igneous in origin. In the same way, the sediments or sedimentary rocks on top of the basement can be called a "cover" or "sedimentary cover". Crustal rocks are modified several times before they become basement, and these transitions alter their composition. Continental crust Basement rock is the thick foundation of ancient, and oldest, metamorphic and igneous rock that forms the crust of continents, often in the form of granite. Basement rock is contrasted to overlying sedimentary rocks which are laid down on top of the basement rocks after the continent was formed, such as sandstone and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
