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120-867: The earthquake had a magnitude of 7.9 on the moment magnitude scale (M w  ), with its focus deep beneath Izu Ōshima Island in Sagami Bay . The cause was a rupture of part of the convergent boundary where the Philippine Sea plate is subducting beneath the Okhotsk microplate along the line of the Sagami Trough . In the immediate aftermath of the earthquake, the Kantō Massacre began. Rumors emerged that ethnic Koreans in Japan had poisoned wells or were planning to attack cities. In response,

240-403: A debris flow or mud flow . However, also dry debris can exhibit flow-like movement. Flowing debris or mud may pick up trees, houses and cars, and block bridges and rivers causing flooding along its path. This phenomenon is particularly hazardous in alpine areas, where narrow gorges and steep valleys are conducive of faster flows. Debris and mud flows may initiate on the slopes or result from

360-628: A Buddhist-style memorial hall/museum, a memorial bell donated by Taiwanese Buddhists, a memorial to the victims of World War II Tokyo air raids , and a memorial to the Korean victims of the vigilante killings. In the historical fantasy novel Teito Monogatari ( Hiroshi Aramata ) a supernatural explanation is given for the cause of the Great Kantō earthquake, connecting it with the principles of feng shui . In Yasunari Kawabata 's 1930 novel The Scarlet Gang of Asakusa several chapters deal with

480-416: A body-wave magnitude scale ( mB ) by Gutenberg and Richter in 1956, and a number of variants – to overcome the deficiencies of the M L   scale, but all are subject to saturation. A particular problem was that the M s   scale (which in the 1970s was the preferred magnitude scale) saturates around M s  8.0 and therefore underestimates the energy release of "great" earthquakes such as

600-504: A constant term ( W 0 / M o  = 5 × 10 ) in Eq. (A) and estimated M s and denoted as M w (dyn.cm). The energy Eq. (A) is derived by substituting m  = 2.5 + 0.63 M in the energy equation Log E  = 5.8 + 2.4 m (Richter 1958), where m is the Gutenberg unified magnitude and M is a least squares approximation to the magnitude determined from surface wave magnitudes. After replacing

720-465: A culture of militarism . After the earthquake, Gotō Shinpei organized a reconstruction plan of Tokyo with modern networks of roads, trains, and public services. Parks were placed all over Tokyo as refuge spots, and public buildings were constructed with stricter standards than private buildings to accommodate refugees. The outbreak of World War II and subsequent destruction severely limited resources. Frank Lloyd Wright received credit for designing

840-466: A depth from few decimeters to some meters) is called a shallow landslide. Debris slides and debris flows are usually shallow. Shallow landslides can often happen in areas that have slopes with high permeable soils on top of low permeable soils. The low permeable soil traps the water in the shallower soil generating high water pressures. As the top soil is filled with water, it can become unstable and slide downslope. Deep-seated landslides are those in which

960-403: A distance of approximately 100 to 600 km (62 to 373 mi), conditions where the surface waves are predominant. At greater depths, distances, or magnitudes the surface waves are greatly reduced, and the local magnitude scale underestimates the magnitude, a problem called saturation . Additional scales were developed – a surface-wave magnitude scale ( M s ) by Beno Gutenberg in 1945,

1080-500: A double couple, but not from a single couple. This was confirmed as better and more plentiful data coming from the World-Wide Standard Seismograph Network (WWSSN) permitted closer analysis of seismic waves. Notably, in 1966 Keiiti Aki showed that the seismic moment of the 1964 Niigata earthquake as calculated from the seismic waves on the basis of a double couple was in reasonable agreement with

1200-418: A general solution in 1964 by Burridge and Knopoff, which established the relationship between double couples and the theory of elastic rebound, and provided the basis for relating an earthquake's physical features to seismic moment. Seismic moment – symbol M 0   – is a measure of the fault slip and area involved in the earthquake. Its value is the torque of each of the two force couples that form

1320-544: A low shearing resistance. On the slopes, some earthflow may be recognized by their elongated shape, with one or more lobes at their toes. As these lobes spread out, drainage of the mass increases and the margins dry out, lowering the overall velocity of the flow. This process also causes the flow to thicken. Earthflows occur more often during periods of high precipitation, which saturates the ground and builds up water pressures. However, earthflows that keep advancing also during dry seasons are not uncommon. Fissures may develop during

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1440-407: A portable radio and use it to listen to reliable information, and not to be misled by rumors in the event of a large earthquake. Following the devastation of the earthquake, some in the government considered the possibility of moving the capital elsewhere. Proposed sites for the new capital were even discussed. Japanese commentators interpreted the disaster as an act of divine punishment to admonish

1560-402: A portion Δ W {\displaystyle \Delta W} of this stored energy is transformed into The potential energy drop caused by an earthquake is related approximately to its seismic moment by where σ ¯ {\displaystyle {\overline {\sigma }}} is the average of the absolute shear stresses on the fault before and after

1680-530: A reconstruction of the evolution of a particular landslide. Therefore, landslide hazard mitigation measures are not generally classified according to the phenomenon that might cause a landslide. Instead, they are classified by the sort of slope stabilization method used: Climate-change impact on temperature, both average rainfall and rainfall extremes, and evapotranspiration may affect landslide distribution, frequency and intensity (62). However, this impact shows strong variability in different areas (63). Therefore,

1800-532: A reference point and the ten-fold (exponential) scaling of each degree of magnitude, and in 1935 published what he called the "magnitude scale", now called the local magnitude scale , labeled M L  . (This scale is also known as the Richter scale , but news media sometimes use that term indiscriminately to refer to other similar scales.) The local magnitude scale was developed on the basis of shallow (~15 km (9 mi) deep), moderate-sized earthquakes at

1920-585: A result of large fires that broke out. Fires started immediately after the earthquake. Some fires developed into firestorms that swept across cities. Many people died when their feet became stuck on melting tarmac . The single greatest loss of life was caused by a fire whirl that engulfed the Rikugun Honjo Hifukusho (formerly the Army Clothing Depot) in downtown Tokyo, where about 38,000 people who had taken shelter there during

2040-443: A segment recounting Tokyo's devastation 100 years prior. Moment magnitude scale The moment magnitude scale ( MMS ; denoted explicitly with M or M w   or Mwg , and generally implied with use of a single M for magnitude ) is a measure of an earthquake 's magnitude ("size" or strength) based on its seismic moment . M w   was defined in a 1979 paper by Thomas C. Hanks and Hiroo Kanamori . Similar to

2160-449: A single couple model. In principle these models could be distinguished by differences in the radiation patterns of their S-waves , but the quality of the observational data was inadequate for that. The debate ended when Maruyama (1963), Haskell (1964), and Burridge and Knopoff (1964) showed that if earthquake ruptures are modeled as dislocations the pattern of seismic radiation can always be matched with an equivalent pattern derived from

2280-542: A slope prone to failure. In many cases, the landslide is triggered by a specific event (such as a heavy rainfall , an earthquake , a slope cut to build a road, and many others), although this is not always identifiable. Landslides are frequently made worse by human development (such as urban sprawl ) and resource exploitation (such as mining and deforestation ). Land degradation frequently leads to less stabilization of soil by vegetation . Additionally, global warming caused by climate change and other human impact on

2400-439: A three-decade-long controversy over the best way to model the seismic source: as a single couple, or a double couple. While Japanese seismologists favored the double couple, most seismologists favored the single couple. Although the single couple model had some shortcomings, it seemed more intuitive, and there was a belief – mistaken, as it turned out – that the elastic rebound theory for explaining why earthquakes happen required

2520-430: A very wide range, from as low as 1 mm/yr to many km/h. Though these are a lot like mudflows , overall they are more slow-moving and are covered with solid material carried along by the flow from within. Clay, fine sand and silt, and fine-grained, pyroclastic material are all susceptible to earthflows. These flows are usually controlled by the pore water pressures within the mass, which should be high enough to produce

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2640-518: A wide range of ground movements, such as rockfalls , mudflows , shallow or deep-seated slope failures and debris flows . Landslides occur in a variety of environments, characterized by either steep or gentle slope gradients, from mountain ranges to coastal cliffs or even underwater, in which case they are called submarine landslides . Gravity is the primary driving force for a landslide to occur, but there are other factors affecting slope stability that produce specific conditions that make

2760-452: Is a measure of the work (more precisely, the torque ) that results in inelastic (permanent) displacement or distortion of the Earth's crust. It is related to the total energy released by an earthquake. However, the power or potential destructiveness of an earthquake depends (among other factors) on how much of the total energy is converted into seismic waves. This is typically 10% or less of

2880-408: Is among the victims; they get back together, and Tousei allows them to. In Makiko Hirata's josei manga and anime Kasei Yakyoku the story finishes some time after the earthquake, as a corollary to the main love triangle between the noblewoman Akiko Hashou, her lover Taka Itou, and Akiko's personal maid Sara Uchida. The earthquake happens just as the marriage between Akiko and her fiancé Kiyosu Saionji

3000-719: Is an appropriate tool because it has functions of collection, storage, manipulation, display, and analysis of large amounts of spatially referenced data which can be handled fast and effectively. Cardenas reported evidence on the exhaustive use of GIS in conjunction of uncertainty modelling tools for landslide mapping. Remote sensing techniques are also highly employed for landslide hazard assessment and analysis. Before and after aerial photographs and satellite imagery are used to gather landslide characteristics, like distribution and classification, and factors like slope, lithology , and land use/land cover to be used to help predict future events. Before and after imagery also helps to reveal how

3120-565: Is announced. Sara is in the streets, and Taka is taking Sara's brother Junichirou to a hospital after he was injured in a yakuza-related incident. The Hashou's mansion is destroyed, leading to an emotional confrontation between Akiko and Saionji; meanwhile, Sara's humble house in the suburbia is also destroyed and her and Junichirou's mother dies of injuries she sustained in the earthquake. Maurice Tourneur 's 1924 silent film Torment has an earthquake in Yokohama in its plot, and uses footage of

3240-429: Is approximately related to seismic moment by where η R = E s / ( E s + E f ) {\displaystyle \eta _{R}=E_{s}/(E_{s}+E_{f})} is radiated efficiency and Δ σ s {\displaystyle \Delta \sigma _{s}} is the static stress drop, i.e., the difference between shear stresses on

3360-505: Is complete and ignores fracture energy), (where E is in Joules and M 0   is in N ⋅ {\displaystyle \cdot } m), Kanamori approximated M w   by The formula above made it much easier to estimate the energy-based magnitude M w  , but it changed the fundamental nature of the scale into a moment magnitude scale. USGS seismologist Thomas C. Hanks noted that Kanamori's M w   scale

3480-475: Is designated as Disaster Prevention Day to commemorate the earthquake and remind people of the importance of preparedness, as August and September are the peak of the typhoon season. Schools and public and private organizations host disaster drills. Tokyo is located near a fault zone beneath the Izu Peninsula which, on average, causes a major earthquake about once every 70 years, and is also located near

3600-434: Is determined by certain geologic factors, and that future landslides will occur under the same conditions as past events. Therefore, it is necessary to establish a relationship between the geomorphologic conditions in which the past events took place and the expected future conditions. Natural disasters are a dramatic example of people living in conflict with the environment. Early predictions and warnings are essential for

3720-514: Is essentially due to a decrease in the shear strength of the slope material, an increase in the shear stress borne by the material, or a combination of the two. A change in the stability of a slope can be caused by a number of factors, acting together or alone. Natural causes of landslides include: Landslides are aggravated by human activities, such as: In traditional usage, the term landslide has at one time or another been used to cover almost all forms of mass movement of rocks and regolith at

1923 Great Kantō earthquake - Misplaced Pages Continue

3840-459: Is estimated to have exceeded US$ 1 billion (or about $ 18 billion today). There were 57 aftershocks. Ethnic Koreans were massacred after the earthquake. The Home Ministry declared martial law and ordered all sectional police chiefs to make maintenance of order and security a top priority. A false rumor was spread that Koreans were taking advantage of the disaster, committing arson and robbery, and were in possession of bombs. Anti-Korean sentiment

3960-457: Is fluid-like and generally much more rapid. This is usually a result of lower shear resistances and steeper slopes. Typically, debris slides start with the detachment of large rock fragments high on the slopes, which break apart as they descend. Clay and silt slides are usually slow but can experience episodic acceleration in response to heavy rainfall or rapid snowmelt. They are often seen on gentle slopes and move over planar surfaces, such as over

4080-471: Is more directly related to the energy of an earthquake than other scales, and does not saturate – that is, it does not underestimate magnitudes as other scales do in certain conditions. It has become the standard scale used by seismological authorities like the U.S. Geological Survey for reporting large earthquakes (typically M > 4), replacing the local magnitude (M L  ) and surface-wave magnitude (M s  ) scales. Subtypes of

4200-426: Is only valid for (≤ 7.0). Seismic moment is not a direct measure of energy changes during an earthquake. The relations between seismic moment and the energies involved in an earthquake depend on parameters that have large uncertainties and that may vary between earthquakes. Potential energy is stored in the crust in the form of elastic energy due to built-up stress and gravitational energy . During an earthquake,

4320-544: Is provided below. Under this classification, six types of movement are recognized. Each type can be seen both in rock and in soil. A fall is a movement of isolated blocks or chunks of soil in free-fall. The term topple refers to blocks coming away by rotation from a vertical face. A slide is the movement of a body of material that generally remains intact while moving over one or several inclined surfaces or thin layers of material (also called shear zones) in which large deformations are concentrated. Slides are also sub-classified by

4440-487: Is taken in by a friend of the late Takao, Dr. Oikawa. Waki Yamato 's manga Haikara-san ga Tōru actually reaches its climax after the Great Kantō earthquake—which happens right before the wedding of the female lead, Benio Hanamura, and her second love Tousei. Benio barely survives when the Christian church she's getting married in collapses, and then she finds her long-lost love Shinobu whose other love interest Larissa

4560-463: Is technically difficult since it involves the integration of wave energy over the entire frequency band. To simplify this calculation, he noted that the lowest frequency parts of the spectrum can often be used to estimate the rest of the spectrum. The lowest frequency asymptote of a seismic spectrum is characterized by the seismic moment , M 0  . Using an approximate relation between radiated energy and seismic moment (which assumes stress drop

4680-620: Is the same for all earthquakes, one can consider M w   as a measure of the energy E s radiated by earthquakes. Under these assumptions, the following formula, obtained by solving for M 0   the equation defining M w  , allows one to assess the ratio E 1 / E 2 {\displaystyle E_{1}/E_{2}} of energy release (potential or radiated) between two earthquakes of different moment magnitudes, m 1 {\displaystyle m_{1}} and m 2 {\displaystyle m_{2}} : As with

4800-420: Is thus poorly known. It could vary highly from one earthquake to another. Two earthquakes with identical M 0 {\displaystyle M_{0}} but different σ ¯ {\displaystyle {\overline {\sigma }}} would have released different Δ W {\displaystyle \Delta W} . The radiated energy caused by an earthquake

4920-404: The 1960 Chilean and 1964 Alaskan earthquakes. These had M s   magnitudes of 8.5 and 8.4 respectively but were notably more powerful than other M 8 earthquakes; their moment magnitudes were closer to 9.6 and 9.3, respectively. The study of earthquakes is challenging as the source events cannot be observed directly, and it took many years to develop the mathematics for understanding what

1923 Great Kantō earthquake - Misplaced Pages Continue

5040-613: The Imperial Hotel, Tokyo , to withstand the quake, although in fact the building was damaged, though standing, by the shock. The destruction of the US embassy caused Ambassador Cyrus Woods to relocate the embassy to the hotel. Wright's structure withstood the anticipated earthquake stresses, and the hotel remained in use until 1968. The innovative design used to construct the Imperial Hotel, and its structural fortitude, inspired

5160-547: The Sagami Trough , a large subduction zone that has potential for large earthquakes. Every year on this date, schools across Japan take a moment of silence at the precise time the earthquake hit in memory of the lives lost. Some discreet memorials are located in Yokoamicho Park in Sumida Ward , at the site of the open space in which an estimated 38,000 people were killed by a single fire whirl . The park houses

5280-437: The local magnitude/Richter scale (M L  ) defined by Charles Francis Richter in 1935, it uses a logarithmic scale ; small earthquakes have approximately the same magnitudes on both scales. Despite the difference, news media often use the term "Richter scale" when referring to the moment magnitude scale. Moment magnitude (M w  ) is considered the authoritative magnitude scale for ranking earthquakes by size. It

5400-510: The 1870s, the rate in Tokyo remained high, more so in the upper-class residential northern and western districts than in the densely populated working-class eastern district. An explanation is the decline of waste disposal, which became particularly serious in the northern and western districts when traditional methods of waste disposal collapsed due to urbanization. The 1923 earthquake led to record-high morbidity due to unsanitary conditions following

5520-621: The 1970s, introducing a separate magnitude associated to radiated energy was warranted. Choy and Boatwright defined in 1995 the energy magnitude where E s {\displaystyle E_{\mathrm {s} }} is in J (N·m). Assuming the values of σ̄/μ are the same for all earthquakes, one can consider M w   as a measure of the potential energy change Δ W caused by earthquakes. Similarly, if one assumes η R Δ σ s / 2 μ {\displaystyle \eta _{R}\Delta \sigma _{s}/2\mu }

5640-414: The Earth's surface. In 1978, geologist David Varnes noted this imprecise usage and proposed a new, much tighter scheme for the classification of mass movements and subsidence processes. This scheme was later modified by Cruden and Varnes in 1996, and refined by Hutchinson (1988), Hungr et al. (2001), and finally by Hungr, Leroueil and Picarelli (2014). The classification resulting from the latest update

5760-580: The Great Kanto earthquake is recreated in the 1998 film, After Life , known in Japanese as Wandafuru Raifu (or Wonderful Life ). Directed by Hirokazu Kore-eda , the plot takes place in a way station for those who have just died. The newly deceased will take their happiest memory with them into the afterlife. One of the newly deceased has a memory of being in the woods after the earthquake. Michiyo Akaishi's josei manga Akatsuki no Aria features

5880-580: The Great Kantō earthquake. In the TV adaptation of the novel Pachinko by Min Jin Lee , a young Hansu escapes Yokohama with his father's former yakuza employer, Ryoichi, from the Great Kantō Earthquake. The Great Kantō Earthquake is not featured in the book. In Oswald Wynd 's novel The Ginger Tree , Mary Mackenzie survives the earthquake, and later bases her clothes designing company in one of

6000-540: The Imperial Army used the pretext of civil unrest to liquidate political dissidents. Socialists such as Hirasawa Keishichi  [ ja ] (平澤計七), anarchists such as Sakae Ōsugi and Noe Itō , and the Chinese communal leader, Ō Kiten  [ ja ] (王希天), were abducted and killed by local police and Imperial Army, who claimed the radicals intended to use the crisis as an opportunity to overthrow

6120-446: The Japanese construction company Kajima Kobori Research's conclusive report of September 2004, 105,385 deaths were confirmed in the 1923 quake. The damage from this natural disaster was one of the greatest sustained by Imperial Japan . In 1960, on the 37th anniversary of the quake, the government declared September 1 an annual "Disaster Prevention Day". Because the earthquake struck when people were cooking meals, many were killed as

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6240-651: The Japanese government. Director Chongkong Oh made two documentary films about the pogrom : Hidden Scars: The Massacre of Koreans from the Arakawa River Bank to Shitamachi in Tokyo (1983) and The Disposed-of Koreans: The Great Kanto Earthquake and Camp Narashino (1986). They largely consist of interviews with survivors, witnesses, and perpetrators. The importance of obtaining and providing accurate information following natural disasters has been emphasized in Japan ever since. Earthquake preparation literature in modern Japan almost always directs citizens to carry

6360-483: The Japanese people for their self-centered, immoral, and extravagant lifestyles. In the long run, the response to the disaster was a strong sense that Japan had been given an unparalleled opportunity to rebuild the city and rebuild Japanese values. In reconstructing the city, the nation, and the Japanese people, the earthquake fostered a culture of catastrophe and reconstruction that amplified discourses of moral degeneracy and national renovation in interwar Japan, fostering

6480-683: The Japanese police and bands of armed vigilantes killed ethnic Korean civilians and anyone they suspected of being Korean. Estimates of the death toll from the massacre vary, with most third-party sources citing fatalities ranging from 6,000 to 10,000. Since 1960, September 1 has been designated by the Japanese government as Disaster Prevention Day ( 防災の日 , Bōsai no hi ) , or a day in remembrance of and to prepare for major natural disasters including tsunami and typhoons . Drills, as well as knowledge promotion events, are centered around that date as well as awards ceremonies for people of merit. The SS Dongola 's captain reported that, while he

6600-474: The Japanese seismologist Kiyoo Wadati showed that the maximum amplitude of an earthquake's seismic waves diminished with distance at a certain rate. Charles F. Richter then worked out how to adjust for epicentral distance (and some other factors) so that the logarithm of the amplitude of the seismograph trace could be used as a measure of "magnitude" that was internally consistent and corresponded roughly with estimates of an earthquake's energy. He established

6720-467: The Kantō earthquake in the film. In the 2013 animated film by director Hayao Miyazaki , The Wind Rises , the protagonist Jiro Horikoshi is traveling to Tokyo by train to study engineering. On the way, the 1923 earthquake strikes, damaging the train and causing a huge fire in the city. In the 2022 animated film Suzume no Tojimari , directed by Makoto Shinkai , the earthquake is briefly alluded to in

6840-457: The Richter scale, an increase of one step on the logarithmic scale of moment magnitude corresponds to a 10 ≈ 32 times increase in the amount of energy released, and an increase of two steps corresponds to a 10 = 1000 times increase in energy. Thus, an earthquake of M w   of 7.0 contains 1000 times as much energy as one of 5.0 and about 32 times that of 6.0. To make the significance of

6960-631: The area of the Val Pola disaster (Italy). Evidence of past landslides has been detected on many bodies in the solar system, but since most observations are made by probes that only observe for a limited time and most bodies in the solar system appear to be geologically inactive not many landslides are known to have happened in recent times. Both Venus and Mars have been subject to long-term mapping by orbiting satellites, and examples of landslides have been observed on both planets. Landslide mitigation refers to several human-made activities on slopes with

7080-593: The coast of Sagami Bay , Bōsō Peninsula , Izu Islands , and the east coast of Izu Peninsula within minutes. The tsunami caused many deaths, including about 100 people along Yui-ga-hama Beach in Kamakura and an estimated 50 people on the Enoshima causeway. Over 570,000 homes were destroyed, leaving an estimated 1.9 million homeless. Evacuees were transported by ship from Kantō to as far as Kobe in Kansai. The damage

7200-518: The corresponding explosion energy, a value of 4.2 x 10 joules per ton of TNT applies. The table illustrates the relationship between seismic energy and moment magnitude. The end of the scale is at the value 10.6, corresponding to the assumption that at this value the Earth's crust would have to break apart completely. Landslide Landslides , also known as landslips , or rockslides , are several forms of mass wasting that may include

7320-615: The creation of the popular Lincoln Logs toy. The unfinished battlecruiser Amagi was in drydock being converted into an aircraft carrier in Yokosuka in compliance with the Washington Naval Treaty of 1922. The earthquake damaged the ship's hull beyond repair, leading it to be scrapped , and the unfinished fast battleship Kaga was converted into an aircraft carrier in its place. In contrast to London , where typhoid fever had been steadily declining since

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7440-579: The development of guidelines for sustainable land-use planning . The analysis is used to identify the factors that are related to landslides, estimate the relative contribution of factors causing slope failures, establish a relation between the factors and landslides, and to predict the landslide hazard in the future based on such a relationship. The factors that have been used for landslide hazard analysis can usually be grouped into geomorphology , geology , land use/land cover, and hydrogeology . Since many factors are considered for landslide hazard mapping, GIS

7560-428: The earthquake (e.g., equation 3 of Venkataraman & Kanamori 2004 ) and μ {\displaystyle \mu } is the average of the shear moduli of the rocks that constitute the fault. Currently, there is no technology to measure absolute stresses at all depths of interest, nor method to estimate it accurately, and σ ¯ {\displaystyle {\overline {\sigma }}}

7680-432: The earthquake in volume 8. Several places frequented by the protagonist Aria Kanbara, like her boarding school and the house of the rich Nishimikado clan that she is an illegitimate member of, become shelters for the wounded and the homeless. Aria's birth mother is severely injured by debris and later dies, and this triggers a subplot about Aria's own heritage. In Yuu Watase's 2017 josei manga Fushigi Yûgi Byakko Senki ,

7800-450: The earthquake struck Tokyo, and were never in any danger. American Acting Consul General Max David Kirjassoff and his wife Alice Josephine Ballantine Kirjassoff died in the earthquake. The consulate itself lost the entirety of its records in the subsequent fires. Many homes were buried or swept away by landslides in the mountainous and hilly coastal areas in western Kanagawa Prefecture ; about 800 people died. A collapsing mountainside in

7920-595: The earthquake were incinerated. The earthquake broke water mains all over the city, and putting out the fires took until late in the morning of September 3, nearly two full days. A strong typhoon centered off the coast of the Noto Peninsula in Ishikawa Prefecture brought high winds to Tokyo Bay at about the same time as the earthquake. These winds caused fires to spread rapidly. Emperor Taishō and Empress Teimei were staying at Nikko when

8040-399: The earthquake's equivalent double-couple. (More precisely, it is the scalar magnitude of the second-order moment tensor that describes the force components of the double-couple. ) Seismic moment is measured in units of Newton meters (N·m) or Joules , or (in the older CGS system) dyne-centimeters (dyn-cm). The first calculation of an earthquake's seismic moment from its seismic waves

8160-544: The earthquake, and it prompted the establishment of antityphoid measures and the building of urban infrastructure. The Honda Point Disaster on the West Coast of the United States, in which seven US Navy destroyers ran aground eight days later, killing 23 sailors, has been attributed in part to navigational errors caused by unusual currents set up by the earthquake in Japan. Beginning in 1960, every September 1

8280-468: The effects of climate change on landslides need to be studied on a regional scale. Climate change can have both positive and negative impacts on landslides Temperature rise may increase evapotranspiration, leading to a reduction in soil moisture and stimulate vegetation growth, also due to a CO2 increase in the atmosphere. Both effects may reduce landslides in some conditions. On the other side, temperature rise causes an increase of landslides due to Since

8400-409: The energy released, and the stress drop (essentially how much of the potential energy was released). In particular, he derived an equation that relates an earthquake's seismic moment to its physical parameters: with μ being the rigidity (or resistance to moving) of a fault with a surface area of S over an average dislocation (distance) of ū . (Modern formulations replace ūS with

8520-406: The environment , can increase the frequency of natural events (such as extreme weather ) which trigger landslides. Landslide mitigation describes the policy and practices for reducing the risk of human impacts of landslides, reducing the risk of natural disaster . Landslides occur when the slope (or a portion of it) undergoes some processes that change its condition from stable to unstable. This

8640-487: The equivalent D̄A , known as the "geometric moment" or "potency". ) By this equation the moment determined from the double couple of the seismic waves can be related to the moment calculated from knowledge of the surface area of fault slippage and the amount of slip. In the case of the Niigata earthquake the dislocation estimated from the seismic moment reasonably approximated the observed dislocation. Seismic moment

8760-460: The fact that they only provided a comparison of the amplitude of waves produced at a standard distance and frequency band; it was difficult to relate these magnitudes to a physical property of the earthquake. Gutenberg and Richter suggested that radiated energy E s could be estimated as (in Joules). Unfortunately, the duration of many very large earthquakes was longer than 20 seconds, the period of

8880-1161: The fault before and after the earthquake (e.g., from equation 1 of Venkataraman & Kanamori 2004 ). These two quantities are far from being constants. For instance, η R {\displaystyle \eta _{R}} depends on rupture speed; it is close to 1 for regular earthquakes but much smaller for slower earthquakes such as tsunami earthquakes and slow earthquakes . Two earthquakes with identical M 0 {\displaystyle M_{0}} but different η R {\displaystyle \eta _{R}} or Δ σ s {\displaystyle \Delta \sigma _{s}} would have radiated different E s {\displaystyle E_{\mathrm {s} }} . Because E s {\displaystyle E_{\mathrm {s} }} and M 0 {\displaystyle M_{0}} are fundamentally independent properties of an earthquake source, and since E s {\displaystyle E_{\mathrm {s} }} can now be computed more directly and robustly than in

9000-452: The few buildings that remained standing in the aftermath. In Natsumi's short story Taishō Romance , about a boy in the Reiwa era who became a pen pal with a Taishō-era girl, the story mentions the Great Kantō earthquake, causing the boy unable to contact her. The short story was adapted to the song " Taishō Roman " by Yoasobi , which the music video shows the giant clock pointing to 11:58,

9120-452: The fluidization of landslide material as it gains speed or incorporates further debris and water along its path. River blockages as the flow reaches a main stream can generate temporary dams. As the impoundments fail, a domino effect may be created, with a remarkable growth in the volume of the flowing mass, and in its destructive power. An earthflow is the downslope movement of mostly fine-grained material. Earthflows can move at speeds within

9240-713: The form of the surface(s) or shear zone(s) on which movement happens. The planes may be broadly parallel to the surface ("planar slides") or spoon-shaped ("rotational slides"). Slides can occur catastrophically, but movement on the surface can also be gradual and progressive. Spreads are a form of subsidence, in which a layer of material cracks, opens up, and expands laterally. Flows are the movement of fluidised material, which can be both dry or rich in water (such as in mud flows). Flows can move imperceptibly for years, or accelerate rapidly and cause disasters. Slope deformations are slow, distributed movements that can affect entire mountain slopes or portions of it. Some landslides are complex in

9360-462: The goal of lessening the effect of landslides. Landslides can be triggered by many, sometimes concomitant causes. In addition to shallow erosion or reduction of shear strength caused by seasonal rainfall , landslides may be triggered by anthropic activities, such as adding excessive weight above the slope, digging at mid-slope or at the foot of the slope. Often, individual phenomena join to generate instability over time, which often does not allow

9480-550: The heroine Suzuno Osugi enters The Universe of the Four Gods for the first time right after the earthquake: her father Takao, who is dying from injuries he suffered when the family house fatally collapsed on him and Suzuno's mother Tamayo, orders her to do so, so she will survive the disaster and its aftermath. After a brief time there, she's sent back to the already destroyed Tokyo, and she, alongside her soon-to-be love interest Seiji Horie and two young boys named Hideo and Kenichi,

9600-447: The interactions of forces) this model is called a couple , also simple couple or single couple . If a second couple of equal and opposite magnitude is applied their torques cancel; this is called a double couple . A double couple can be viewed as "equivalent to a pressure and tension acting simultaneously at right angles". The single couple and double couple models are important in seismology because each can be used to derive how

9720-480: The landscape changed after an event, what may have triggered the landslide, and shows the process of regeneration and recovery. Using satellite imagery in combination with GIS and on-the-ground studies, it is possible to generate maps of likely occurrences of future landslides. Such maps should show the locations of previous events as well as clearly indicate the probable locations of future events. In general, to predict landslides, one must assume that their occurrence

9840-511: The local magnitude and the surface wave magnitude. Thus, a magnitude zero microearthquake has a seismic moment of approximately 1.1 × 10  N⋅m , while the Great Chilean earthquake of 1960, with an estimated moment magnitude of 9.4–9.6, had a seismic moment between 1.4 × 10  N⋅m and 2.8 × 10  N⋅m . Seismic moment magnitude ( M wg or Das Magnitude Scale ) and moment magnitude ( M w ) scales To understand

9960-440: The long runout can be different, but they typically result in the weakening of the sliding mass as the speed increases. The causes of this weakening are not completely understood. Especially for the largest landslides, it may involve the very quick heating of the shear zone due to friction, which may even cause the water that is present to vaporize and build up a large pressure, producing a sort of hovercraft effect. In some cases,

10080-416: The magnitude range 5.0 ≤  M s  ≤ 7.5 is not reliable due to the inconsistency of defined magnitude range (moderate to large earthquakes defined as M s  ≤ 7.0 and M s  = 7–7.5) and scarce data in lower magnitude range (≤ 7.0) which rarely represents the global seismicity (e.g., see Figs. 1A, B, 4 and Table 2 of Percaru and Berckhemer 1978). Furthermore, Equation (1) of Percaru and Berckhemer 1978)

10200-710: The magnitude scales based on M o detailed background of M wg and M w scales is given below. M w scale Hiroo Kanamori defined a magnitude scale (Log W 0  = 1.5 M w  + 11.8, where W 0 is the minimum strain energy) for great earthquakes using Gutenberg Richter Eq. (1). Log Es = 1.5 Ms + 11.8                                                                                     (A) Hiroo Kanamori used W 0 in place of E s (dyn.cm) and consider

10320-427: The magnitude value plausible, the seismic energy released during the earthquake is sometimes compared to the effect of the conventional chemical explosive TNT . The seismic energy E S {\displaystyle E_{\mathrm {S} }} results from the above-mentioned formula according to Gutenberg and Richter to or converted into Hiroshima bombs: For comparison of seismic energy (in joules) with

10440-488: The moment magnitude scale (M ww  , etc.) reflect different ways of estimating the seismic moment. At the beginning of the twentieth century, very little was known about how earthquakes happen, how seismic waves are generated and propagate through the Earth's crust, and what information they carry about the earthquake rupture process; the first magnitude scales were therefore empirical . The initial step in determining earthquake magnitudes empirically came in 1931 when

10560-410: The moment magnitude scale is M w  , with the subscript "w" meaning mechanical work accomplished. The moment magnitude M w   is a dimensionless value defined by Hiroo Kanamori as where M 0   is the seismic moment in dyne ⋅cm (10  N⋅m). The constant values in the equation are chosen to achieve consistency with the magnitude values produced by earlier scales, such as

10680-413: The most important factors that trigger landslides in any given location. Using GIS, extremely detailed maps can be generated to show past events and likely future events which have the potential to save lives, property, and money. Since the ‘90s, GIS have been also successfully used in conjunction to decision support systems , to show on a map real-time risk evaluations based on monitoring data gathered in

10800-431: The movement of a mass over a planar or curvilinear surface or shear zone. A debris slide is a type of slide characterized by the chaotic movement of material mixed with water and/or ice. It is usually triggered by the saturation of thickly vegetated slopes which results in an incoherent mixture of broken timber, smaller vegetation and other debris. Debris flows and avalanches differ from debris slides because their movement

10920-471: The movement of clayey materials, which facilitate the intrusion of water into the moving mass and produce faster responses to precipitation. A rock avalanche, sometimes referred to as sturzstrom , is a large and fast-moving landslide of the flow type. It is rarer than other types of landslides but it is often very destructive. It exhibits typically a long runout, flowing very far over a low-angle, flat, or even slightly uphill terrain. The mechanisms favoring

11040-451: The negative impacts felt by landslides. GIS offers a superior method for landslide analysis because it allows one to capture, store, manipulate, analyze, and display large amounts of data quickly and effectively. Because so many variables are involved, it is important to be able to overlay the many layers of data to develop a full and accurate portrayal of what is taking place on the Earth's surface. Researchers need to know which variables are

11160-581: The ratio of seismic Energy ( E ) and Seismic Moment ( M o ), i.e., E / M o  = 5 × 10 , into the Gutenberg–Richter energy magnitude Eq. (A), Hanks and Kanamori provided Eq. (B): Log M0 = 1.5 Ms + 16.1                                                                                   (B) Note that Eq. (B)

11280-402: The reduction of property damage and loss of life. Because landslides occur frequently and can represent some of the most destructive forces on earth, it is imperative to have a good understanding as to what causes them and how people can either help prevent them from occurring or simply avoid them when they do occur. Sustainable land management and development is also an essential key to reducing

11400-482: The rumor and warning residents against attacking Koreans, but in many cases, vigilante activity only ceased as a result of Army operations against it. In several documented cases, soldiers and policemen participated in the killings, and in other cases, authorities handed groups of Koreans over to local vigilantes, who proceeded to kill them. Amidst the mob violence against Koreans in the Kantō Region, regional police and

11520-478: The rumors as fact, including the allegation that Koreans were poisoning wells. The numerous fires and cloudy well water, a little-known effect of a large quake, all seemed to confirm the rumors of the panic-stricken survivors who were living amidst the rubble. Vigilante groups set up roadblocks in cities, and tested civilians with a shibboleth for supposedly Korean-accented Japanese: deporting, beating, or killing those who failed. Army and police personnel colluded in

11640-401: The same "line of action" but in opposite directions, will cancel; if they cancel (balance) exactly there will be no net translation, though the object will experience stress, either tension or compression. If the pair of forces are offset, acting along parallel but separate lines of action, the object experiences a rotational force, or torque . In mechanics (the branch of physics concerned with

11760-466: The seismic moment calculated from the observed physical dislocation. A double couple model suffices to explain an earthquake's far-field pattern of seismic radiation, but tells us very little about the nature of an earthquake's source mechanism or its physical features. While slippage along a fault was theorized as the cause of earthquakes (other theories included movement of magma, or sudden changes of volume due to phase changes ), observing this at depth

11880-409: The seismic waves from an earthquake can tell about the source event. An early step was to determine how different systems of forces might generate seismic waves equivalent to those observed from earthquakes. The simplest force system is a single force acting on an object. If it has sufficient strength to overcome any resistance it will cause the object to move ("translate"). A pair of forces, acting on

12000-430: The seismic waves generated by an earthquake event should appear in the "far field" (that is, at distance). Once that relation is understood it can be inverted to use the earthquake's observed seismic waves to determine its other characteristics, including fault geometry and seismic moment. In 1923 Hiroshi Nakano showed that certain aspects of seismic waves could be explained in terms of a double couple model. This led to

12120-584: The seismological parameter it is based on, is not measured routinely for smaller quakes. For example, the United States Geological Survey does not use this scale for earthquakes with a magnitude of less than 3.5, which includes the great majority of quakes. Popular press reports most often deal with significant earthquakes larger than M~ 4. For these events, the preferred magnitude is the moment magnitude M w  , not Richter's local magnitude M L  . The symbol for

12240-489: The sense that they feature different movement types in different portions of the moving body, or they evolve from one movement type to another over time. For example, a landslide can initiate as a rock fall or topple and then, as the blocks disintegrate upon the impact, transform into a debris slide or flow. An avalanching effect can also be present, in which the moving mass entrains additional material along its path. Slope material that becomes saturated with water may produce

12360-412: The sliding surface is mostly deeply located, for instance well below the maximum rooting depth of trees. They usually involve deep regolith , weathered rock, and/or bedrock and include large slope failures associated with translational, rotational, or complex movements. They tend to form along a plane of weakness such as a fault or bedding plane . They can be visually identified by concave scarps at

12480-459: The surface waves used in the measurement of M s  . This meant that giant earthquakes such as the 1960 Chilean earthquake (M 9.5) were only assigned an M s  8.2. Caltech seismologist Hiroo Kanamori recognized this deficiency and took the simple but important step of defining a magnitude based on estimates of radiated energy, M w  , where the "w" stood for work (energy): Kanamori recognized that measurement of radiated energy

12600-452: The time that the earthquake occurred. The earthquake is recreated in the 1983 asadora Oshin , from episode 114 to 117, showing the financial and human losses the disaster caused, as the new factory Oshin and her husband Ryuzo built is destroyed, and their faithful retainer Genji dies protecting their son Yu. The earthquake becomes a major a plot point as it drives the family to move to Saga, to live with Ryuzo's parents. An incident after

12720-726: The top and steep areas at the toe. Deep-seated landslides also shape landscapes over geological timescales and produce sediment that strongly alters the course of fluvial streams . Landslides that occur undersea, or have impact into water e.g. significant rockfall or volcanic collapse into the sea, can generate tsunamis . Massive landslides can also generate megatsunamis , which are usually hundreds of meters high. In 1958, one such tsunami occurred in Lituya Bay in Alaska. Landslide hazard analysis and mapping can provide useful information for catastrophic loss reduction, and assist in

12840-445: The total energy, the rest being expended in fracturing rock or overcoming friction (generating heat). Nonetheless, seismic moment is regarded as the fundamental measure of earthquake size, representing more directly than other parameters the physical size of an earthquake. As early as 1975 it was considered "one of the most reliably determined instrumental earthquake source parameters". Most earthquake magnitude scales suffered from

12960-413: The underlying bedrock. Failure surfaces can also form within the clay or silt layer itself, and they usually have concave shapes, resulting in rotational slides Slope failure mechanisms often contain large uncertainties and could be significantly affected by heterogeneity of soil properties. A landslide in which the sliding surface is located within the soil mantle or weathered bedrock (typically to

13080-474: The very high temperature may even cause some of the minerals to melt. During the movement, the rock in the shear zone may also be finely ground, producing a nanometer-size mineral powder that may act as a lubricant, reducing the resistance to motion and promoting larger speeds and longer runouts. The weakening mechanisms in large rock avalanches are similar to those occurring in seismic faults. Slides can occur in any rock or soil material and are characterized by

13200-589: The vigilante killings in some areas. Of the 3,000 Koreans taken into custody at the Army Cavalry Regiment base in Narashino , Chiba Prefecture , 10% were killed at the base, or after being released into nearby villages. Moreover, anyone mistakenly identified as Korean, such as Chinese, Ryukyuans , and Japanese speakers of some regional dialects, suffered the same fate. About 700 Chinese, mostly from Wenzhou , were killed. A monument commemorating this

13320-523: The village of Nebukawa, west of Odawara , pushed the entire village and a passenger train carrying over 100 passengers, along with the railway station, into the sea. The RMS Empress of Australia was about to leave Yokohama harbor when the earthquake struck. It narrowly survived and assisted in rescuing 2,000 survivors. A P&O liner, Dongola , was also in the harbor at the moment of disaster and rescued 505 people, taking them to Kobe . A tsunami with waves up to 10 m (33 ft) high struck

13440-400: Was already derived by Hiroo Kanamori and termed it as M w . Eq. (B) was based on large earthquakes; hence, in order to validate Eq. (B) for intermediate and smaller earthquakes, Hanks and Kanamori (1979) compared this Eq. (B) with Eq. (1) of Percaru and Berckhemer (1978) for the magnitude 5.0 ≤  M s  ≤ 7.5 (Hanks and Kanamori 1979). Note that Eq. (1) of Percaru and Berckhemer (1978) for

13560-407: Was anchored in Yokohama's inner harbor: At 11.55 a.m. ship commenced to tremble and vibrate violently and on looking towards the shore it was seen that a terrible earthquake was taking place, buildings were collapsing in all directions and in a few minutes nothing could be seen for clouds of dust. When these cleared away fire could be seen starting in many directions and in half an hour the whole city

13680-711: Was built in 1993 in Wenzhou. In response, the government called upon the Japanese Army and the police to protect Koreans; 23,715 Koreans were placed in protective custody across Japan, 12,000 in Tokyo alone. The chief of police of Tsurumi (or Kawasaki by some accounts) is reported to have publicly drunk the well water to disprove the rumor that Koreans had been poisoning wells. In some towns, even police stations into which Korean people had escaped were attacked by mobs, whereas in other neighborhoods, civilians took steps to protect them. The Army distributed flyers denying

13800-451: Was by Keiiti Aki for the 1964 Niigata earthquake . He did this two ways. First, he used data from distant stations of the WWSSN to analyze long-period (200 second) seismic waves (wavelength of about 1,000 kilometers) to determine the magnitude of the earthquake's equivalent double couple. Second, he drew upon the work of Burridge and Knopoff on dislocation to determine the amount of slip,

13920-490: Was heightened by fear of the Korean independence movement . In the confusion after the quake, mass murder of Koreans by mobs occurred in urban Tokyo and Yokohama, fueled by rumors of rebellion and sabotage. The government reported that 231 Koreans were killed by mobs in Tokyo and Yokohama in the first week of September. Independent reports said the number of dead was far higher, ranging from 6,000 to 10,000. Some newspapers reported

14040-596: Was in flames. This earthquake devastated Tokyo , the port city of Yokohama , and the surrounding prefectures of Chiba , Kanagawa , and Shizuoka , and caused widespread damage throughout the Kantō region. The earthquake's force was so great that in Kamakura , over 60 km (37 mi) from the epicenter, it moved the Great Buddha statue, which weighs about 121 tonnes, almost 60 centimeters. Estimated casualties totaled about 142,800 deaths, including about 40,000 who went missing and were presumed dead. According to

14160-580: Was not possible, and understanding what could be learned about the source mechanism from the seismic waves requires an understanding of the source mechanism. Modeling the physical process by which an earthquake generates seismic waves required much theoretical development of dislocation theory , first formulated by the Italian Vito Volterra in 1907, with further developments by E. H. Love in 1927. More generally applied to problems of stress in materials, an extension by F. Nabarro in 1951

14280-593: Was recognized by the Russian geophysicist A. V. Vvedenskaya as applicable to earthquake faulting. In a series of papers starting in 1956 she and other colleagues used dislocation theory to determine part of an earthquake's focal mechanism, and to show that a dislocation – a rupture accompanied by slipping – was indeed equivalent to a double couple. In a pair of papers in 1958, J. A. Steketee worked out how to relate dislocation theory to geophysical features. Numerous other researchers worked out other details, culminating in

14400-521: Was very similar to a relationship between M L   and M 0   that was reported by Thatcher & Hanks (1973) Hanks & Kanamori (1979) combined their work to define a new magnitude scale based on estimates of seismic moment where M 0 {\displaystyle M_{0}} is defined in newton meters (N·m). Moment magnitude is now the most common measure of earthquake size for medium to large earthquake magnitudes, but in practice, seismic moment (M 0  ),

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