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74-530: Paganica is a hillside town in the province of L'Aquila , in the Abruzzo region of southern Italy. located at 669 meters above sea level, at the foot of the Gran Sasso d'Italia , about 7 kilometers east of the historic center, along the state road 17 bis that from Bazzano climbs to Campo Imperatore passing for Tempèra, Camarda, Assergi and Fonte Cerreto, with a population of about 10 000 inhabitants, making it

148-461: 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 a reference point and the ten-fold (exponential) scaling of each degree of magnitude, and in 1935 published what he called

222-504: 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

296-500: 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

370-418: 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

444-402: 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

518-463: A result of the 2009 L'Aquila earthquake . The earthquake's epicenter was along the road between L'Aquila and Paganica, Paganica being the closest town to the epicenter. Corsa del cappello The Corsa del cappello (Hat Race) is a relay race in which the baton to be exchanged is a hat. A similar competition took place in past centuries during the Feast of Sant'Antonio Abate (January 17). Many years ago

592-432: 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 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

666-449: 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

740-439: 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

814-616: A valuable organ placed in the church in 1955. The original Sanctuary of the Madonna di Pietraquaria was destroyed by Charles I of Anjou after the battle of Tagliacozzo in 1268 and rebuilt a few centuries later. In 1915, it did not suffer serious damage and was home to many survivors of the quake. There are 108 comuni ( sg. : comune ) in the province [1] . The largest are: Moment magnitude scale The moment magnitude scale ( MMS ; denoted explicitly with M or M w   or Mwg , and generally implied with use of

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888-687: Is Rocca Calascio (used in the 1980s as the location for the movie Ladyhawke ), which is the highest castle in Italy and one of the highest in Europe. Also nearby are several ski resorts like Gran Sasso d'Italia , the highest of the Apennines where in its valley the movie The Name of the Rose was filmed in the end of the 1980s. Sulmona has various piazzas, churches and palaces of historical and touristic interest. Some of these include: The remains of

962-452: 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

1036-429: 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

1110-485: Is challenging as the source events cannot be observed directly, and it took many years to develop the mathematics for understanding what 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

1184-505: 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

1258-426: 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,

1332-463: 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

1406-555: Is the Fontana Luminosa ("Luminous Fountain"), a sculpture of two women bearing large jars, built in the 1930s. The local cemetery includes the grave of Karl Heinrich Ulrichs , a 19th‑century German gay rights pioneer who lived in L'Aquila; every year, gay people from all over the world meet at the cemetery to honour his memory. The surrounding area boasts Roman ruins (the important Roman city of Amiternum ), ancient monasteries, and numerous castles. The best-known of these

1480-620: 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

1554-420: 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

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1628-499: The Richter Scale . While the town of Calascio, which lies below the fortress, was rebuilt, the fortress was not. Avezzano , having been completely destroyed by the earthquake of 1915 , has no monuments of particular interest as do other locations in the region of Abruzzo. However, you can see some important remains of its ancient history. The remains of the ancient Roman site of Alba Fucens are located 7 kilometers north of

1702-494: 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 a distance of approximately 100 to 600 km (62 to 373 mi), conditions where

1776-621: 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 }

1850-497: The 20th century, there were serious population declines in the rural areas, with the near collapse of the province's pastoral agricultural economy, as people moved to cities for work. Since the founding of the Gran Sasso e Monti della Laga and Majella national parks, and the Sirente-Velino Regional Park, tourists have been attracted to the mountainous landscapes. Tourism and associated services have boosted

1924-457: 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

1998-421: The ancient city are of little interest as ruins, but indicate the existence of a considerable town; among them are the vestiges of an amphitheatre , a theatre, and thermae, all of them located outside the gates of the modern city. About 3 km from the city, at the foot of Monte Morrone , are some ruins of reticulated masonry, traditionally believed to be Ovid's villa. Today, they are more properly identified as

2072-488: The castle is the highest fortress in the Apennines . Built of stone and masonry exclusively for military purposes and intended only to accommodate troops and never as residence for nobles, the fortress overlooks the Plain of Navelli at one of the highest points in the ancient Barony of Carapelle. Construction of the fortress started in the tenth century as a single watchtower. A walled courtyard with four cylindrical towers at

2146-439: The city. The Castello Orsini-Colonna was built in 1490 by Gentile Virginio Orsini , who had it built around a pre-existing medieval tower of the twelfth century; it is square, with round towers at the angles. The castle project was probably led by the engineer Francesco di Giorgio Martini . In the sixteenth century the castle was expanded by the order of Marcantonio Colonna , becoming an elegant residence. Severely damaged by

2220-455: The corners around a taller inner tower was added in the thirteenth century. The lower half of the fortress is built with distinctively larger stones than its upper half. It is believed that this feature was to make its base impenetrable to invaders. The fortress was never tested in battle. However, it was badly damaged in November 1461 by an earthquake with an estimated magnitude of 7 to 8 on

2294-408: The deaths of 308 people, injured about 1,500, and left over 66,000 unhoused. At 01:32 GMT (03:32 CEST) on 6 April, an earthquake of 6.3 magnitude struck central Italy with its epicentre near L'Aquila, at 42°25′22″N 13°23′40″E  /  42.4228°N 13.3945°E  / 42.4228; 13.3945  ( Earthquake 6 April 2009 ) . Tourists in L'Aquila come mostly from Italy. In

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2368-569: 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 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

2442-444: 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 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

2516-428: 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 }}}

2590-411: The earthquake of 1915, it was partially restored after 1990. The Tunnels of Claudius are located south of the city. They were built by the emperor Claudius between 41 and 52 AD by which the emperor made the first attempts at draining the huge Lake Fucino . To create the tunnels and the main gallery, 25,000 slaves were needed. They dug 32 wells and six tunnels. The lake was largely drained, but with

2664-437: The earthquake of 2009 and subsequent aftershocks the transept and possibly more of the cathedral has collapsed. The Basilica of San Bernardino (1472) has a fine Renaissance façade by Nicolò Filotesio (commonly called Cola dell'Amatrice), and contains the monumental tomb of the saint, decorated with beautiful sculptures, and executed by Silvestro Ariscola in 1480. The church of Santa Maria di Collemaggio , just outside

2738-399: 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

2812-447: The economy of rural L'Aquila and begun to reverse its population decline. Earthquakes mark the history of the province, especially its capital city L'Aquila. The city suffered earthquakes in the 14th, 15th, and 16th centuries, followed by the 1703 Apennine earthquakes and most recently on 6 April 2009. This caused extensive damage to the city and areas of the province just outside L'Aquila, particularly along SS 17. It also resulted in

2886-409: 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

2960-487: 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

3034-550: The event was reborn and the contending teams come from the four historic districts of the country. More recently, it was extended to the hamlets of the former municipality of Paganica. For many years the race has been held in mid-July, within numerous events. Paganica has a station on the Terni–Sulmona railway , with trains to L'Aquila and Sulmona . [REDACTED] Media related to Paganica at Wikimedia Commons Province of L%27Aquila The province of L'Aquila includes

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3108-460: 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

3182-467: The fall of the Roman Empire the tunnels were obstructed and the lake returned to its previous levels. Many centuries later, Alessandro Torlonia completed the work by finally draining Lake Fucino, building on the original project of the emperor Claudius and turning the land under the great lake into a fertile plain. In 1977, the tunnels were opened as an archaeological park. The Avezzano Cathedral

3256-1161: 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

3330-722: The highest mountains of the Apennines ( Gran Sasso , Maiella and Velino-Sirente ), their highest peak, Corno Grande , the high plain of Campo Imperatore , and Europe's southernmost glacier, the Calderone . The province's major rivers are the Aterno-Pescara, Sangro, Liri, Salto, and the Turano; its major lakes are Lago Scanno and Lago Barrea. It once included the third largest lake on the Italian peninsula, Lago Fucino , which

3404-527: The highest part of the town is the massive Spanish Fort ( Forte Spagnolo ) , erected by the Spanish viceroy Don Pedro de Toledo in 1534. It is currently home to the National Museum of Abruzzo. L'Aquila Cathedral , dedicated to Saint Maximus of Aveia (San Massimo), was built in the 13th century, but crumbled down during the 1703 earthquake. The most recent façade is from the 19th century, but after

3478-447: 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

3552-415: The largest fraction of the city, as well as of considerable economic importance. It is a frazione of the comune of L'Aquila (which is some 7 km far), and has a population of about 5,000. On April 6, 2009, the center was hit by a disastrous earthquake which caused heavy damage to the town (including a burst water pipe, which caused a landslide ), resulting in an almost total evacuation. In 2011

3626-511: 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

3700-416: 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)

3774-710: 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

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3848-427: 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

3922-410: 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

3996-461: The municipality has a museum, with a collection of Roman inscriptions and some illuminated service books. The Palazzi Dragonetti and Persichetti contain private collections of pictures. Outside the town is the Fontana delle novantanove cannelle , a fountain with ninety-nine jets distributed along three walls, constructed in 1272. The source of the fountain is still unknown. A well-known city landmark

4070-463: The object to move ("translate"). A pair of forces, acting on 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

4144-581: 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)

4218-401: The restoration works began, which have recovered part of the historical heritage, and the influx of the population. An old Roman city, in 1254 its citizens took part in the foundation of L'Aquila by Manfred of Sicily . Until 1927 it was an autonomous municipality merged, with others, into L'Aquila. On April 6, 2009, Paganica was severely damaged, with 70 percent of its buildings destroyed, as

4292-472: The sanctuary of Hercules Curinus . Nearby is the Badia Morronese , a large (c. 119 × 140 m) religious complex located near Pope Celestine V 's hermitage. It was founded by Celestine as a chapel in 1241, and was enlarged and later made into a convent. The Rocca Calascio is a mountaintop fortress or rocca in the municipality of Calascio . At an elevation of 1,512 metres (4,961 ft),

4366-466: 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

4440-430: 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

4514-584: 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

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4588-418: 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 the moment magnitude scale (M ww  , etc.) reflect different ways of estimating the seismic moment. At the beginning of the twentieth century, very little

4662-433: 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, a body-wave magnitude scale ( mB ) by Gutenberg and Richter in 1956, and a number of variants – to overcome

4736-459: 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

4810-445: 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

4884-409: The town, has a very fine Romanesque façade of simple design (1270–1280) in red and white marble, with three finely decorated portals and a rose-window above each. The two side doors are also fine. The interior contains the mausoleum of Pope Celestine V erected in 1517. Many smaller churches in the town have similar façades (S. Giusta, S. Silvestro and others). The town also contains some fine palaces:

4958-400: 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

5032-468: Was built in 1000 and documented in the thirteenth century. After its destruction as a result of the earthquake of 1915, it was rebuilt after 1940 in the new central square of Avezzano. The facade is neo-Renaissance travertine. The three portals are topped with mosaics depicting Christ and the two protectors of Avezzano, the Virgin Mary and St. Bartholomew. The church inside presents three large naves and

5106-451: 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,

5180-494: Was drained in one of the 19th century's largest engineering projects. The lake basin is today a flourishing agricultural area and an important technological district. The province is known for its many castles, fortresses and pristine medieval hill towns. The province's two major cities, L'Aquila and Avezzano , have had rapid economic expansion since the late 20th century, with the growth of transportation manufacturing, telecommunications, and computer industries. Throughout most of

5254-516: 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 the Japanese seismologist Kiyoo Wadati showed that the maximum amplitude of an earthquake's seismic waves diminished with distance at

5328-580: 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

5402-593: 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

5476-521: 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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