Richter magnitude scale
The so-called Richter magnitude scale – more Richter's magnitude scale, or just Richter magnitude – for measuring the strength of earthquakes refers to the original "magnitude scale" developed by Charles F. Richter and presented in his landmark 1935 paper, revised and renamed the Local magnitude scale, denoted as "ML" or "ML"; because of various shortcomings of the ML scale most seismological authorities now use other scales, such as the moment magnitude scale, to report earthquake magnitudes, but much of the news media still refers to these as "Richter" magnitudes. All magnitude scales retain the logarithmic character of the original, are scaled to have comparable numeric values. Prior to the development of the magnitude scale the only measure of an earthquake's strength or "size" was a subjective assessment of the intensity of shaking observed near the epicenter of the earthquake, categorized by various seismic intensity scales such as the Rossi-Forel scale. In 1883 John Milne surmised that the shaking of large earthquakes might generate waves detectable around the globe, in 1899 E. Von Rehbur Paschvitz observed in Germany seismic waves attributable to an earthquake in Tokyo.
In the 1920s Harry O. Wood and John A. Anderson developed the Wood–Anderson seismograph, one of the first practical instruments for recording seismic waves. Wood built, under the auspices of the California Institute of Technology and the Carnegie Institute, a network of seismographs stretching across Southern California, he recruited the young and unknown Charles Richter to measure the seismograms and locate the earthquakes generating the seismic waves. In 1931 Kiyoo Wadati showed how he had measured, for several strong earthquakes in Japan, the amplitude of the shaking observed at various distances from the epicenter, he plotted the logarithm of the amplitude against the distance, found a series of curves that showed a rough correlation with the estimated magnitudes of the earthquakes. Richter resolved some difficulties with this method using data collected by his colleague Beno Gutenberg, produced similar curves, confirming that they could be used to compare the relative magnitudes of different earthquakes.
To produce a practical method of assigning an absolute measure of magnitude required additional developments. First, to span the wide range of possible values Richter adopted Gutenberg's suggestion of a logarithmic scale, where each step represents a tenfold increase of magnitude, similar to the magnitude scale used by astronomers for star brightness. Second, he wanted a magnitude of zero to be around the limit of human perceptibility. Third, he specified the Wood–Anderson seismograph as the standard instrument for producing seismograms. Magnitude was defined as "the logarithm of the maximum trace amplitude, expressed in microns", measured at a distance of 100 km; the scale was calibrated by defining a magnitude 3 shock as one that produces a maximum amplitude of 1 micron on a seismogram recorded by a Wood–Anderson torsion seismograph. Richter calculated a table of distance corrections, in that for distances less than 200 kilometers the attenuation is affected by the structure and properties of the regional geology.
When Richter presented the resulting scale in 1935 he called it a "magnitude" scale. "Richter magnitude" appears to have originated when Perry Byerly told the press that the scale was Richter's, "should be referred to as such." In 1956 Gutenberg and Richter, while still referring to "magnitude scale", labelled it "local magnitude", with the symbol ML , to distinguish it from two other scales they had developed, the surface wave magnitude and body wave magnitude scales. The Richter scale was defined in 1935 for particular instruments; the particular instrument used would become saturated by strong earthquakes and unable to record high values. The scale was replaced in the 1970s by the moment magnitude scale. Although values measured for earthquakes now are M w, they are reported by the press as Richter values for earthquakes of magnitude over 8, when the Richter scale becomes meaningless. Anything above 5 is classified as a risk by the USGS; the Richter and MMS scales measure the energy released by an earthquake.
The energy and effects are not strongly correlated. Several scales have been described as the "Richter scale" the local magnitude M L and the surface wave M s scale. In addition, the body wave magnitude, m b, the moment magnitude, M w, abbreviated MMS, have been used for decades. A couple of new techniques to measure magnitude are in the development stage by seismologists. All magnitude scales have been designed to give numerically similar results; this goal has been achieved well for M
A seismometer is an instrument that responds to ground motions, such as caused by earthquakes, volcanic eruptions, explosions. Seismometers are combined with a timing device and a recording device to form a seismograph; the output of such a device — recorded on paper or film, now recorded and processed digitally — is a seismogram. Such data is used to locate and characterize earthquakes, to study the earth's internal structure. A simple seismometer, sensitive to up-down motions of the Earth, is like a weight hanging from a spring, both suspended from a frame that moves along with any motion detected; the relative motion between the weight and the frame provides a measurement of the vertical ground motion. A rotating drum is attached to the frame and a pen is attached to the weight, thus recording any ground motion in a seismogram. Any movement of the ground moves the frame; the mass tends not to move because of its inertia, by measuring the movement between the frame and the mass, the motion of the ground can be determined.
Early seismometers used optical levers or mechanical linkages to amplify the small motions involved, recording on soot-covered paper or photographic paper. Modern instruments use electronics. In some systems, the mass is held nearly motionless relative to the frame by an electronic negative feedback loop; the motion of the mass relative to the frame is measured, the feedback loop applies a magnetic or electrostatic force to keep the mass nearly motionless. The voltage needed to produce this force is the output of the seismometer, recorded digitally. In other systems the weight is allowed to move, its motion produces an electrical charge in a coil attached to the mass which voltage moves through the magnetic field of a magnet attached to the frame; this design is used in a geophone, used in exploration for oil and gas. Seismic observatories have instruments measuring three axes: north-south, east-west, vertical. If only one axis is measured, it is the vertical because it is less noisy and gives better records of some seismic waves.
The foundation of a seismic station is critical. A professional station is sometimes mounted on bedrock; the best mountings may be in deep boreholes, which avoid thermal effects, ground noise and tilting from weather and tides. Other instruments are mounted in insulated enclosures on small buried piers of unreinforced concrete. Reinforcing rods and aggregates would distort the pier as the temperature changes. A site is always surveyed for ground noise with a temporary installation before pouring the pier and laying conduit. European seismographs were placed in a particular area after a destructive earthquake. Today, they are concentrated in high-risk regions; the word derives from the Greek σεισμός, seismós, a shaking or quake, from the verb σείω, seíō, to shake. Seismograph is another Greek term from γράφω, gráphō, to draw, it is used to mean seismometer, though it is more applicable to the older instruments in which the measuring and recording of ground motion were combined, than to modern systems, in which these functions are separated.
Both types provide a continuous record of ground motion. The technical discipline concerning such devices is called seismometry, a branch of seismology; the concept of measuring the "shaking" of something means that the word "seismograph" might be used in a more general sense. For example, a monitoring station that tracks changes in electromagnetic noise affecting amateur radio waves presents an rf seismograph, and Helioseismology studies the "quakes" on the Sun. The first seismometer was made in China during the 2nd Century; the first Western description of the device comes from the French physicist and priest Jean de Hautefeuille in 1703. The modern seismometer was developed in the 19th century. In December 2018, a seismometer was deployed on the planet Mars by the InSight lander, the first time a seismometer was placed onto the surface of another planet. In AD 132, Zhang Heng of China's Han dynasty invented the first seismoscope, called Houfeng Didong Yi; the description we have, from the History of the Later Han Dynasty, says that it was a large bronze vessel, about 2 meters in diameter.
When there was an earthquake, one of the dragons' mouths would open and drop its ball into a bronze toad at the base, making a sound and showing the direction of the earthquake. On at least one occasion at the time of a large earthquake in Gansu in AD 143, the seismoscope indicated an earthquake though one was not felt; the available text says that inside the vessel was a central column that could move along eight tracks. The first earthquake recorded by this seismoscope was "somewhere in the east". Days a rider from the east reported this earthquake. By the 13th century, seismographic devices existed in the Maragheh observatory in Persia. French physicist and priest Jean de Hautefeuille built one in 1703. After 1880, most seismometers were descend
A settler is a person who has migrated to an area and established a permanent residence there to colonize the area. Settlers are from a sedentary culture, as opposed to nomads who share and rotate their settlements with little or no concept of individual land ownership. Settlements are built on land claimed or owned by another group. Many times settlers are backed by large countries, they sometimes leave in search of religious freedom. One can witness how settlers often occupied land residents to long-established peoples, designated as indigenous. In some cases, as colonialist mentalities and laws change, the legal ownership of some lands is contested by indigenous people, who either claim or seek restoration of traditional usage, land rights, native title and related forms of legal ownership or partial control; the word "settler" was not usually used in relation to a variety of peoples who became a part of settler societies, such as enslaved Africans, indentured labourers, or convicts. In the figurative usage, a "person who goes first or does something first" applies to the American English use of "pioneer" to refer to a settler—a person who has migrated to a less occupied area and established permanent residence there to colonize the area.
In United States history it refers to those people. In Canada, the Indian Act, passed in 1876, created a fundamental division between First Nations peoples and all others, who are termed Settlers; as the Indian Act is still in force, this distinction continues to present day with an existing Indigenous-Settler division, set in a settler-colonial context where it reproduces an inequitable racial structure. In this usage, pioneers are among the first to an area, whereas settlers can arrive after first settlement and join others in the process of human settlement; this correlates with the work of military pioneers who were tasked with construction of camps before the main body of troops would arrive at the designated campsite. In Imperial Russia, the government invited Russians or foreign nationals to settle in sparsely populated lands; these settlers were called "colonists". See, e.g. articles Slavo-Serbia, Volga German, Russians in Kazakhstan. Although they are thought of as traveling by sea—the dominant form of travel in the early modern era—significant waves of settlement could use long overland routes, such as the Great Trek by the Boer-Afrikaners in South Africa, or the Oregon Trail in the United States.
Anthropologists record tribal displacement of native settlers who drive another tribe from the lands it held, such as the settlement of lands in the area now called Carmel-by-the-Sea, California where Ohlone peoples settled in areas inhabited by the Esselen tribe. In the Middle East, there are a number of references to various squatter and specific policies referred as "settler". Among those: Iraq – the Arabization program of the Ba'ath Party in the late 1970s in North Iraq, which aimed at settling Arab populations instead of Kurds following the Second Iraqi-Kurdish War. Israel – Israelis who moved to areas captured during the Six-Day War in 1967 are termed Israeli settlers. In recent years Israeli settlers have been settling in Palestinian territory such as the Gaza Strip and West Bank. However, this has caused political unrest and many settlers are forcibly removed from their settlements by the Israeli government. Syria – In recent times, Arab settlers have moved in large numbers to ethnic minority areas, such as northeast Syria.
Women and children experience violence in these dangerous areas because of the conflict. Many natives face displacement. During 1948 Palestine war, in which Israel was created, over 750,000 Palestinians were displaced from their homes and not allowed to return. Oftentimes fences or walls are built preventing the natives from traveling back onto the land. Settlements can make it difficult for native people to continue their work. For example, if the settlers take part of the land which the olive trees grow on the natives no longer have access to those olive trees and their livelihood is compromised. Many are met with violence. Settlers in hypothetical societies, such as on other planets feature in science fiction or fantasy fiction and/or video games. Mascot for Texas Woman's University, more there called the "Pioneer." The reasons for the emigration of settlers vary, but they include the following factors and incentives: the desire to start a new and better life in a foreign land, personal financial hardship, cultural, ethnic, or religious persecution, political oppression, government incentive policies aimed at encouraging foreign settlement.
The colony concerned is sometimes controlled by the government of a settler's home country, emigration is sometimes approved by an imperial government
Midwestern United States
The Midwestern United States referred to as the American Midwest, Middle West, or the Midwest, is one of four census regions of the United States Census Bureau. It occupies the northern central part of the United States, it was named the North Central Region by the Census Bureau until 1984. It is located between the Northeastern United States and the Western United States, with Canada to its north and the Southern United States to its south; the Census Bureau's definition consists of 12 states in the north central United States: Illinois, Iowa, Michigan, Missouri, North Dakota, South Dakota, Wisconsin. The region lies on the broad Interior Plain between the states occupying the Appalachian Mountain range and the states occupying the Rocky Mountain range. Major rivers in the region include, from east to west, the Ohio River, the Upper Mississippi River, the Missouri River. A 2012 report from the United States Census put the population of the Midwest at 65,377,684; the Midwest is divided by the Census Bureau into two divisions.
The East North Central Division includes Illinois, Michigan and Wisconsin, all of which are part of the Great Lakes region. The West North Central Division includes Iowa, Minnesota, North Dakota and South Dakota, several of which are located, at least within the Great Plains region. Chicago is the most populous city in the American Midwest and the third most populous in the entire country. Other large Midwestern cities include: Columbus, Detroit, Kansas City, Minneapolis, Cleveland, St. Louis, St. Paul, Cincinnati and Des Moines. Chicago and its suburbs form the largest metropolitan statistical area with 9.9 million people, followed by Metro Detroit, Minneapolis–St. Paul, Greater St. Louis, Greater Cleveland, Greater Cincinnati, the Kansas City metro area, the Columbus metro area; the term Midwestern has been in use since the 1880s to refer to portions of the central United States. A variant term, Middle West, has been used since the 19th century and remains common. Another term sometimes applied to the same general region is the heartland.
Other designations for the region have fallen out of use, such as the Northwest or Old Northwest and Mid-America. The Northwest Territory was one of the earliest territories of the United States, stretching northwest from the Ohio River to northern Minnesota and the upper-Mississippi; the upper-Mississippi watershed including the Missouri and Illinois Rivers was the setting for the earlier French settlements of the Illinois Country and the Ohio Country. Economically the region is balanced between heavy industry and agriculture, with finance and services such as medicine and education becoming important, its central location makes it a transportation crossroads for river boats, autos and airplanes. Politically, the region swings back and forth between the parties, thus is contested and decisive in elections. After the sociological study Middletown, based on Muncie, commentators used Midwestern cities as "typical" of the nation. Earlier, the rhetorical question, "Will it play in Peoria?", had become a stock phrase using Peoria, Illinois to signal whether something would appeal to mainstream America.
The region has a higher employment-to-population ratio than the Northeast, the West, the South, or the Sun Belt states as of 2011. Traditional definitions of the Midwest include the Northwest Ordinance Old Northwest states and many states that were part of the Louisiana Purchase; the states of the Old Northwest are known as Great Lakes states and are east-north central in the United States. The Ohio River runs along the southeastern section while the Mississippi River runs north to south near the center. Many of the Louisiana Purchase states in the west-north central United States, are known as Great Plains states, where the Missouri River is a major waterway joining with the Mississippi; the Midwest lies north of the 36°30′ parallel that the 1820 Missouri Compromise established as the dividing line between future slave and non-slave states. The Midwest Region is defined by the U. S. Census Bureau as these 12 states: Illinois: Old Northwest, Mississippi River, Ohio River, Great Lakes state Indiana: Old Northwest, Ohio River, Great Lakes state Iowa: Louisiana Purchase, Mississippi River, Missouri River state Kansas: Louisiana Purchase, Great Plains, Missouri River state Michigan: Old Northwest and Great Lakes state Minnesota: Old Northwest, Louisiana Purchase, Mississippi River, part of Red River Colony before 1818, Great Lakes state Missouri: Louisiana Purchase, Mississippi River, Missouri River, border state Nebraska: Louisiana Purchase, Great Plains, Missouri River state North Dakota: Louisiana Purchase, part of Red River Colony before 1818, Great Plains, Missouri River state Ohio: Old Northwest, Ohio River, Great Lakes state.
The southeastern part of the state is part of northern Appalachia South Dakota: Louisiana Purchase, Great Plains, Missouri River state Wisconsin: Old Northwest, Mississippi River, Great Lakes stateVarious organizations define the Midwest with different groups of states. For example, the Council of State Governments, an organization for communication and coordination among state governments, includes in its Midwe
Spanish missions in California
The Spanish missions in California comprise a series of 21 religious outposts or missions established between 1769 and 1833 in today's U. S. State of California. Founded by Catholic priests of the Franciscan order to evangelize the Native Americans, the missions led to the creation of the New Spain province of Alta California and were part of the expansion of the Spanish Empire into the most northern and western parts of Spanish North America. Following long-term secular and religious policy of Spain in Spanish America, the missionaries forced the native Californians to live in settlements called reductions, disrupting their traditional way of life; the missionaries introduced European fruits, cattle, horses and technology. The missions have been accused by critics and now, of various abuses and oppression. In the end, the missions had mixed results in their objectives: to convert and transform the natives into Spanish colonial citizens. By 1810, Spain's king had been imprisoned by the French, financing for military payroll and missions in California ceased.
In 1821, Mexico achieved independence from Spain, although Mexico did not send a governor to California until 1824, only a portion of payroll was reinstated. The 21,000 Mission Indians produced hide and tallow and wool and textiles at this time, the leather products were exported to Boston, South America, Asia which sustained the colonial economy from 1810 until 1830, but tended to give British or New England merchant captains importance; the missions began to lose control over land in the 1820s, as unpaid military men unofficially encroached, but missions maintained authority over native neophytes and control of land holdings until the 1830s. At the peak of its development in 1832, the coastal mission system controlled an area equal to one-sixth of Alta California; the Alta California government secularized the missions after the passage of the Mexican secularization act of 1833. This divided the mission lands into land grants, in effect legitimizing and completing the transfer of Indian congregation lands to military commanders and their most loyal men.
The surviving mission buildings are the state's oldest structures and its most-visited historic monuments. They have become a symbol of California, appearing in many movies and television shows, are an inspiration for Mission Revival architecture; the oldest cities of California formed around or near Spanish missions, including the four largest: Los Angeles, San Diego, San Jose, San Francisco. Prior to 1754, grants of mission lands were made directly by the Spanish Crown. But, given the remote locations and the inherent difficulties in communicating with the territorial governments, power was transferred to the viceroys of New Spain to grant lands and establish missions in North America. Plans for the Alta California missions were laid out under the reign of King Charles III, came at least in part as a response to recent sightings of Russian fur traders along the California coast in the mid 1700s; the missions were to be interconnected by an overland route which became known as the Camino Real.
The detailed planning and direction of the missions was to be carried out by Friar Junípero Serra, O. F. M.. The Rev. Fermín Francisco de Lasuén took up Serra's work and established nine more mission sites, from 1786 through 1798. Work on the coastal mission chain was concluded in 1823, completed after Serra's death in 1784. Plans to build a twenty-second mission in Santa Rosa in 1827 were canceled; the Rev. Pedro Estévan Tápis proposed establishing a mission on one of the Channel Islands in the Pacific Ocean off San Pedro Harbor in 1784, with either Santa Catalina or Santa Cruz being the most locations, the reasoning being that an offshore mission might have attracted potential people to convert who were not living on the mainland, could have been an effective measure to restrict smuggling operations. Governor José Joaquín de Arrillaga approved the plan the following year, however an outbreak of sarampion killing some 200 Tongva people coupled with a scarcity of land for agriculture and potable water left the success of such a venture in doubt, so no effort to found an island mission was made.
In September 1821,the Rev. Mariano Payeras, "Comisario Prefecto" of the California missions, visited Cañada de Santa Ysabel east of Mission San Diego de Alcalá as part of a plan to establish an entire chain of inland missions; the Santa Ysabel Asistencia had been founded in 1818 as a "mother" mission, the plan's expanding beyond never came to fruition. In addition to the presidio and pueblo, the misión was one of the three major agencies employed by the Spanish sovereign to extend its borders and consolidate its colonial territories. Asistencias were small-scale missions that conducted Mass on days of obligation but lacked a resident priest; the Spanish Californians had never strayed from the coast. Each frontier station was forced to be self-supporting, as existing means of supply were inadequate to maintain a
Real estate development
Real estate development, or property development, is a business process, encompassing activities that range from the renovation and re-lease of existing buildings to the purchase of raw land and the sale of developed land or parcels to others. Real estate developers are the people and companies who coordinate all of these activities, converting ideas from paper to real property. Real estate development is different from construction, although many developers manage the construction process. Developers buy land, finance real estate deals, build or have builders build projects, imagine and orchestrate the process of development from the beginning to end. Developers take the greatest risk in the creation or renovation of real estate—and receive the greatest rewards. Developers purchase a tract of land, determine the marketing of the property, develop the building program and design, obtain the necessary public approval and financing, build the structures, rent out and sell it. Sometimes property developers will only undertake part of the process.
For example, some developers source a property and get the plans and permits approved before selling the property with the plans and permits to a builder at a premium price. Alternatively, a developer, a builder may purchase a property with the plans and permits in place so that they do not have the risk of failing to obtain planning approval and can start construction on the development immediately. Developers work with many different counterparts along each step of this process, including architects, city planners, surveyors, contractors, leasing agents, etc. In the Town and Country Planning context in the United Kingdom,'development' is defined in the Town and Country Planning Act 1990 s55. Many aspects of the real estate development process require local or state licensing, such as acting as a real estate broker or sales agent along. A real estate developer is not a professional designation, there are no schools or associations who recognize or protect the term as a trademark. No single path automatically leads to success in real estate development.
Developers come from a variety of disciplines— construction, urban planning, architecture and accounting, among others. Recent specialized programs that award a Master of Real Estate Development degree are available; the graduate programs in real estate development are the most comprehensive education in the real estate industry. Other formal education includes a Master of Science in Real Estate, or an MBA. A development team can be put together in one of several ways. At one extreme, a large company might include many services, from architecture to engineering. At the other end of the spectrum, a development company might consist of one principal and a few staff who hire or contract with other companies and professionals for each service as needed. Assembling a team of professionals to address the environmental, private and political issues inherent in a complex development project is critical. A developer's success depends on the ability to coordinate and lead the completion of a series of interrelated activities efficiently and at the appropriate time.
Development process requires skills of many professionals: architects, landscape architects, civil engineers and site planners to address project design. The general contractor of the project hires subcontractors to put the architectural plans into action. Purchasing unused land for a potential development is sometimes called speculative development. Subdivision of land is the principal mechanism. Technically, subdivision describes the legal and physical steps a developer must take to convert raw land into developed land. Subdivision is a vital part of a community's growth, determining its appearance, the mix of its land uses, its infrastructure, including roads, drainage systems, water and public utilities. Land development can pose the most risk, but can be the most profitable technique as it is dependent on the public sector for approvals and infrastructure and because it involves a long investment period with no positive cash flow. After subdivision is complete, the developer markets the land to a home builder or other end user, for such uses as a warehouse or shopping center.
In any case, use of spatial intelligence tools mitigate the risk of these developers by modeling the population trends and demographic make-up of the sort of customers a home builder or retailer would like to have surrounding their new development. Real estate developments portal Construction Home construction Land consumption Land use Property investment calculator Urban sprawl
San Diego is a city in the U. S. state of California. It is in San Diego County, on the coast of the Pacific Ocean in Southern California 120 miles south of Los Angeles and adjacent to the border with Mexico. With an estimated population of 1,419,516 as of July 1, 2017, San Diego is the eighth-largest city in the United States and second-largest in California, it is part of the San Diego–Tijuana conurbation, the second-largest transborder agglomeration between the U. S. and a bordering country after Detroit–Windsor, with a population of 4,922,723 people. The city is known for its mild year-round climate, natural deep-water harbor, extensive beaches, long association with the United States Navy, recent emergence as a healthcare and biotechnology development center. San Diego has been called "the birthplace of California". Home to the Kumeyaay people, it was the first site visited by Europeans on what is now the West Coast of the United States. Upon landing in San Diego Bay in 1542, Juan Rodríguez Cabrillo claimed the area for Spain, forming the basis for the settlement of Alta California 200 years later.
The Presidio and Mission San Diego de Alcalá, founded in 1769, formed the first European settlement in what is now California. In 1821, San Diego became part of the newly independent Mexico, which reformed as the First Mexican Republic two years later. California became part of the United States in 1848 following the Mexican–American War and was admitted to the union as a state in 1850; the city is the seat of San Diego County and is the economic center of the region as well as the San Diego–Tijuana metropolitan area. San Diego's main economic engines are military and defense-related activities, international trade, manufacturing; the presence of the University of California, San Diego, with the affiliated UCSD Medical Center, has helped make the area a center of research in biotechnology. The original inhabitants of the region are now known as the San La Jolla people; the area of San Diego has been inhabited by the Kumeyaay people. The first European to visit the region was explorer Juan Rodríguez Cabrillo, sailing under the flag of Castile but born in Portugal.
Sailing his flagship San Salvador from Navidad, New Spain, Cabrillo claimed the bay for the Spanish Empire in 1542, named the site "San Miguel". In November 1602, Sebastián Vizcaíno was sent to map the California coast. Arriving on his flagship San Diego, Vizcaíno surveyed the harbor and what are now Mission Bay and Point Loma and named the area for the Catholic Saint Didacus, a Spaniard more known as San Diego de Alcalá. On November 12, 1602, the first Christian religious service of record in Alta California was conducted by Friar Antonio de la Ascensión, a member of Vizcaíno's expedition, to celebrate the feast day of San Diego. Permanent colonization of California and of San Diego began in 1769 with the arrival of four contingents of Spaniards from New Spain and the Baja California peninsula. Two seaborne parties reached San Diego Bay: the San Carlos, under Vicente Vila and including as notable members the engineer and cartographer Miguel Costansó and the soldier and future governor Pedro Fages, the San Antonio, under Juan Pérez.
An initial overland expedition to San Diego from the south was led by the soldier Fernando Rivera and included the Franciscan missionary and chronicler Juan Crespí, followed by a second party led by the designated governor Gaspar de Portolà and including the mission president Junípero Serra. In May 1769, Portolà established the Fort Presidio of San Diego on a hill near the San Diego River, it was the first settlement by Europeans in. In July of the same year, Mission San Diego de Alcalá was founded by Franciscan friars under Serra. By 1797, the mission boasted the largest native population in Alta California, with over 1,400 neophytes living in and around the mission proper. Mission San Diego was the southern anchor in Alta California of the historic mission trail El Camino Real. Both the Presidio and the Mission are National Historic Landmarks. In 1821, Mexico won its independence from Spain, San Diego became part of the Mexican territory of Alta California. In 1822, Mexico began its attempt to extend its authority over the coastal territory of Alta California.
The fort on Presidio Hill was abandoned, while the town of San Diego grew up on the level land below Presidio Hill. The Mission was secularized by the Mexican government in 1834, most of the Mission lands were granted to former soldiers; the 432 residents of the town petitioned the governor to form a pueblo, Juan María Osuna was elected the first alcalde, defeating Pío Pico in the vote. However, San Diego had been losing population throughout the 1830s and in 1838 the town lost its pueblo status because its size dropped to an estimated 100 to 150 residents. Beyond town Mexican land grants expanded the number of California ranchos that modestly added to the local economy. Americans gained increased awareness of California, its commercial possibilities, from the writings of two countrymen involved in the officially forbidden, to foreigners, but economically significant hide and tallow trade, where San Diego was a major port and the only one with an adequate harbor: William Shaler's "Journal of a Voyage Between China and the North-Western Coast of America, Made in 1804" and Richard Henry Dana's more substantial and convincing account, of his 1834–36 voyage, the classic Two Years Before the Mast.
In 1846, the United States went to war against Mexico and sent a naval and land expedition to conquer Alta California. At firs