<P> On October 11, 1918, an earthquake occurred, with an approximate magnitude of 7.3 on the Richter scale, accompanied by a tsunami reaching 6.1 metres (20 ft) in height . The epicenter was located northwest of Aguadilla in the Mona Passage (between Puerto Rico and the Dominican Republic). This earthquake caused great damage and loss of life at Mayagüez, and lesser damage along the west coast . Tremors continued for several weeks . Approximately 116 casualties were reported resulting from the earthquake and 40 from the tsunami . </P> <P> Some politicians were in favor of Puerto Rico becoming an incorporated state of the U.S., while others wanted Puerto Rico to gain independence from the United States . Amid this debate, a nationalist group emerged that encouraged radical activism for Puerto Rico to become independent from the United States . As a consequence of the Jones Act and the establishment of elections, a new political party, the Partido Nacionalista de Puerto Rico (Puerto Rican Nationalist Party), was founded on September 17, 1922 . This party used advocated massive demonstrations and protests against any political activity that was not going to result in Puerto Rico gaining independence . In 1924, Pedro Albizu Campos joined the party and later became the vice president in 1927 . In 1930, Albizu was elected president . Being the president, he instilled many of his political ideologies into the party which was composed heavily of anticolonial politics and feelings of contempt against the United States . In the 1930s, the Nationalist Party, led by president Pedro Albizu Campos failed to attract sufficient electoral support and withdrew from political participation . Increased conflict arose between their adherents and the authorities . On October 20, 1935 Albizu testified against the dean of the University of Puerto Rico, claiming that he wanted to Americanize the institution . Four days later a student assembly gathered and declared Albizu a persona non grata, forbidding him to speak there . Albizu was later arrested and convicted of conspiring to overthrow the American government . He was arrested for breaking the Smith Act of 1940 which declared that it was against the law for anyone to teach or be part of a group that encouraged the overthrow of the American government . </P> <P> On October 23, 1935, a student assembly was planned to be held at the University of Puerto Rico - Río Piedras campus . Its officials asked Governor Blanton Winship to provide armed police officers for the campus, to forestall possible violence . Colonel Elisha Francis Riggs, the U.S. appointed Police Chief, commanded the forces . A couple of police officers spotted what they believed to be a suspicious - looking automobile and asked the driver Ramón S. Pagán for his license . Pagán was the Secretary of the Nationalist Party at this time . He was accompanied in the car by his friends and other Nationalist Party members Pedro Quiñones and Eduardo Rodríguez . The police officers asked Pagán to slowly drive to the police station on Calle Arzuaga, but a block from the station, the police surrounded the vehicle and fired their guns into the car . Pagán, Quiñones, and Rodríguez were not armed with weapons . José Santiago Barea, another Nationalist, was approaching the car when police began shooting . It resulted in the death of the four nationalists and one bystander . </P> <P> In retaliation for the "Río Piedras massacre" at the University of Rio Piedras, on February 23, 1936, Nationalists Hiram Rosado and Elias Beauchamp killed Colonel E. Francis Riggs in San Juan . They were taken into custody where they were killed by policemen and officers while being held at the San Juan headquarters . Rosado and Beauchamp were declared heroes by the Nationalist Party president, Pedro Albizu - Campos . Shortly after, the San Juan Federal Court had Albizu arrested for his incitement of discontent . After initially being found innocent in a jury with seven Puerto Ricans and two North Americans, the judge ordered a new jury which had ten North Americans and two Puerto Ricans, who found him guilty . On July 31, 1936, Albizu and several other Nationalists such as Juan Antonio Corretjer and Clemente Soto Vélez were convicted of being associated with Riggs' murder . They were sentenced to six to 10 years in a federal prison in the United States . </P>

On november 19th puerto rico celebrates the arrival of whom