February 10 – Lenny Villa, a first-year Ateneo Law student, dies of serious physical injuries after three days of bloody hazing rites by the members of Aquila Legis fraternity.[3]
June 15 – Mount Pinatuboerupts, the peak of series of major explosions on June 12–16, in what will be the second largest terrestrial eruption of the 20th century;[4][8][9] volcano's alert level has been raised to the highest, June 9; Typhoon Yunya further worsens lahar flows and ashfalls causing collapse of roofs on structures that contribute to about 350 of 847 deaths. The eruption costs US$700-million in total damages.[5][6][10][11]
September 16 – The Senate, by a 12–11 vote, rejects the proposed RP-US Treaty of Friendship, Cooperation and Peace, which would have extended American military presence at Subic Bay Naval Base.[5][10] American troops earlier abandoned Clark Air Base after Pinatubo erupted, and completed their withdrawal from Subic in 1992.
As per Executive Order No. 292, chapter 7 section 26, the following are regular holidays and special days, approved on July 25, 1987.[18] Note that in the list, holidays in bold are "regular holidays" and those in italics are "nationwide special days".
November 24–December 3 – Manila is selected again as the host city for the 16th Southeast Asian Games, ten years since the 11th SEA Games held in the same city in 1981. The Philippine team participates in the 16th SEA Games and placed second with 91 gold, 62 silver and 84 bronze medals for a total of 237 medals ahead of Indonesia is in the first place.
^Karganilla, Bernard (August 12, 2008). "National Security and History". Malaya - The National Newspaper. Retrieved August 28, 2024 – via Wayback Machine internet archive.
^ ab"Mount Pinatubo: The June 1991 Eruptions". U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Geophysical Data Center. 55: 7. 1992. Retrieved April 21, 2021.
^"At 25, SM Megamall Ushers New Mall Revolution". SM Investments Corporation. August 16, 2016. Archived from the original on April 21, 2021. Retrieved April 21, 2021. SM Megamall opened its doors to the public some 25 years ago on June 28, 1991 with a total floor plate of 311,898 square meters that stretched for almost a mile and consisted of six levels.
^Reid, Robert H. (June 27, 1995). "Murder Allegations Against Senator's Son Shock Country". AP News. Associated Press. Archived from the original on April 21, 2021. Retrieved April 21, 2021. The latest case began on June 30, 1991, when Estrellita Vizconde, 47, and her daughters Carmelita, 18, and Jennifer, 7, were found stabbed to death in their home in a Manila suburb
^For the details of the case: —"G.R. No. 127262" Chan Robles Virtual Law Library. Jul. 24, 1997. (Covering events before and on 1997) Retrieved Jul. 9, 2022. —"G.R. No. 176389" Lawyerly. Dec. 14, 2010. Retrieved Oct. 8, 2021 —"What went before?"Inquirer.net. June 28, 2011. Retrieved Jul. 7, 2022.
^Parker, Dennis J. (2000). Floods. Vol. 1. Taylor & Francis. p. 400. ISBN9780415227438. Retrieved April 21, 2021.
^Reid, Robert (December 27, 1991). "Philippines Announces Subic Closure". AP News. Associated Press. Archived from the original on April 21, 2021. Retrieved April 21, 2021. Clark Air Base, the other major U.S. installation, was closed last month after it was severely damaged by the eruption of Mount Pinatubo. It was handed back to the Philippines on Nov. 27.