1968 Casiguran earthquake
 | |
| UTC time | 1968-08-01 20:19:22 |
|---|---|
| ISC event | 817557 |
| USGS-ANSS | ComCat |
| Local date | August 2, 1968 |
| Local time | 04:19:22 |
| Magnitude | 7.6 Mw[1] 7.3 Ms[2] |
| Depth | 25 km (16 mi)[1] |
| Epicenter | 16°18′58″N 122°04′01″E / 16.316°N 122.067°E[1] |
| Type | Thrust[3] |
| Areas affected | Philippines |
| Max. intensity | MMI IX (Violent)[1] PEIS VIII (Very destructive)[2] |
| Tsunami | .3 m (1 ft 0 in)[4] |
| Foreshocks | 10+[3] |
| Casualties | 207–271 dead, 261 injured[4] |
The 1968 Casiguran earthquake occurred on 04:19:22 local time on August 2 with a moment magnitude of 7.6 and a maximum Mercalli intensity of IX (Violent). The thrust earthquake's epicenter was in Casiguran, Quezon (now part of Aurora province). A small non-destructive tsunami was generated and at least 207 people were killed. The majority of the deaths occurred in the collapse of a six-story building in Manila.
Damage
In Manila, many structures that suffered severe damage had been built near the mouth of the Pasig River on huge alluvial deposits. A number of buildings were damaged beyond repair while others only suffered cosmetic damage. 268 people were reported to have died during the collapse of the six-story Ruby Tower, located at the corner of Doroteo Jose and Teodora Alonzo Streets in the district of Santa Cruz.[5][a] The entire building, save for a portion of the first and second floors at its northern end, was destroyed. Allegations of poor design and construction, as well as the use of poor-quality building materials arose.[7] In the district of Santa Ana, one person was injured by debris from a damaged apartment building. Two more people from Aurora sub province and Pampanga died as a direct result of the quake. Around the town of Casiguran, there were several reports of landslides, the most destructive one at Casiguran Bay.[8]
Aftershocks
The aftershock sequence throughout the month of August included many moderate shocks, including fifteen over 5.0 mb. The strongest of these occurred on August 3 with a 5.9 Ms event that produced intensities of III–IV in Manila.[9]
Aftermath and legacy
The former location of Ruby Tower in Santa Cruz district is now a memorial hall which stands today.[7][10]
See also
- 1990 Luzon earthquake
- 2022 Luzon earthquake
- List of earthquakes in 1968
- List of earthquakes in the Philippines
Notes
References
- ^ a b c d "M 7.6 – Luzon, Philippines". United States Geological Survey. August 1, 1968. Retrieved August 27, 2017.
- ^ a b "Destructive Earthquakes in the Philippines". Philippine Institute of Volcanology and Seismology. Retrieved October 17, 2021.
- ^ a b Su 1969, p. 459
- ^ a b PAGER-CAT Earthquake Catalog, Version 2008_06.1, United States Geological Survey, September 4, 2009
- ^ Moya, George P. (July 2, 2014). "When an earthquake hits Metro Manila". Rappler. Retrieved September 23, 2020.
- ^ Ynares, Dr. Jun. "The Ruby Tower". Manila Bulletin. Retrieved September 23, 2020.
- ^ a b Marianne V. Go (December 14, 2006). "Group warns vs substandard construction materials". The Philippine Star. Retrieved September 1, 2012.
- ^ "1968 August 02 Ms7.3 Casiguran Earthquake". Philippine Institute of Volcanology and Seismology. Retrieved June 18, 2024.
- ^ Su 1969, pp. 465–468
- ^ "Of Manila Earthquakes and Ruby Tower". The Urban Roamer. April 27, 2019. Retrieved September 23, 2020.
Sources
- Su, S. S. (1969), "The Luzon earthquake of 1 August 1968: A preliminary report", Bulletin of the Seismological Society of America, 59 (1): 459–472, Bibcode:1969BuSSA..59..459S, doi:10.1785/BSSA0590010459, archived from the original on September 23, 2015, retrieved November 9, 2013