1968 Casiguran earthquake

1968 Casiguran earthquake
	Casiguran
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; 7.3 Ms
Depth	25 km (16 mi)
Epicenter	16°18′58″N 122°04′01″E / 16.316°N 122.067°E
Type	Thrust
Areas affected	Philippines
Max. intensity	MMI IX (Violent); ; PEIS VIII (Very destructive)
Tsunami	.3 m (1 ft 0 in)
Foreshocks	10+
Casualties	207–271 dead, 261 injured

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 M_s 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]

Notes

^ Some sources put the location of the site of Ruby Tower in Binondo, also in the same city.^[6]

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

External links

Casiguran Earthquake – 02 August 1968 – Philippine Institute of Volcanology and Seismology
M7.6 – Luzon, Philippines – United States Geological Survey
The International Seismological Centre has a bibliography and/or authoritative data for this event.

[7] Some sources put the location of the site of Ruby Tower in Binondo, also in the same city.^[6]

[USGS-1] "M 7.6 – Luzon, Philippines". United States Geological Survey. August 1, 1968. Retrieved August 27, 2017.

[PHIVOLCS-2] "Destructive Earthquakes in the Philippines". Philippine Institute of Volcanology and Seismology. Retrieved October 17, 2021.

[Su_459-3] Su 1969, p. 459

[PAGER-CAT-4] PAGER-CAT Earthquake Catalog, Version 2008_06.1, United States Geological Survey, September 4, 2009

[5] Moya, George P. (July 2, 2014). "When an earthquake hits Metro Manila". Rappler. Retrieved September 23, 2020.

[6] Ynares, Dr. Jun. "The Ruby Tower". Manila Bulletin. Retrieved September 23, 2020.

[Rappler-8] Marianne V. Go (December 14, 2006). "Group warns vs substandard construction materials". The Philippine Star. Retrieved September 1, 2012.

[9] "1968 August 02 Ms7.3 Casiguran Earthquake". Philippine Institute of Volcanology and Seismology. Retrieved June 18, 2024.

[10] Su 1969, pp. 465–468

[UR-11] "Of Manila Earthquakes and Ruby Tower". The Urban Roamer. April 27, 2019. Retrieved September 23, 2020.

[1]

[2]

[3]

[4]

[5]

[a]

[7]

[8]

[9]

[10]

[6]