1968 Casiguran earthquake
.svg.png)  Manila  | |
| Date | August 1, 1968 |
|---|---|
| Origin time | 20:19:22 UTC [1] |
| Magnitude | 7.6 Mw [1] |
| Depth | 25 km (16 mi) [1] |
| Epicenter | 16°19′N 122°04′E / 16.32°N 122.07°ECoordinates: 16°19′N 122°04′E / 16.32°N 122.07°E [1] |
| Type | Thrust [2] |
| Areas affected | Philippines |
| Max. intensity | IX (Violent) [3] |
| Tsunami | .3 m (1 ft 0 in) [3] |
| Foreshocks | 10+ [2] |
| Casualties | 207–271 dead, 261 injured [3] |
The 1968 Casiguran earthquake occurred on August 1 at 20:19 UTC 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. Several hundred people died during the collapse of the six-story Ruby Tower, located in the district of Binondo. 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 use of low-quality building materials, arose.[4] 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.
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.[5]
References
- 1 2 3 4 ISC (2015), ISC-GEM Global Instrumental Earthquake Catalogue (1900–2009), Version 2.0, International Seismological Centre
- 1 2 Su 1969, p. 459
- 1 2 3 USGS (September 4, 2009), PAGER-CAT Earthquake Catalog, Version 2008_06.1, United States Geological Survey
- ↑ Marianne V. Go (December 14, 2006). "Group warns vs substandard construction materials". The Philippine Star. Retrieved September 1, 2012.
- ↑ Su 1969, pp. 465–468
Sources
- Su, S. S. (1969), "The Luzon earthquake of 1 August 1968: A preliminary report", Bulletin of the Seismological Society of America, Seismological Society of America, 59 (1): 459–472
External links
- Casiguran Earthquake - 02 August 1968 – Philippine Institute of Volcanology and Seismology
- M7.6 - Luzon, Philippines – United States Geological Survey