1867 Keelung earthquake
Local date | December 18, 1867 |
---|---|
Local time | morning |
Magnitude | 6.8 ML 7.0–7.24 Mw |
Depth | 10 km (6.2 mi) |
Epicenter | 25°20′N 121°55′E / 25.34°N 121.91°E |
Areas affected | Taiwan |
Max. intensity | CWA 7 |
Tsunami | 15 m (49 ft) |
Casualties | 580 dead; 100+ injured[1] |
The 1867 Keelung earthquake occurred off the northern coast of Taiwan on the morning of December 18 with a magnitude of 7.0. It produced strong shaking that seriously damaged the cities of Keelung and Taipei. A tsunami, thought to be the only confirmed destructive of its kind in Taiwan, drowned hundreds and had a run-up exceeding 15 m (49 ft). The total death toll was estimated to be 580 while more than 100 were injured. It was followed by aftershocks that were felt on average ten times a day.[2]
Tectonic setting
Taiwan is situated on a complex convergent boundary between the Eurasian Plate and the Philippine Sea Plate.[3] Off the northeastern coast of the island, the Philippine Sea Plate subducts northwards beneath the Ryukyu Islands (on the overriding Eurasian Plate) along the Ryukyu Trench. To the south of the island, oceanic crust of the Eurasian Plate subducts beneath eastwards the Philippine Sea Plate along the Manila Trench. Taiwan lies at the junction of the two subduction zones, on the edge of the Asian continental margin (Eurasian Plate), where the northwest–southeast convergence rate is estimated to be 7 cm/year. Continental collision occurs due to convergence of the Asian continental crust with continental crust of the Philippine Sea Plate on the island. Continental crust of the Eurasian Plate is being subducted beneath the island, forming east-dipping thrust faults.[4]
Geology
Multiple studies have been conducted to identify the source of the earthquake and subsequent tsunami. The
The lack of historical documentation of the tsunami effects made identifying the fault difficult. Academics have associated the earthquake with a rupture along the Shanchiao Fault, a northeast–southwest trending
In a 2017 study by Sugawara and others, modelling of the earthquake suggest a 7.24 Mw event with coseismic slip of 6 meters was required to reproduce the tsunami heights reported. The modelled earthquake involved a rupture on the onshore and offshore segments.[2] An earlier study (2016) by Cheng and others estimated a 40 km (25 mi) rupture offshore at a depth of 10 km (6.2 mi) was consistent with the seismic intensity and tsunami reports. The modelled earthquake had a Mw of 7.0 and an epicenter located at 25°20′N 121°55′E / 25.34°N 121.91°E.[5]
Earthquake
The earthquake occurred at 09:00 or 10:00
Tsunami
Seawater receded approximately five minutes after the earthquake and 25 minutes later, exposed the seafloor by 500 m (1,600 ft). The tsunami struck at 11:00 local time, killed between 70 and 80 people in Jinshan. Tsunami victims were also reported at
Volcanic eruption
A report of a submarine eruption at the time of the earthquake and tsunami was vaguely described and published in 1917.[9] It is thought to be the only instance of an earthquake, tsunami and eruption occurring at the same time in the region.[1] The eruption occurred off the northeast coast of the island but nature of it is unknown.[9]
See also
References
- ^ doi:10.7289/V5PN93H7, retrieved 10 June 2022
- ^ S2CID 197554538.
- S2CID 18681733.
- ^ J.G. Liou; L.Y. Hsiao (1 October 1999). "Report #4 on the Chi-Chi (Taiwan) Earthquake: Tectonic Setting and Regional Geology of Taiwan". United States Geological Survey. Archived from the original on 4 February 2020. Retrieved 10 June 2022.
- ^ .
- doi:10.7289/V5TD9V7K. Retrieved 10 June 2022.
- S2CID 224901625.
- .
- ^ a b "Unnamed". Global Volcanism Program. Smithsonian Institution. Archived from the original on 13 July 2007. Retrieved 10 June 2022.