 |
| Malindig Volcano is located at the southern tip of island Marinduque. Screengrab from Google Earth. Are these earthquakes purely tectonic in origin or could they be related to magma incursions as a movement of a so-called 'Boac River Fault' also took place in recent months?
Renato Solidum, director of the Philippine Institute of Volcanology and Seismology, said the quakes that struck Marinduque were called “earthquake swarms.”
|
“These are part of an earthquake swarm occurring at the eastern end of Lubang fault,” Solidum told The STAR today Oct. 14.
Solidum said earthquake swarms are common. “In most cases, many of the quakes are non-destructive,” he said.
"But we don’t discount the possibility of stronger ones that can be larger,” he added. Read Philstar
Earthquakes and volcanoes related?
Earthquakes and volcanoes related?
It's not always the case but earthquakes do foretell volcanic activity sometimes. There are instances when earth near a volcano starts to rumble serving as warning for an impending eruption.
In a news report about the eruption of a volcano in Iceland, a volcanologist at the University of Houston, Jonathan Snow, said, "It's very common for the two to be linked.. volcanic eruptions are usually preceded by earthquakes large and small." Snow describes it as a "symbiotic" relationship.
The close geological connection is rooted in the shifting of Earth's tectonic plates against each other that can also jostle magma beneath volcanoes, urging it upward.
Most earthquakes are along the edges of tectonic plates where most volcanoes are also located.
Phivolcs lists Mt. Malindig, 13.240 N, 122.018 E, with summit elevation of 1157 m (3,796 ft), as a potentially active stratovolcano. The recent earthquakes are within the 30 km radius of Malindig.
Illustration below shows the Central Marinduque and Lubang Faults.
 |
| Source: Phivolcs |
 |
| Another map showing Central Marinduque Fault and Lubang Fault
At least 14 earthquakes jolted the province of Marinduque that started Saturday afternoon until Sunday morning, according to the Philippine Institute of Volcanology and Seismology (Philvocs). In a phone interview, Ishmael Narag, officer in charge of seismologist of earthquake monitoring division of the agency, said the quakes which happened in Marinduque were called “earthquake swarms” which “are events where a local area experiences sequences of many earthquakes striking in a relatively short period of time.”
“Swarm of events happened in Marinduque, we don’t expect aftershocks but the events followed one (temblor) after the other in time and in same location,” Narag explained. Phivolcs said the first tremor struck Boac, Marinduque atg 6:33 p.m. Saturday with a magnitude of 4.5 occurred. The epicenter was traced 29 kilometers northwest of Boac town. The quake had a depth of 32 kms. The agency said Intensity 3 quake occurred in Batangas City; Boac, Marinduque while, Intensity 1 at Tagaytay City. At around 9:06 p.m., the second tremor, with a magnitude of 3.0, took place. Its epicenter was located 26 kilometers southwest of Boac with a depth of one kilometer. At around 10:54 p.m., the third tremor, with a magnitude of 2.5, took place. Its epicenter was located 34 kilometers northwest of Boac with a depth of seven kms. At around 12:55 a.m. Sunday, the fourth tremor, with magnitude of 3.6, took place. Its epicenter was located 36 kilometers northwest of Boac with a depth of 15 kilometers. At around 1:08 a.m., the fifth tremor took place with magnitude 2.6, took place. The epicenter was located 30 kilometers northwest of Boac with a depth of 15 kilometers. At around 1:44 a.m., the sixth tremor took place with magnitude 1.4, took place. The epicenters of the eight succeeding quakes were all located in northwest of Boac and ranged from 1.8 to 4.2 magnitude. The 14th and last tremor was recorded around 7:20 a.m. on Sunday, with magnitude 2.8. Its epicenter was located 24 kilometers northwest of Boac with a depth of 21 kilometers. Narag said there were no damage or casualty reported from the 14 temblors, which were all tectonic in origin. |
