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A small shallow-seated earthquake with magnitude of M4.3 and depth of 4 kilometers occurred at 10:08 PM 14 October 2021PST. The location of the epicenter was determined to be at 13.65 North Latitude and 123.14 East Longitude or at 3km N75W of Canaman, Camarines Sur. After this initial event, a sequence of small earthquakes followed and were recorded and subsequently located in this general location. A table below summarizes the located earthquake events that are posted at the Official website of DOST-PHIVOLCS (http://www.phivolcs.dost.gov.ph)

A total of 27 earthquakes were recorded by the nearest DOST-PHIVOLCS earthquake monitoring station located in San Jose, Camarines Sur (Station Code: SCSP). Magnitude ranges from 1.7 to 4.3 with crustal shallow depths between 1 km to 40 km.  The last recorded event associated with this earthquake sequence was at 1:22 AM 18 October 2021. There was no similar event that followed as of 6:00 AM 18 October 2021.

Ten events were felt at various intensities in the Camarines Norte, Camarines Sur and Albay. Calculation of the intensity distribution for the first event was performed using the Rapid Earthquake Damage Assessment System (REDAS) software using the latest calculated parameters of the earthquake. Results show that the magnitude and shallow-depth of this inland event has a potential to cause damages in the general vicinity of the epicenter. The Office of Civil Defense (OCD) was immediately informed about this during the information release of the first event. Social media posts indicate that the event was widely felt with unconfirmed observations of non-structural damages (glass door was damaged) and damages to building content. This prompted OCD to instruct their regional office to investigate damages in the area.

From the data presented above, this sequence of events, showing no identifiable large event, can be considered as an earthquake swarm that may occur in a tectonically active region, as suggested by sparse seismicity in this area of the Bicol region. A similar short-duration burst of earthquake activity occurred back in 13 December 1993 that did not culminate to a major event. Back then, areas do not have wider built-up areas and are sparsely populated to cause observable effects to warrant public attention.

DOST-PHIVOLCS will closely monitor any progress of this earthquake activity and will continue to post updated information at the PHIVOLCS Official website.

 

 

DOST-PHIVOLCS


 

 

Date & Time

Latitude

Longitude

Depth

(in km)

Magnitude

Location

Maximum Reported Intensity

14 Oct 2021 - 10:08 PM

13.65 N

123.14 E

1

4.3

3 km N75W of Canaman, Camarines Sur

Intensity V

15 Oct 2021 - 1:20 AM

13.65 N

123.11 E

4

4.2

1 km S85E of Canaman, Camarines Sur

Intensity IV

15 Oct 2021 - 1:28 AM

13.58 N

123.11 E

1

3.8

10 km S41W of Canaman, Camarines Sur

Intensity IV

15 Oct 2021 - 1:41 AM

13.59 N

123.16 E

9

2.1

7 km S6W of Canaman, Camarines Sur

No reported intensity

15 Oct 2021 - 2:03 AM

13.77 N

123.31 E

23

2.6

20 km N50E of Canaman, Camarines Sur

Intensity II

15 Oct 2021 - 2:14 AM

13.71 N

123.13 E

20

2.5

8 km N29W of Canaman, Camarines Sur

Intensity II

15 Oct 2021 - 2:22 AM

13.65 N

123.15 E

1

3.5

2 km W of Canaman, Camarines Sur

Intensity III

15 Oct 2021 - 2:33 AM

13.74 N

123.34 E

34

2.0

21 km N59W of Canaman, Camarines Sur

No reported intensity

15 Oct 2021 - 2:54 AM

13.69 N

123.16 E

1

2.1

5 km N20W of Canaman, Camarines Sur

No reported intensity

15 Oct 2021 - 3:22 AM

13.68 N

123.15 E

15

2.4

5 km N32W of Canaman, Camarines Sur

No reported intensity

15 Oct 2021 - 4:30 AM

13.67 N

123.13 E

1

2.5

5 km N63W of Canaman, Camarines Sur

No reported intensity

15 Oct 2021 - 11:27 PM

13.86 N

123.20 E

7

2.5

24 km N06E of Canaman, Camarines Sur

No reported intensity

16 Oct 2021 - 6:53 AM

13.62 N

123.12 E

1

3.3

6 km S63W of Canaman, Camarines Sur

Intensity III

17 Oct 2021 - 04:18 PM

13.73

123.16

1

3.4

9 km N09W of Canaman, Camarines Sur

Intensity IV

17 Oct 2021 - 05:06 PM

13.64

123.15

1

3.2

2 km S76W of Canaman, Camarines Sur

Intensity IV

17 Oct 2021 - 06:51 PM

13.67

123.16

5

4.2

3 km N31E of Canaman, Camarines Sur

Intensity V

18 Oct 2021 - 01:21 AM

13.68 N

123.31 E

40

1.7

15 km N78E of Canaman, Camarines Sur

No reported intensity

Table 1.0:  Preliminary parameters of located earthquakes associated with the 14-18 October 2021 Earthquake Sequence. These values may be updated as new data are received and processed.

 

 

 

CamSur 2021 October Earthquake Sequence

Figure 1.0: Map showing preliminary location of epicenters associated with the 14-18 October Earthquake Sequence