6242 Philippines’ Earthquakes in 2018 – an Analysis

6442 Philippines’ Earthquakes counted in the Year 2018.

These are about 1500 more quakes than in 2017. Is the underground of the Philippines getting more nervous? Has it become more dangerous to live in the Philippines?

Let’s have a look on the comparison table from 2011 to 2018:

Comparing the total numbers of Philippines’ Earthquakes (rightmost column) one could think that earth is much more often shaking now than 8 years ago. But looking at the Medium and Strong columns you discover that with exception of 2012, all the years the earthquake activity had been similar. In 2012 the Philippine Trench had been very active. But also in 2018 3 out of the 5 strong earthquakes happened in the southern part of the
Philippine Trench.

The increase of the number of weak earthquakes looks rather dramatically :

The origin of the increase is rather simple. We receive the raw data from Phivolcs,  the Philippine Institute of Volcanology and Seismology. In the last four years Phivolcs had heavily invested in new observatories and new monitoring stations. Phivolcs had started out with only 12 seismic stations in 1984. Last Occober 4,2018, they established their 100^th monitoring station.

With this much denser monitoring network, Phivolcs can detect and localise much more weak Philippines’ Earthquakes. The increase of the number of monitoring stations has also an impact on data quality.
In the beginning the volcanologist could just say: This morning there had again been a rather strong earthquake in the vicinity of western Negros.
Today the messages are much more precise like:
Today at 9:31 AM a Magnitude 4.8 earthquake shook the region of Sipalay. The focus of the quake laid 84 km deep at 44° North and 28 km West of Sipalay town.

Why we create our own statistics?

The origin of our own statistics had been the question: Where is it most safe to settle in the Philippines regarding the risk of a strong earthquake?
Phivolcs had never published overview maps of the earthquake density and intensity like the one below:

Another question that often raises is: Where in the Philippines happen the strongest earthquakes? There are islands that are often struck by medium and strong quakes like southern Mindanao. On the other side one finds rather quiet places like Palawan or Panay.

Why did we change the map style?

When you go back to earlier years 2011 to 2017, you see a change of map style and a text overlay by Google. In 2018 Google changed its map usage policy and increased the price per map-di by a factor of 14!
With more than 600,000 visitors per year we couldn’t afford anymore to use Google Maps.
We therefore switched to Open Layers, Open Streetmap and Mapbox.
We’ll explain the Google problem in one of our next articles.

[GARD]