‘Di Lang Magnitude: PHIVOLCS Explains Why Earthquake Hit Harder in Cebu Than in Davao

 October 12, 2025

Introduction

Sa tuwing may malakas na lindol, agad na tumitingin ang publiko sa magnitude bilang sukatan ng lakas. Ngunit ayon sa PHIVOLCS (Philippine Institute of Volcanology and Seismology), hindi lang magnitude ang dahilan kung bakit mas grabe ang epekto ng lindol sa Cebu nitong linggo — kahit na mas malapit ang epicenter sa Davao.

Maraming netizen ang nagtaka:

“Bakit mas malayo ang Davao pero mas konti ang pinsala? Samantalang sa Cebu, grabe ang yayanig?”

Ang sagot? Masalimuot, pero makatuwiran.

Table of Contents

Magnitude vs. Intensity: Ano ang Kaibahan?
Bakit Mas Malakas ang Yayanig sa Cebu?
Istruktura at Lupa: Cebu’s Built Environment Factor
Depth of the Quake: Mababa, Mas Malupit
Type of Soil: Amplification Effects
Distance from the Fault Line Isn’t Everything
Vertical vs. Horizontal Shaking
Urban Density: More Structures, More Damage
Preparedness Level: Davao vs. Cebu
What This Means for Future Earthquake Response

1. Magnitude vs. Intensity: Ano ang Kaibahan?

Magnitude is the measure of energy released at the source of the earthquake — ito ang number na karaniwang binabanggit sa balita (e.g., Magnitude 6.8).
Intensity, on the other hand, refers to how the quake is felt on the ground, which varies per location.

PHIVOLCS:
“A single magnitude can have many different intensities depending on location, soil, and infrastructure.”

2. Bakit Mas Malakas ang Yayanig sa Cebu?

PHIVOLCS explained that although the epicenter was nearer Davao, Cebu experienced higher ground shaking intensity, specifically Intensity VII (destructive), compared to Intensity V to VI (strong to moderately strong) in Davao.

3. Istruktura at Lupa: Cebu’s Built Environment Factor

Cebu City is built on a mixture of reclaimed land, limestone, and alluvial deposits, which are prone to amplify shaking during seismic events. Davao, in contrast, has more stable bedrock in many urban areas.

“Mas lumalakas ang pagyanig sa mga lugar na malambot ang lupa,” ayon sa PHIVOLCS.

4. Depth of the Quake: Mababa, Mas Malupit

The earthquake’s hypocenter (depth) was shallow — estimated at 12 km below surface. Shallow earthquakes tend to cause more intense surface shaking, particularly in areas directly affected by wave amplification.

5. Type of Soil: Amplification Effects

PHIVOLCS categorized Cebu’s central district as having “soft to medium soil”, which acts like a resonator — absorbing seismic energy and releasing it with greater force on the surface.

In comparison, Davao’s deeper foundation and harder ground dampens seismic energy, resulting in less intense ground movement.

6. Distance from the Fault Line Isn’t Everything

While Davao was closer to the epicenter, it was located on the less active edge of the seismic rupture. Cebu, despite being farther, aligned with the direction of energy propagation, increasing the felt intensity.

“Think of it like ripples from a stone — the direction matters as much as the distance,” PHIVOLCS added.

7. Vertical vs. Horizontal Shaking

Cebu reportedly experienced more vertical ground movement, which is more destructive to buildings and infrastructure. Horizontal shaking may feel strong but typically causes less structural damage, depending on design.

8. Urban Density: More Structures, More Damage

Cebu is more densely built than most parts of Davao, with high-rise buildings, overpasses, malls, and commercial centers packed in tight spaces. This amplifies secondary hazards like falling debris, shattered glass, and damaged roads.

9. Preparedness Level: Davao vs. Cebu

Davao has long been a model for disaster preparedness, with frequent earthquake drills, stricter zoning, and modern infrastructure codes. Cebu, while active in disaster risk reduction, reportedly has more aging buildings and fewer “earthquake-ready” designs in older zones.

10. What This Means for Future Earthquake Response

The event underscores an important lesson: Earthquake impact isn’t just about how strong it is — but where, how, and what it hits.

PHIVOLCS and LGUs now call for:

Reassessment of soil and structural risks in Cebu and other urban areas
Retrofitting of vulnerable buildings
Stricter compliance with building codes
Public awareness on intensity vs. magnitude

Conclusion

The recent earthquake served as a wake-up call for Central Visayas — reminding us that seismic risk is complex, and that preparedness must go beyond location. While magnitude may capture headlines, it’s intensity, soil composition, and infrastructure resilience that determine the real-life impact.

As PHIVOLCS puts it:

“Don’t just look at the number. Look at the ground you’re standing on.”

Related Articles

“Understanding the Earthquake Intensity Scale: A Quick Guide”
“Reclaimed Land and Earthquake Risk: Why Location Matters”
“Top 10 Earthquake-Resilient Cities in the Philippines”
“PHIVOLCS Earthquake Preparedness Tips for Urban Areas”
“Why Some Cities Shake Harder: Lessons from Past Quakes”

Note: This article is based on official reports from PHIVOLCS and verified seismological data as of October 12, 2025.