Philippines earthquakes

M7.0 earthquake 18 km E of Aras-asan, Philippines

A magnitude 7.0 earthquake struck 18 km E of Aras-asan, Philippines on Mon, Feb 18, 1991, 10:37 AM GMT+8 (02:37 UTC), 24 km (15 mi) below the surface.

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Map

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The earthquake

Magnitude: 7.0 (Mw, moment), major
Magnitude from: USGS National Earthquake Information Center
Local time: Mon, Feb 18, 1991, 10:37 AM GMT+8
UTC: 1991-02-18 02:37:25 UTC
Depth: 23.9 km (14.9 mi), shallow
Epicenter: 8.870° N, 126.480° E
Region: Philippines
Strongest shaking: VII, very strong shaking
Tsunami flag: No
Status: Reviewed by a seismologist

Magnitude estimates

Different scales measure different things and differ by a few tenths. The USGS marks one as preferred, and it is the one this page uses.

Mag.	Scale	Computed by	Notes
7.0	Mw, moment	USGS National Earthquake Information Center	Preferred · Reviewed
6.74	Mw, moment	ISC-GEM global catalog	Final · ±0.1
6.7	Mwc, centroid moment	Global CMT project	Preliminary
6.7	Mww, W-phase moment	Duputel, W-phase inversion	Preliminary

What happened

The USGS’s account of the effects of this earthquake.

Felt (III RF) at Cagayan de Oro, Bislig and on Mactan and (I RF) at Cotabato. Depth from broadband displacement seismograms. FAULT PLANE SOLUTION: P-Waves NP1:Strike=355 Dip=68 Slip=105 NP2:Strike=139 Dip=26 Slip=57 Principal Axes: (T) Plg=64 Azm=290 (P) Plg=22 Azm=74 Comment: The focal mechanism is poorly controlled and corresponds to reverse faulting with a small left-lateral strike-slip component. The preferred fault plane is NP2. RADIATED ENERGY No. of sta: 4 Focal mech. F Energy 5.0+1.5*10**13 Nm MOMENT TENSOR SOLUTION Dep 25 No. of sta: 14 Moment Tensor; Scale 10**19 Nm Mrr=1.86 Mtt=0.20 Mff=-2.06 Mrt=-1.16 Mrf=2.98 Mtf=0.11 Principal axes: (T) Val=3.73 Plg=59 Azm=238 (N) Val=0.04 Plg=9 Azm=344 (P) Val=-3.77 Plg=29 Azm=79 Best Double Couple:Mo=3.8*10**19 NP1:Strike=194 Dip=18 Slip=121 NP2:Strike=341 Dip=75 Slip=81 CENTROID, MOMENT TENSOR (HRV) Data Used: GDSN L.P.B.: 14S, 38C M.W.: 18S, 34C Centroid Location: Origin Time 02:37:35.1 0.1 Lat 9.15N 0.01 Lon 126.79E 0.01 Dep 27.7 0.6 Half-duration 8.0 Moment Tensor; Scale 10**19 Nm Mrr=1.12 0.01 Mtt=-0.01 0.01 Mff=-1.11 0.01 Mrt=0.18 0.03 Mrf=1.10 0.04 Mtf=-0.15 0.01 Principal Axes: (T) Val=1.58 Plg=68 Azm=280 (N) Val=0.01 Plg=1 Azm=188 (P) Val=-1.59 Plg=22 Azm=98 Best Double Couple:Mo=1.6*10**19 NP1:Strike=186 Dip=23 Slip=88 NP2:Strike=9 Dip=67 Slip=91

From the USGS event page for usp0004n2a. U.S. Geological Survey text and figures are in the public domain.

Shaking

The USGS ShakeMap: shaking estimated from seismic stations and the quake’s size, on the Modified Mercalli intensity scale.

Strongest estimated: VII, very strong shaking
Peak ground acceleration: 23.6% of gravity
Peak ground velocity: 3.2 cm/s
Map: Automatic

USGS ShakeMap: estimated shaking intensity around the epicenter — Estimated shaking intensity. Map: USGS ShakeMap.

Did you feel it?

No one has reported feeling this quake to the USGS.

Fault motion and ground failure

How the rock slipped, from the moment tensor, and the USGS estimate of landslides and liquefaction.

Faulting: Reverse (thrust)
Moment magnitude: 6.7 Mww
Nodal plane 1: Strike 8°, dip 60°, rake 104°
Nodal plane 2: Strike 161°, dip 32°, rake 66°

How well it is located

Reviewed by a seismologist.

Depth from: OPERATOR_ASSIGNED

Nearest places

Distance and direction from each place to the epicenter, with its forecast.

Nearby

Within 100 km, magnitude 4.0 and up: 25 in the 60 days after this one and 0 in the 30 days before it.

After

Earthquakes today Philippines earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event usp0004n2a (also filed as gcmtc021891a, gcmt19910218023728, duputel021891a, atlas19910218023728, iscgem341899). Read Thu, Oct 1, 2026, 4:16 PM UTC.