Two strong and shallow earthquakes with magnitudes 6.2 and 6.9 struck Gulf of California

Two strong and shallow earthquakes with magnitudes 6.2 and 6.9 struck Gulf of California

Two strong and shallow earthquakes struck Gulf of California on April 12, 2012. First earthquake was measured with magnitude 6.2 at 07:06:01 UTC with depth of 10.1km. A second earthquake struck same area less than 10 minutes later, at 07:15:49 UTC, recorded magnitude was 6.9 with depth at 10.3km.

NO tsunami warning, watch or advisory is in effect for these areas.

The set of earthquakes in the Gulf of California have started with a M4.7 earthquake, followed 18 minutes later by a M6.2 earthquake and another 9 minutes later with a M6.9 earthquake (the most powerful so far)

USGS has calculated that 3000 people will have experienced a very strong shaking and that 105,000 have experienced a strong shaking. Both these areas are at risk for eventual damage, especially because 9 minutes earlier another very strong earthquake struck the same area.

The Mexican Servico Sismologico Nacional reports a magnitude of 6.8 with an epicenter below land. USGS hypocenter is at M6.9 and off the coast.

Epicentral area  is very sparsely populated with only a few houses along the coastline apart from Santa Isabel.

Although it is a ridge earthquake, the epicenter of the M6.9 quake looks to be very close to the coast which makes this earthquake (the second very strong in a matter of 9 minutes) EXTREMELY DANGEROUS for shaking damage and fatalities. Let us hope that we are too pessimistic here. The kind of shaking will depend on the focal mechanism.

Following calculations by the USGS (providing that the earthquake data are correct) a MMI VII will have been experienced on the Baja California peninsula ! This means dangerous for the coastal areas experiencing this kind of shaking.

Updates will be posted accordingly. 

Magnitude6.2
Date-Time
  • Thursday, April 12, 2012 at 07:06:01 UTC
  • Thursday, April 12, 2012 at 12:06:01 AM at epicenter
Location28.841°N, 113.072°W
Depth10.1 km (6.3 miles)
RegionGULF OF CALIFORNIA
Distances142 km (88 miles) NE of Guerrero Negro, Baja Calif. Sur, Mexico
182 km (113 miles) NNW of Santa Rosalia, Baja Calif. Sur, Mexico
207 km (128 miles) W of Hermosillo, Sonora, Mexico
519 km (322 miles) S of PHOENIX, Arizona
Location Uncertaintyhorizontal +/- 17.3 km (10.7 miles); depth +/- 2.7 km (1.7 miles)
ParametersNST=372, Nph=372, Dmin=187 km, Rmss=1.56 sec, Gp=104°,
M-type=regional moment magnitude (Mw), Version=8
Source
  • Magnitude: USGS NEIC (WDCS-D)
    Location: USGS NEIC (WDCS-D)
Event IDusc000919m
 



Magnitude6.9
Date-Time
  • Thursday, April 12, 2012 at 07:15:48 UTC
  • Thursday, April 12, 2012 at 12:15:48 AM at epicenter
Location28.790°N, 113.142°W
Depth10.3 km (6.4 miles)
RegionGULF OF CALIFORNIA
Distances133 km (82 miles) NE of Guerrero Negro, Baja Calif. Sur, Mexico
179 km (111 miles) NNW of Santa Rosalia, Baja Calif. Sur, Mexico
215 km (133 miles) W of Hermosillo, Sonora, Mexico
526 km (326 miles) SSW of PHOENIX, Arizona
Location Uncertaintyhorizontal +/- 18.1 km (11.2 miles); depth +/- 4.1 km (2.5 miles)
ParametersNST=331, Nph=331, Dmin=216 km, Rmss=1.32 sec, Gp=162°,
M-type=regional moment magnitude (Mw), Version=D
Source
  • Magnitude: USGS NEIC (WDCS-D)
    Location: USGS NEIC (WDCS-D)
Event IDusc00091a1




Indepth info and reports here.

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