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ML 4.2 Newhall Earthquake - 9/1/11
The 1st of September 2011, M4.2 Newhall Earthquake
(Egill Hauksson, Nancy King, Lucy Jones, Sinan Akciz, Karen Feltzer, Bob Dollar, Ken Hudnut, Kate Hutton, Anthony Guarino, Nick Scheckel) Version 1.0
Update - Thursday, September 1st, 2011 - 3:23PM
The M4.2 earthquake was located in the northeast corner of the 1994 M6.7 Northridge aftershock zone. Because the 1994 aftershocks have mostly died off, this event is not considered to be an aftershock of the M6.7 event. The last M>4 event in this general region occurred in May 2009, located about 20 miles to the southeast. The M4.2 is located about 10 miles NE of the Northridge event and about 8 miles SW of the San Fernando - Sylmar event. The fault movement was horizontal, on a northwest striking plane. So far, eight aftershocks have occurred with the largest of M3.0 at 2:35 pm. Magnitude M4 or greater events in the general area since 2000.
Magnitude M4 or greater events in the general area since 2000:
#YYY/MM/DD HH:mm:SS.ss ET MAG M LAT LON DEPTH Q EVID NPH NGRM
2001/01/14 02:26:14.06 le 4.26 l 34.284 -118.404 8.8 A 9173365 177 916 2001/01/14 02:50:53.69 le 4.05 l 34.289 -118.403 8.4 A 9173374 173 829 2001/09/09 23:59:18.04 le 4.24 l 34.059 -118.388 7.9 A 9703873 140 1531 2002/01/29 05:53:28.93 le 4.18 l 34.361 -118.657 14.2 A 9753485 129 1596 2007/08/09 07:58:49.59 le 4.66 l 34.300 -118.620 7.6 A 14312160 303 2005 2009/05/02 01:11:13.66 le 4.42 l 34.067 -118.882 14.2 A 10403777 179 2022 2011/09/01 20:47:07.75 le 4.25 l 34.343 -118.481 7.4 A 11001205 28 2199
| Estimated Modified Mercalli Intensity | I | II-III | IV | V | VI | VII | VIII | IX | X | |
|---|---|---|---|---|---|---|---|---|---|---|
| Est. Population Exposure | 11,839k* | 4,664k | 513k | 44k | 0 | 0 | 0 | 0 | 0 | |
| Perceived Shaking | Not Felt | Weak | Light | Moderate | Strong | Very Strong | Severe | Violent | Extreme | |
| Potential Structure Damage | Resistant | none | none | none | V. Light | Light | Moderate | Moderate/Heavy | Heavy | V. Heavy |
| Vulnerable | none | none | none | Light | Moderate | Moderate/Heavy | Heavy | V. Heavy | V. Heavy | |
Overall, the population in this region resides in structures that are highly resistant to earthquake shaking, though some vulnerable structures exist.
| Date (UTC) | Dist(km) | Mag | Max MMI(#) | Shaking Deaths |
|---|---|---|---|---|
| 1984-11-26 | 329 | 5.1 | V (17k) | 0 |
| 1994-01-17 | 23 | 6.7 | IX (181k) | 33 |
| 2003-12-22 | 275 | 6.6 | VII (213) | 2 |
Recent earthquakes in this area have caused secondary hazards such as landslides and liquefaction that might have contributed to losses.
| MMI | City | Population |
|---|---|---|
| IV | Santa Clarita | 169k |
| IV | San Fernando | 25k |
| II | North Glendale | 203k |
| II | Glendale | 195k |
| II | Hollywood | 168k |
| II | Palmdale | 135k |
| I | Los Angeles | 3,695k |
| I | Long Beach | 483k |
| I | Santa Ana | 343k |
| I | Anaheim | 328k |
| I | Riverside | 298k |
Moment Tensor Solution for M4.2 Newhall Earthquake
For additional information check, www.scsn.org, and http://earthquake.usgs.gov/