From USGS:
Magnitude 5.4 - SOUTHERN CALIFORNIA
2010 July 07 23:53:33 UTC
This event has been reviewed by a seismologist.
Magnitude 5.4
Date-Time Wednesday, July 07, 2010 at 23:53:33 UTC
Wednesday, July 07, 2010 at 04:53:33 PM at epicenter

Location 33.417°N, 116.483°W
Depth 11.7 km (7.3 miles)
Region SOUTHERN CALIFORNIA
Distances 22 km (13 miles) NNW (332°) from Borrego Springs, CA
23 km (14 miles) SE (131°) from Anza, CA
33 km (20 miles) NE (52°) from Lake Henshaw, CA
41 km (25 miles) SW (215°) from Indio, CA
45 km (28 miles) S (174°) from Palm Springs, CA
94 km (58 miles) NE (41°) from San Diego, CA

Location Uncertainty horizontal +/- 0.3 km (0.2 miles); depth +/- 0.6 km (0.4 miles)
Parameters Nph=122, Dmin=10 km, Rmss=0.26 sec, Gp= 29°,
M-type=local magnitude (ML), Version=3
Source California Integrated Seismic Net:
USGS Caltech CGS UCB UCSD UNR

Event ID ci10736069

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AFTERSHOCK PROBABILITY REPORT
Published on Wed Jul 7 16:56:14 2010 PDT
Southern California Seismic Network: a cooperative project of
U.S. Geological Survey, Pasadena, California
Caltech Seismological Laboratory, Pasadena, California

Version 1: This report supersedes any earlier probability reports about this event.

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MAINSHOCK
Magnitude : 5.9 Ml
Time : 7 Jul 2010 04:53:33 PM PDT
: 7 Jul 2010 23:53:33 UTC
Coordinates : 33 deg. 25.05 min. N, 116 deg. 28.96 min. W
13 mi. ( 21 km) NNW of Borrego Springs, CA
28 mi. ( 44 km) S of Palm Springs, CA
Event ID : 10736069

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STRONG AFTERSHOCKS (Magnitude 5 and larger) -
At this time (immediately after the mainshock) the probability of a strong and possibly damaging aftershock IN THE NEXT 7 DAYS is approximately 40 PERCENT.

EARTHQUAKES LARGER THAN THE MAINSHOCK -
Most likely, the recent mainshock will be the largest in the sequence. However, there is a small chance (APPROXIMATELY 5 TO 10 PERCENT) of an earthquake equal to or larger than this mainshock in the next 7 days.

WEAK AFTERSHOCKS (Magnitude 3 to 5) -
In addition, approximately 20 to 50 SMALL AFTERSHOCKS are expected in the same 7-DAY PERIOD and may be felt locally.

This probability report is based on the statistics of aftershocks typical for California. This is not an exact prediction, but only a rough guide to expected aftershock activity. This probability report may be revised as more information becomes available.

Background Information About Aftershocks
Like most earthquakes, the recent earthquake is expected to be followed by numerous aftershocks. Aftershocks are additional earthquakes that occur after the mainshock and in the same geographic area. Usually, aftershocks are smaller than the mainshock, but occasionally an aftershock may be strong enough to be felt widely throughout the area and may cause additional damage, particularly to structures already weakened in the mainshock. As a rule of thumb, aftershocks of magnitude 5 and larger are considered potentially damaging.

Aftershocks are most common immediately after the mainshock; their average number per day decreases rapidly as time passes. Aftershocks are most likely to be felt in the first few days after the mainshock, but may be felt weeks, months, or even years afterwards. In general, the larger the mainshock, the longer its aftershocks will be felt.

Aftershocks tend to occur near the mainshock, but the exact geographic pattern of the aftershocks varies from earthquake to earthquake and is not predictable. The larger the mainshock, the larger the area of aftershocks. While there is no "hard" cutoff distance beyond which an earthquake is totally incapable of triggering an aftershock, the vast majority of aftershocks are located close to the mainshock. As a rule of thumb, a magnitude 6 mainshock may have aftershocks up to 10 to 20 miles away, while a magnitude 7 mainshock may have aftershocks as far as 30 to 50 miles away.

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To: U.S. West Coast, Alaska, and British Columbia coastal regions
From: NOAA/NWS/West Coast and Alaska Tsunami Warning Center
Subject: Tsunami Information Statement issued 07/7/2010 at 4:57PM PDT

At 4:54 PM Pacific Daylight Time on July 7, an earthquake with preliminary magnitude 5.9 occurred 60 miles/97 Km northeast of San Diego, California .

The magnitude is such that a tsunami IS NOT EXPECTED. However, in coastal areas of intense shaking, locally generated tsunamis can be triggered by underwater landslides. This will be the only WCATWC message issued for this event.

The location and magnitude are based on preliminary information. Further information will be issued by the United States Geological Survey or the appropriate regional seismic network.