M 3.9 - 11.9 mi NW of Borrego Springs, CA

Summary

Population Exposure

 Population per ˜1 square km from Landscan 2005

Selected City Exposure

MMI	City	Population
I	Borrego Springs	2k
I	Tijuana	1376k
I	Chula Vista	213k
I	Ontario	172k
I	Moreno Valley	168k
I	Fontana	169k
I	San Bernardino	202k
I	Mexicali	597k
I	Riverside	297k
I	Rancho Cucamonga	168k
I	San Diego	1223k

Shaking Intensity

    MMI

Users should consider the preliminary nature of this information and check for updates as additional data becomes available. Population exposure estimates are NOT a direct estimate of earthquake damage; comparable shaking will result in significantly lower losses in regions with well built structures than in regions with vulnerable structures. Overall, structures in this region are designed to be resistant to earthquake shaking, though some vulnerable construction exists. A magnitude 6.7 earthquake struck the Northridge, California region on January 17, 1994 (UTC), with estimated population exposures of 110,000 at intensity IX or greater and 1.7 million at intensity VIII, resulting in 60 deaths. Recent earthquakes in this area have also triggered landslide and liquefaction hazards that have contributed to losses.

PAGER results are generally available on the Internet within 30 minutes of the earthquake's occurrence. However, information on the extent of shaking will be uncertain in the minutes and hours following an earthquake and typically improves as additional sensor data and reported intensities are acquired and incorporated into models of the earthquake's source. Users of PAGER exposure estimates should account for uncertainty and always seek the most current PAGER release for any earthquake.

Maps

Map of MMI contours plotted over population per ˜1 square km (see gray scale bar on top of map). The regions of integer MMI values are separated by the thick contour lines and labeled with Roman numerals. The total population exposure to a given MMI value is obtained by summing the population between the thick contour lines. This total is shown in population exposure table.

Map of shaking intensity. This map shows the estimated MMI as a continuous color scale. The ground shaking estimates can be obtained from http://earthquake.usgs.gov/shakemap/ci/shake/14352016.

Exposure

Table showing population exposed to different estimated Modified Mercalli Intensity (MMI) levels and the possible damage at different intensity levels for resistant and vulnerable structures. MMI describes the severity of an earthquake in terms of its effect on humans and structures and is a rough measure of the amount of shaking at a given location. Unlike earthquake magnitude, intensity varies with distance from the fault, and is influenced by the depth of the earthquake and the types of soils in the shaken region. Population outside the map bounds are not included in the totals.

Downloads

• 
  onePAGER PDF
  298 kB
• 
  Exposure XML
  53 kB
• 
  Shakemap
  24 kB
• 
  Population Map
  51 kB
• 
  Population PDF
  177 kB

Details