Feeds & DataM 4.9 - 29.9 km (18.6 mi) W of Petrolia, CA
Friday, August 7, 2009 at 10:49:34 UTCLocation: 40.3°N 124.6°W Depth: 17km
Alert version 13
Summary
Estimated Population Exposed to Earthquake Shaking
| Est. Modified Mercalli Intensity | Est. Population Exposure (k = x1000) | Perceived Shaking | Potential Structure Damage | |
|---|---|---|---|---|
| Resistant | Vulnerable | |||
| X | 0 | Extreme | V. Heavy | V. Heavy |
| IX | 0 | Violent | Heavy | V. Heavy |
| VIII | 0 | Severe | Moderate/Heavy | Heavy |
| VII | 0 | Very Strong | Moderate | Moderate/Heavy |
| VI | 0 | Strong | Light | Moderate |
| V | 0 | Moderate | V. Light | Light |
| IV | 0 | Light | None | None |
| II-III | 38k | Weak | None | None |
| I | 94k* | Not Felt | None | None |
| MMI | City | Population |
|---|---|---|
| III | Rio Dell | 3k |
| II | Ferndale | 1k |
| II | Hydesville | 1k |
| II | Fortuna | 11k |
| II | Humboldt Hill | 3k |
| II | Bayview | 3k |
| II | Pine Hills | 3k |
| I | Myrtletown | 4k |
| I | Eureka | 25k |
| I | Arcata | 17k |
| I | McKinleyville | 15k |
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, the population in this region resides in structures that are resistant to earthquake shaking, though some vulnerable structures exist.
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/nc/shake/71261376.
Exposure
| Est. Modified Mercalli Intensity | Est. Population Exposure (k = x1000) | Perceived Shaking | Potential Structure Damage | |
|---|---|---|---|---|
| Resistant | Vulnerable | |||
| X | 0 | Extreme | V. Heavy | V. Heavy |
| IX | 0 | Violent | Heavy | V. Heavy |
| VIII | 0 | Severe | Moderate/Heavy | Heavy |
| VII | 0 | Very Strong | Moderate | Moderate/Heavy |
| VI | 0 | Strong | Light | Moderate |
| V | 0 | Moderate | V. Light | Light |
| IV | 0 | Light | None | None |
| II-III | 38k | Weak | None | None |
| I | 94k* | Not Felt | None | None |
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.
Cities
| MMI | City | Population |
|---|---|---|
| III | Rio Dell | 3k |
| II | Ferndale | 1k |
| II | Hydesville | 1k |
| II | Fortuna | 11k |
| II | Humboldt Hill | 3k |
| II | Bayview | 3k |
| II | Pine Hills | 3k |
| I | Myrtletown | 4k |
| I | Cutten | 3k |
| I | Eureka | 25k |
| I | Redway | 1k |
| I | Arcata | 17k |
| I | McKinleyville | 15k |
| I | Blue Lake | 1k |
| I | Laytonville | 1k |
| I | Willow Creek | 1k |
Table of MMI estimates and populations for settlements falling within the map boundaries. The settlement name, location, and population are obtained from the freely-available GeoNames geographical database.
