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2025 Hazard Mitigation Plan <br />Kittitas County, Washington <br /> <br /> <br />Chapter 4: Hazard Identification and Risk Assessment 109 <br />Figure 4-11 illustrates earthquake events greater than Magnitude 4.1 within 20 miles of Kittitas County. <br />Figure 4-11. Earthquake History in Kittitas County Area <br /> <br />4.6.4.3. Hazard Extent/Intensity <br />Earthquakes are measured both in terms of their inherent magnitude and in terms of their local intensity. <br />There are several standard measures of earthquakes, including the Richter Scale and the Modified <br />Mercalli Intensity (MMI) scale. The Richter Scale measures the magnitude or amount of energy an <br />earthquake releases. Magnitude is measured by seismographs. The MMI scale is an observed <br />measurement of the earthquake’s intensity felt at the earth’s surface and it varies depending on the <br />observer’s location at the earthquake’s epicenter. The MMI Scale is comprised of 12 increasing levels, <br />designated by Roman numerals, which range from imperceptible shaking to catastrophic destruction. <br />Furthermore, the MMI can be used to map earthquake impacts.133F <br />133 <br /> <br />Table 4-50 correlates the MMI Scale with the Richter Scale and effects of ground shaking. <br /> <br /> <br />133 Pacific Northwest Seismic Network. (n.d.). Magnitude/Intensity. Retrieved from <br />https://pnsn.org/outreach/about-earthquakes/magnitude-intensity.